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Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 Shemesh, M. 6
Induction of Uterine Cyclooxygenase by Leutenizing Hormone and
Estradiol is an Important Determinant of Bovine Luteolysis
Shemesh, M.,
1
Shore, L.S.,
1
Fields, M.J.
2
and Hansel, W.
3
1
Kimron Veterinary Institute, Bet Dagan, Israel 50250.
2
University of Florida, Gainesville, FL 32611, United States of America.
3
Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA, 70808,
United States of America.
*
Corresponding Author: Prof. Mordechai Shemesh, Kimron Veterinary Institute, Bet Dagan, Israel 50250. E-mail: mordechai.shemesh@mail.huji.ac.il
ABSTRACT
Termination of the functional bovine corpus luteum is associated with a precipitous fall in peripheral plasma
progesterone which is induced by a pulsatile release of prostaglandin F
2α (PGF) from the late luteal phase
uterus. Te production of uterine PGF from arachidonic acid is greatest in endometrial cells 2-5 and 15– 17
days post-ovulation. Similarly exposure of uterine endometrial cells to estradiol 17β or to lutenizing hormone
(LH) results in a signifcant increase in LH receptors, cyclooxygenase-2 (COX-2) and PGF at 2-5 and 15-
17 days post-ovulation. It is therefore suggested that hormonal regulation of uterine COX- 2 by pulses of
estradiol and LH may play a role in bovine luteolysis.
Keywords: Lutelysis; COX-2; Lutenizing Hormone; Prostaglandin F2α
REVIEW
Events associated with regression of the bovine
corpus luteum (CL)
Tis review presents an overview of research carried out in
our laboratory over some forty years associated with the
subject of the regression of the bovine CL.
Peripheral plasma of progesterone
Peripheral plasma concentrations of progesterone are a valu-
able indication of the concentration of hormone reaching
target organs and control centers governing secretion of
gonadotropins at various phases of the reproductive cycle.
Alterations in circulating progesterone also supplies informa-
tion regarding the functional state of the corpus luteum (CL)
or of alternative sources of the hormone such as the adrenal
or placenta (1-3).
In our early work (4-6), we demonstrated that in the
absence of an early embryo in the uterus, there is a precipitous
fall in luteal progesterone secretion toward day 18-19 of the
cycle. Tis divergence of blood concentrations of progesterone
in pregnant and non-pregnant cows constitutes the earliest
means of pregnancy diagnosis in the cow as well as in other
ruminants. It is likely that the anti-luteolytic action of the
conceptus is in fact initiated several days earlier (4).
Arachidonic acid as a luteolytic agent
Te mechanism of the anti-luteolytic action of the fetus
is not known. It is presumably related to metabolism of
arachidonic acid, the precursor to prostaglandin F
2α PGF
(PGF). Hansel et al. (7) isolated arachidonic acid from the
bovine endometrium and demonstrated its luteolytic efect
when injected into the ovarian bursa of pseudo-pregnant
hysterectomized hamsters. Similarly Hofman (8) reported
that intra-peritoneal injections of arachidonic acid were
luteolytic in the pseudo-pregnant rabbit. Based on these
observations it was hypothesized that bovine endometrial
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 7 Bovine luteolysis
tissues might be the source of arachidonic acid, which is then
subsequently converted into prostaglandins by the uterus and
corpus luteum (9).
PGF in uterine vein and endometrial tissue during
the estrous cycle
PGF was measured in plasma obtained from the uterine vein
as well as endometrial tissues at various times during the
bovine estrous cycle (9). Low concentrations of PGF were
measured in the endometrium and uterine venous blood on
day 1-14 of the cycle. Higher values were found at day 15
until the day of estrus, the time that the corpus lutein begins
to regress and plasma progesterone fall. However by the time
of the frst signs of estrous behavior, plasma PGF had already
begun to decline. Tis rise and fall in plasma PGF before the
onset of estrus corresponds with the elevation and decline in
peripheral plasma estradiol (10) which occurs during the 3
days preceding estrus (Figure 1.)
Hormonal regulation of cyclooxygenase-2 (COX-2) in the
bovine endometrium
Expression of cyclooxygenase-2 (COX-2) in the bovine endo-
metrium was demonstrated with plated cells at various stages
of the estrous cycle (11, 12). It was observed that COX-2 was
not consistently expressed throughout the estrous cycle, i.e.,
the signal for COX-2 was strongest prior to luteolysis (15-17
days post- ovulation), weak around estrus and non-existent
in endometrium of ovulation. We next determined the en-
docrine factors that regulate COX-2 and timing of PGF
secretion from the bovine uterus (11). Endometrial cells were
incubated with LH or estradiol. Using western blot analysis it
was found that endometrial COX-2 was increased 2-3 fold by
both LH and estradiol at 2-5 days post-ovulation and at mid-
cycle. In contrast when endometrial cells at ovulation were
used, LH or estradiol resulted in enzyme suppression rather
than stimulation. To demonstrate the correlation between
COX-2 induction and PGF synthesis, endometrial cells were
incubated with arachidonic acid. A signifcant increase in
PGF secretion was observed mid-cycle, prior to luteolysis
and at estrus. However, only a non-statistically signifcant
PGF secretion was observed at ovulation (11).
Hormonal regulation of uterine vein cyclooxygenase
Two hormones were found to control COX-2, LH and estro-
gen (11-14). Incubation of endothelial minces of uterine vein
with LH resulted in 2-fold increase in COX-2 as determined
by western blot analysis. Te increase in cyclooxygenase-2
was maximal in cows in proestrus/estrus compared with
post-ovulatory and luteal phase cows. Activation of the PGF
pathway with activation of PGE2 production by LH was seen
only in the uterine vein. Both PGE2 and PGF production by
vascular tissues increased linearly over 15 hours of incubation
in culture media. Similarly, in a few preparations of uterine
veins where a stimulatory efect of estradiol on PGF was
detected, PGE was not afected.
Pro-estrus rise in estradiol
Te abrupt fall in peripheral plasma progesterone during the
bovine estrous cycle (4, 6) is associated with the induction of
endometrial and uterine vein PGF secretion (9). In addition
to progesterone, there is a pro-estrus rise in plasma estradiol,
whose onset coincides with the precipitous fall in plasma
progesterone. It seems likely that the opposed changes in
the plasma concentrations of these two hormones is associ-
ated with the rise of endometrial and uterine vein PGF, and
induction of luteolysis. Since the onset of behavioral estrus
occurred only after plasma estrogen had passed its peak, it
appears that this neural mediated response of estrogens has
a prolonged latency, or more likely that additional hormone
such as LH, plays a role in its full manifestation (4, 15).
A minor rise in peripheral blood estrogen was observed
on day 4 of the cycle, and a more sustained increase on day 10
to 15 (Shemesh et al., 1972). It is interesting to note that LH
Figure 1: Te fall in peripheral plasma progesterone and increase in
peripheral plasma estrogen is associated with increased level of LHR,
COX-2 and PGF in the endometrium is associated with increased
level of LHR, PGF2α and COX-2 in the uterine vein.
Review Articles
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 Shemesh, M. 8
receptors in the endometrium are more numerous on days
2-5, 15-17 and pro-estrus than on other days of the estrous
cycle. Te ability of estradiol to induce uterine LH receptors
was shown (Ziecik et al., 1992). Te induction of LH recep-
tors by estradiol is of interest as estradiol can induce COX -2
in the bovine endometrium (Freidman et al., 1995, Shemesh
et al., 1996). Tese observations suggest that COX-2 is care-
fully regulated during the estrous cycle and this regulation of
COX-2 is involved in PGF production by endometrial and
uterine vein cells and induction of luteolysis (Shemesh et
al., 1997). Furthermore, the stimulatory efect of mellitin on
PGF secretion at the follicular stages but not on the estrous
cycle suggests that hormonal regulation of uterine COX-2
by estradiol and LH plays a major role in bovine luteolysis.
Te induction of COX-2 by LH and estradiol was shown
to be time-dependent. COX-2 increased linearly during 6
hours of culture and induction of the enzyme occurred within
3-6 hours of culture. Using endometrial cells obtained at
various times of the cycle it was shown that LH and estradiol
can induce COX-2 at 2-5 and 15-17 days post-ovulation,
but inhibit the enzyme in post estrous endometrial cells
(11). A possible explanation is that both LH and estradiol
activate an endometrial protease at ovulation. Furthermore,
LH receptors are more numerous on day 2-5 and 15-17, than
on other days of the estrous cycle (11, 12). Tese actions of
LH, apparently unrelated to its ovulatory peak, indicate that
novel intracellular factors such as COX -2 are involved in
the regulation of prostaglandins production by the uterus.
Role of LH in initiation of luteolysis
Tere is a direct temporal relationship between the induction
of LH receptors, induction of COX-2 and PGF production
(19, 20). Tis indicates a major role for LH in the initiation
of luteolysis. LH binding to the uterine receptors on days 2-4
and 15-17 could afect many systems through LH dependent
cAMP (21) and phosphatidyl inositol (PLC) pathways (22).
Te induction of COX -2 by LH and estradiol may therefore
just represent one of several enzymes induced by LH and
estradiol to regulate the estrous cycle and pregnancy.
Tere is a dichotomy on the concept that LH is involved
in uterine PGF synthesis since traditionally LH is well known
to drive progesterone synthesis by the CL. Our concept is
reasonable considering a decline in plasma progesterone
and rise in circulating LH accompanies a regressing CL.
Importantly Rahe et al. (23) showed there are pulses of LH
during this time frame. However, the temporal increased
expression of the LH receptor in the uterus may be more
signifcant than a rise in plasma LH. Although the role of
LH in luteal regression has not yet been determined, these
preliminary data shows that LH has a profound efect on
PGF synthesis by the uterus and this efect appears to be
limited to a specifc time frame, i.e., middle to late luteal
phase of the cycle. It may well be that rather than an initial
role LH plays in reinforcing luteolysis (Figure 2).
Te objective of the present review is to provide an
overview of the physiological role of Lutenizing Hormone
Receptors (LHR) in the regression of the CL. We also
provided an insight to the relationship between blood pro-
gesterone, estradiol, LH and uterine cyclooxygenase and PGF
during the regression of the CL. Prior to our work, extra-
gonadal LHRs were considered as non-functional receptors.
However, we demonstrated that LHR in the uterus regulates
the bovine uterine cyclooxygenase and uterine PGF which
is known to be associated with induction of bovine (14) and
porcine luteolysis (24, 25). Cervical LH and FSH receptors
can also regulate cervical cyclooxygenase to produce PGE2
in the bovine (25, 26), porcine (25) and ovine (28) cervices.
Te up regulation of uterine PGs by gonadotropins may
have use in clinical practice of veterinary medicine as the
gonadotrophins can used for cervical relaxation (29-31) and,
in conjunction with embryonic factors, may lead to improve
reproductive efciency in domestic species (32).
In future studies, we intend to use a novel Si RNA we
developed for inhibiting COX-2 (33). Tis Si RNA will be
used in vitro and in vivo to inhibit the expression of uterine
LHR and determine the efects on the levels of COX-2 and
PGs throughout the estrous cycle.
Figure 2: LH acts to increase progesterone synthesis to prolong the
lifespan of the CL but can also be involved in regression of the CL by
increasing PGF production in the uterine vein.
Review Articles
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 9 Bovine luteolysis
CONFLICT OF INTERESTS
Tis review did not receive any specifc grant from any fund-
ing agency in the public, commercial or not-for-proft sector.
Tere is no confict of interest that could be perceived as
prejudicing the impartiality of this review.
REFERENCES
1. Donaldson, L.E., Basset, J.M. and Torburn, G.D.: Peripheral
plasma progesterone concentrations of cows during puberty, oes-
trous cycles, pregnancy and lactation, and the efect of under-
nutrition or exogenous oxytocin on progesterone concentration.
J. Endocrinol. 48: 599-614, 1970.
2. Wendorf, G.L., Lawyer, M.S. and First, N.L.: Role of the adrenals
in the maintenance of pregnancy in cows. J. Reprod. Fert. 68:
281-287, 1983.
3. Shemesh, M.: Production and regulation of progesterone in bovine
corpus luteum and placenta in mid and late gestation: a personal
review. Reprod. Fertil. Dev. 2: 129 -135, 1990.
4. Shemesh, M. Ayalon, N. and Lindner, H.R.: Early efect of con-
ceptus on plasma progesterone level of the cow. J. Reprod. Fertil.
15: 161-164, 1968.
5. Shemesh, M., Ayalon, N. and Lindner, H.R.: Plasma progester-
one concentration of dairy cow during the oestrus cycle. Refuah
Veterinarit. 25: 265-270, 1969.
6. Shemesh, M., Lindner, H.R. and Ayalon, N.: Afnity competitive
protein-binding assay of progesterone in bovine jugular venous
plasma during the estrous cycle. J. Reprod. Fertil. 25: 167-174,
1971.
7. Hansel, W., Shemesh, M., Hixon, J. and, Lukaszewska, J.: Ex-
traction, isolation and identifcation of luteolytic substance from
bovine endometrium. Biol. Reprod. 13: 448-452, 1975.
8. Hofman, L.H.: Luteal regression induced by arachidonic acid in
the pseudopregnant rabbit. J. Reprod. Fertil. 36, 401-404. 1974.
9. Shemesh, M. and Hansel, W.: Levels of prostaglandins (PGF) in
bovine endometrium, uterine venous, ovarian arterial and jugu-
lar plasma during the estrous cycle. Proc. Soc. Exper. Bio. 148:
123-126, 1975.
10. Shemesh, M., Ayalon, N. and Lindner, H.R.: Oestradiol levels in
the peripheral blood of cows during the oestrous cycle. J. Endo-
crinol. 55: 73-78, 1972.
11. Shemesh, M., Freidman, S., Harel-Markowitz, E. and Gurevich,
M.: Induction and regulation of the cyclooxygenase in the bovine
endometrium. In: Zor M (ed). Lipid Mediators in Health and
Disease. Tel Aviv, Israel, Freund Publishing House Ltd., pp.
71-78, 1994.
12. Freidman, S., Gurevich, M. and Shemesh, M.: Bovine cyclic endo-
metrium contains high-afnity luteinizing hormone/human cho-
rionic gonadotropin binding sites. Biol. Reprod. 15: 1020-1026,
1995.
13. Shemesh, M.: Actions of gonadotrophins on the uterus. Reproduc-
tion. 121: 835-842, 2001.
14. Fields, M.J. and Shemesh, M.: Extra gonadal luteinizing hormone
receptors in the reproductive tract of domestic animals. Biol. Re-
prod. 71: 1412-1418, 2004.
15. Mondal, M., Rajkhowa, C. and Prakash, B.S.: Relationship of
plasma estradiol-17beta, total estrogen, and progesterone to estrus
behavior in mithun (Bos frontalis) cows. Horm. Behav. 49: 626-
633, 2006.
16. Ziecik, A.J., Jedlinska, M. and Rzucidlo, S.J.: Efect of estradiol
and progesterone on myometrial LH/hCG receptors in pigs. Acta
Endocrinol. 127: 185-188, 1992.
17. Shemesh, M., Friedman, S., Gurevich, M., Stram, Y., Fields, M.
and Shore, L.S.: Luteinizing hormone receptors and its mRNA in
the bovine endometrium. J. Physiol. Pharmacol. 47 (Supplement
1): 15-27, 1996.
18. Shemesh, M., Gurevich, M., Mizrachi, D., Dombrovski, L., Stram
Y., Fields M.J. and Shore L.: Expression of functional luteinizing
hormone (LH) receptor and its messenger ribonucleic acid in
bovine uterine veins: LH induction of cyclooxygenase and aug-
mentation of prostaglandin production in bovine uterine veins.
Endocrinology. 138: 4844-4851, 1997.
19. Shemesh, M., Mizrachi, D., Gurevich, M., Shore, L.S., Reed, J.,
Chang, S-M.T., Tatcher, W.W. and Fields, M.J.: Expression of
functional luteinizing hormone (LH) receptor and its messenger
ribonucleic acid in bovine endometrium: LH augmentation of
cAMP and inositol phosphate in vitro and human chorionic
gonadotropin (hCG) augmentation of peripheral prostaglandin
in vivo. Reprod. Biol. 1: 13-32, 2001.
20. Shemesh, M., Mizrachi, D., Gurevich, M., Shore, L.S., Reed J.,
Chang, S-M.T., Tatcher, W.W. and Fields, M.J.: Expression of
functional luteinizing hormone (LH) receptor and its messenger
ribonucleic acid in bovine endometrium: LH augmentation of
cAMP and inositol phosphate in vitro and human chorionic
gonadotropin (hCG) augmentation of peripheral prostaglandin
in vivo. Reprod. Biol. 1: 13-32, 2002.
21. Marsh, J.M.: Te role of cyclic AMP in gonadal function. In:
Greengard, P. and Robinson G.A. (Eds.) Advances in Cyclic
Nucleotde Research, Vol. 6. Raven Press, NY. pp. 138-199, 1975.
22. Davis, J.S.: Stimulation of intracellular free Ca
+
by luteinizing
hormone in isolated bovine luteal cells. Adv. Exp. Med. Biol. 219:
671-675, 1987.
23. Rahe, C.H., Owens, R.E., Fleeger, J.L., Newton, H.J. and Harms,
P.G.: Pattern of plasma luteinizing hormone in the cyclic cow:
Dependence upon the period of the cycle. Endocrinol. 107: 498-
503, 1980.
24. Stepien, A., Derecka, K., Gawronska, B., Bodek, G., Zwierzchows-
ki, L., Shemesh, M. and Ziecik, A.J.: LH/hCG receptors in the
porcine uterus – a new evidence of their presence in the cervix J.
Physiol. Pharm. 51: 917-931, 2000.
25. Stepien, A., Shemesh, M. and Ziecik, A.J.: Luteinising hormone
receptor kinetic and LH-induced prostaglandin production
throughout the oestrous cycle in porcine endometrium Reprod.
Nutr. Dev. 39: 663-674, 1999.
26. Mizrachi, D. and Shemesh, M.: Expression of functional lute-
inising hormone receptor and its messenger ribonucleic acid in
bovine cervix: luteinising hormone augmentation of intracellular
cyclic AMP, phosphate inositol and cyclooxygenase. Mol. Cell.
Endocrinol. 157: 191-200, 1999.
27. Mizrachi, D. and Shemesh, M.: Follicle-stimulating hormone
receptor and its messenger ribonucleic acid are present in the
Review Articles
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 Shemesh, M. 10
bovine cervix and can regulate cervical prostanoid synthesis. Biol.
Reprod. 61: 776-841, 1999.
28. Leethongdee, S., Khalid, M. and Scaramuzzi, R.J.: Te efect of
the intracervical application of follicle-stimulating hormone or
luteinizing hormone on the pattern of expression of gonadotrophin
receptors in the cervix of non-pregnant ewes. Reprod. Domest.
Anim. 49: 568-75, 2014.
29. Leethongdee, S., Kershaw-Young, C.M., Scaramuzzi, R.J. and
Khalid, M.: Intra-cervical application of Misoprostol at estrus
alters the content of cervical hyaluronan and the mRNA expres-
sion of follicle stimulating hormone receptor (FSHR), lutein-
izing hormone receptor (LHR) and cyclooxygenase-2 in the ewe.
Teriogenol. 73: 1257-66, 2010.
30. Leethongdee, S., Khalid, M., Bhatti, A., Ponglowhapan, S., Ker-
shaw, C.M. and Scaramuzzi, R.J.: Te efects of the prostaglandin
E analogue Misoprostol and follicle-stimulating hormone on
cervical penetrability in ewes during the peri-ovulatory period.
Teriogenol. 67: 767-77, 2007.
31. Ponglowhapan, S. and Leethongdee, S.: Luteinizing hormone
and follicle stimulating hormone receptors: Functions and clinical
implications in extra-gonadal tissues. Tai J. Vet. Med. Suppl. 1,
44: 93-97, 2014.
32. Ziecik, A.J., Bodek, G., Blitek, A., Kaczmarek, M. and Waclawik,
A.: Nongonadal LH receptors, their involvement in female re-
productive function and a new applicable approach. Vet. J. 169:
75-84, 2005.
33. Xiuzhu, T., Shore, L., Stram, Y., Michaeli, S., Brietbart, H. and
Shemesh, M.: Duplexes of 21 nucleotide RNA specifc for COX
II mediates RNA interference in cultured bovine aortic coronary
endothelial cells (BAECs). Prostagl. Lipid Mediators. 71: 119-129,
2003.
Review Articles
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 Shemesh, M. 6
Induction of Uterine Cyclooxygenase by Leutenizing Hormone and
Estradiol is an Important Determinant of Bovine Luteolysis
Shemesh, M.,
1
Shore, L.S.,
1
Fields, M.J.
2
and Hansel, W.
3
1
Kimron Veterinary Institute, Bet Dagan, Israel 50250.
2
University of Florida, Gainesville, FL 32611, United States of America.
3
Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA, 70808,
United States of America.
*
Corresponding Author: Prof. Mordechai Shemesh, Kimron Veterinary Institute, Bet Dagan, Israel 50250. E-mail: mordechai.shemesh@mail.huji.ac.il
ABSTRACT
Termination of the functional bovine corpus luteum is associated with a precipitous fall in peripheral plasma
progesterone which is induced by a pulsatile release of prostaglandin F
2α (PGF) from the late luteal phase
uterus. Te production of uterine PGF from arachidonic acid is greatest in endometrial cells 2-5 and 15– 17
days post-ovulation. Similarly exposure of uterine endometrial cells to estradiol 17β or to lutenizing hormone
(LH) results in a signifcant increase in LH receptors, cyclooxygenase-2 (COX-2) and PGF at 2-5 and 15-
17 days post-ovulation. It is therefore suggested that hormonal regulation of uterine COX- 2 by pulses of
estradiol and LH may play a role in bovine luteolysis.
Keywords: Lutelysis; COX-2; Lutenizing Hormone; Prostaglandin F2α
REVIEW
Events associated with regression of the bovine
corpus luteum (CL)
Tis review presents an overview of research carried out in
our laboratory over some forty years associated with the
subject of the regression of the bovine CL.
Peripheral plasma of progesterone
Peripheral plasma concentrations of progesterone are a valu-
able indication of the concentration of hormone reaching
target organs and control centers governing secretion of
gonadotropins at various phases of the reproductive cycle.
Alterations in circulating progesterone also supplies informa-
tion regarding the functional state of the corpus luteum (CL)
or of alternative sources of the hormone such as the adrenal
or placenta (1-3).
In our early work (4-6), we demonstrated that in the
absence of an early embryo in the uterus, there is a precipitous
fall in luteal progesterone secretion toward day 18-19 of the
cycle. Tis divergence of blood concentrations of progesterone
in pregnant and non-pregnant cows constitutes the earliest
means of pregnancy diagnosis in the cow as well as in other
ruminants. It is likely that the anti-luteolytic action of the
conceptus is in fact initiated several days earlier (4).
Arachidonic acid as a luteolytic agent
Te mechanism of the anti-luteolytic action of the fetus
is not known. It is presumably related to metabolism of
arachidonic acid, the precursor to prostaglandin F
2α PGF
(PGF). Hansel et al. (7) isolated arachidonic acid from the
bovine endometrium and demonstrated its luteolytic efect
when injected into the ovarian bursa of pseudo-pregnant
hysterectomized hamsters. Similarly Hofman (8) reported
that intra-peritoneal injections of arachidonic acid were
luteolytic in the pseudo-pregnant rabbit. Based on these
observations it was hypothesized that bovine endometrial
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 7 Bovine luteolysis
tissues might be the source of arachidonic acid, which is then
subsequently converted into prostaglandins by the uterus and
corpus luteum (9).
PGF in uterine vein and endometrial tissue during
the estrous cycle
PGF was measured in plasma obtained from the uterine vein
as well as endometrial tissues at various times during the
bovine estrous cycle (9). Low concentrations of PGF were
measured in the endometrium and uterine venous blood on
day 1-14 of the cycle. Higher values were found at day 15
until the day of estrus, the time that the corpus lutein begins
to regress and plasma progesterone fall. However by the time
of the frst signs of estrous behavior, plasma PGF had already
begun to decline. Tis rise and fall in plasma PGF before the
onset of estrus corresponds with the elevation and decline in
peripheral plasma estradiol (10) which occurs during the 3
days preceding estrus (Figure 1.)
Hormonal regulation of cyclooxygenase-2 (COX-2) in the
bovine endometrium
Expression of cyclooxygenase-2 (COX-2) in the bovine endo-
metrium was demonstrated with plated cells at various stages
of the estrous cycle (11, 12). It was observed that COX-2 was
not consistently expressed throughout the estrous cycle, i.e.,
the signal for COX-2 was strongest prior to luteolysis (15-17
days post- ovulation), weak around estrus and non-existent
in endometrium of ovulation. We next determined the en-
docrine factors that regulate COX-2 and timing of PGF
secretion from the bovine uterus (11). Endometrial cells were
incubated with LH or estradiol. Using western blot analysis it
was found that endometrial COX-2 was increased 2-3 fold by
both LH and estradiol at 2-5 days post-ovulation and at mid-
cycle. In contrast when endometrial cells at ovulation were
used, LH or estradiol resulted in enzyme suppression rather
than stimulation. To demonstrate the correlation between
COX-2 induction and PGF synthesis, endometrial cells were
incubated with arachidonic acid. A signifcant increase in
PGF secretion was observed mid-cycle, prior to luteolysis
and at estrus. However, only a non-statistically signifcant
PGF secretion was observed at ovulation (11).
Hormonal regulation of uterine vein cyclooxygenase
Two hormones were found to control COX-2, LH and estro-
gen (11-14). Incubation of endothelial minces of uterine vein
with LH resulted in 2-fold increase in COX-2 as determined
by western blot analysis. Te increase in cyclooxygenase-2
was maximal in cows in proestrus/estrus compared with
post-ovulatory and luteal phase cows. Activation of the PGF
pathway with activation of PGE2 production by LH was seen
only in the uterine vein. Both PGE2 and PGF production by
vascular tissues increased linearly over 15 hours of incubation
in culture media. Similarly, in a few preparations of uterine
veins where a stimulatory efect of estradiol on PGF was
detected, PGE was not afected.
Pro-estrus rise in estradiol
Te abrupt fall in peripheral plasma progesterone during the
bovine estrous cycle (4, 6) is associated with the induction of
endometrial and uterine vein PGF secretion (9). In addition
to progesterone, there is a pro-estrus rise in plasma estradiol,
whose onset coincides with the precipitous fall in plasma
progesterone. It seems likely that the opposed changes in
the plasma concentrations of these two hormones is associ-
ated with the rise of endometrial and uterine vein PGF, and
induction of luteolysis. Since the onset of behavioral estrus
occurred only after plasma estrogen had passed its peak, it
appears that this neural mediated response of estrogens has
a prolonged latency, or more likely that additional hormone
such as LH, plays a role in its full manifestation (4, 15).
A minor rise in peripheral blood estrogen was observed
on day 4 of the cycle, and a more sustained increase on day 10
to 15 (Shemesh et al., 1972). It is interesting to note that LH
Figure 1: Te fall in peripheral plasma progesterone and increase in
peripheral plasma estrogen is associated with increased level of LHR,
COX-2 and PGF in the endometrium is associated with increased
level of LHR, PGF2α and COX-2 in the uterine vein.
Review Articles
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 Shemesh, M. 8
receptors in the endometrium are more numerous on days
2-5, 15-17 and pro-estrus than on other days of the estrous
cycle. Te ability of estradiol to induce uterine LH receptors
was shown (Ziecik et al., 1992). Te induction of LH recep-
tors by estradiol is of interest as estradiol can induce COX -2
in the bovine endometrium (Freidman et al., 1995, Shemesh
et al., 1996). Tese observations suggest that COX-2 is care-
fully regulated during the estrous cycle and this regulation of
COX-2 is involved in PGF production by endometrial and
uterine vein cells and induction of luteolysis (Shemesh et
al., 1997). Furthermore, the stimulatory efect of mellitin on
PGF secretion at the follicular stages but not on the estrous
cycle suggests that hormonal regulation of uterine COX-2
by estradiol and LH plays a major role in bovine luteolysis.
Te induction of COX-2 by LH and estradiol was shown
to be time-dependent. COX-2 increased linearly during 6
hours of culture and induction of the enzyme occurred within
3-6 hours of culture. Using endometrial cells obtained at
various times of the cycle it was shown that LH and estradiol
can induce COX-2 at 2-5 and 15-17 days post-ovulation,
but inhibit the enzyme in post estrous endometrial cells
(11). A possible explanation is that both LH and estradiol
activate an endometrial protease at ovulation. Furthermore,
LH receptors are more numerous on day 2-5 and 15-17, than
on other days of the estrous cycle (11, 12). Tese actions of
LH, apparently unrelated to its ovulatory peak, indicate that
novel intracellular factors such as COX -2 are involved in
the regulation of prostaglandins production by the uterus.
Role of LH in initiation of luteolysis
Tere is a direct temporal relationship between the induction
of LH receptors, induction of COX-2 and PGF production
(19, 20). Tis indicates a major role for LH in the initiation
of luteolysis. LH binding to the uterine receptors on days 2-4
and 15-17 could afect many systems through LH dependent
cAMP (21) and phosphatidyl inositol (PLC) pathways (22).
Te induction of COX -2 by LH and estradiol may therefore
just represent one of several enzymes induced by LH and
estradiol to regulate the estrous cycle and pregnancy.
Tere is a dichotomy on the concept that LH is involved
in uterine PGF synthesis since traditionally LH is well known
to drive progesterone synthesis by the CL. Our concept is
reasonable considering a decline in plasma progesterone
and rise in circulating LH accompanies a regressing CL.
Importantly Rahe et al. (23) showed there are pulses of LH
during this time frame. However, the temporal increased
expression of the LH receptor in the uterus may be more
signifcant than a rise in plasma LH. Although the role of
LH in luteal regression has not yet been determined, these
preliminary data shows that LH has a profound efect on
PGF synthesis by the uterus and this efect appears to be
limited to a specifc time frame, i.e., middle to late luteal
phase of the cycle. It may well be that rather than an initial
role LH plays in reinforcing luteolysis (Figure 2).
Te objective of the present review is to provide an
overview of the physiological role of Lutenizing Hormone
Receptors (LHR) in the regression of the CL. We also
provided an insight to the relationship between blood pro-
gesterone, estradiol, LH and uterine cyclooxygenase and PGF
during the regression of the CL. Prior to our work, extra-
gonadal LHRs were considered as non-functional receptors.
However, we demonstrated that LHR in the uterus regulates
the bovine uterine cyclooxygenase and uterine PGF which
is known to be associated with induction of bovine (14) and
porcine luteolysis (24, 25). Cervical LH and FSH receptors
can also regulate cervical cyclooxygenase to produce PGE2
in the bovine (25, 26), porcine (25) and ovine (28) cervices.
Te up regulation of uterine PGs by gonadotropins may
have use in clinical practice of veterinary medicine as the
gonadotrophins can used for cervical relaxation (29-31) and,
in conjunction with embryonic factors, may lead to improve
reproductive efciency in domestic species (32).
In future studies, we intend to use a novel Si RNA we
developed for inhibiting COX-2 (33). Tis Si RNA will be
used in vitro and in vivo to inhibit the expression of uterine
LHR and determine the efects on the levels of COX-2 and
PGs throughout the estrous cycle.
Figure 2: LH acts to increase progesterone synthesis to prolong the
lifespan of the CL but can also be involved in regression of the CL by
increasing PGF production in the uterine vein.
Review Articles
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 9 Bovine luteolysis
CONFLICT OF INTERESTS
Tis review did not receive any specifc grant from any fund-
ing agency in the public, commercial or not-for-proft sector.
Tere is no confict of interest that could be perceived as
prejudicing the impartiality of this review.
REFERENCES
1. Donaldson, L.E., Basset, J.M. and Torburn, G.D.: Peripheral
plasma progesterone concentrations of cows during puberty, oes-
trous cycles, pregnancy and lactation, and the efect of under-
nutrition or exogenous oxytocin on progesterone concentration.
J. Endocrinol. 48: 599-614, 1970.
2. Wendorf, G.L., Lawyer, M.S. and First, N.L.: Role of the adrenals
in the maintenance of pregnancy in cows. J. Reprod. Fert. 68:
281-287, 1983.
3. Shemesh, M.: Production and regulation of progesterone in bovine
corpus luteum and placenta in mid and late gestation: a personal
review. Reprod. Fertil. Dev. 2: 129 -135, 1990.
4. Shemesh, M. Ayalon, N. and Lindner, H.R.: Early efect of con-
ceptus on plasma progesterone level of the cow. J. Reprod. Fertil.
15: 161-164, 1968.
5. Shemesh, M., Ayalon, N. and Lindner, H.R.: Plasma progester-
one concentration of dairy cow during the oestrus cycle. Refuah
Veterinarit. 25: 265-270, 1969.
6. Shemesh, M., Lindner, H.R. and Ayalon, N.: Afnity competitive
protein-binding assay of progesterone in bovine jugular venous
plasma during the estrous cycle. J. Reprod. Fertil. 25: 167-174,
1971.
7. Hansel, W., Shemesh, M., Hixon, J. and, Lukaszewska, J.: Ex-
traction, isolation and identifcation of luteolytic substance from
bovine endometrium. Biol. Reprod. 13: 448-452, 1975.
8. Hofman, L.H.: Luteal regression induced by arachidonic acid in
the pseudopregnant rabbit. J. Reprod. Fertil. 36, 401-404. 1974.
9. Shemesh, M. and Hansel, W.: Levels of prostaglandins (PGF) in
bovine endometrium, uterine venous, ovarian arterial and jugu-
lar plasma during the estrous cycle. Proc. Soc. Exper. Bio. 148:
123-126, 1975.
10. Shemesh, M., Ayalon, N. and Lindner, H.R.: Oestradiol levels in
the peripheral blood of cows during the oestrous cycle. J. Endo-
crinol. 55: 73-78, 1972.
11. Shemesh, M., Freidman, S., Harel-Markowitz, E. and Gurevich,
M.: Induction and regulation of the cyclooxygenase in the bovine
endometrium. In: Zor M (ed). Lipid Mediators in Health and
Disease. Tel Aviv, Israel, Freund Publishing House Ltd., pp.
71-78, 1994.
12. Freidman, S., Gurevich, M. and Shemesh, M.: Bovine cyclic endo-
metrium contains high-afnity luteinizing hormone/human cho-
rionic gonadotropin binding sites. Biol. Reprod. 15: 1020-1026,
1995.
13. Shemesh, M.: Actions of gonadotrophins on the uterus. Reproduc-
tion. 121: 835-842, 2001.
14. Fields, M.J. and Shemesh, M.: Extra gonadal luteinizing hormone
receptors in the reproductive tract of domestic animals. Biol. Re-
prod. 71: 1412-1418, 2004.
15. Mondal, M., Rajkhowa, C. and Prakash, B.S.: Relationship of
plasma estradiol-17beta, total estrogen, and progesterone to estrus
behavior in mithun (Bos frontalis) cows. Horm. Behav. 49: 626-
633, 2006.
16. Ziecik, A.J., Jedlinska, M. and Rzucidlo, S.J.: Efect of estradiol
and progesterone on myometrial LH/hCG receptors in pigs. Acta
Endocrinol. 127: 185-188, 1992.
17. Shemesh, M., Friedman, S., Gurevich, M., Stram, Y., Fields, M.
and Shore, L.S.: Luteinizing hormone receptors and its mRNA in
the bovine endometrium. J. Physiol. Pharmacol. 47 (Supplement
1): 15-27, 1996.
18. Shemesh, M., Gurevich, M., Mizrachi, D., Dombrovski, L., Stram
Y., Fields M.J. and Shore L.: Expression of functional luteinizing
hormone (LH) receptor and its messenger ribonucleic acid in
bovine uterine veins: LH induction of cyclooxygenase and aug-
mentation of prostaglandin production in bovine uterine veins.
Endocrinology. 138: 4844-4851, 1997.
19. Shemesh, M., Mizrachi, D., Gurevich, M., Shore, L.S., Reed, J.,
Chang, S-M.T., Tatcher, W.W. and Fields, M.J.: Expression of
functional luteinizing hormone (LH) receptor and its messenger
ribonucleic acid in bovine endometrium: LH augmentation of
cAMP and inositol phosphate in vitro and human chorionic
gonadotropin (hCG) augmentation of peripheral prostaglandin
in vivo. Reprod. Biol. 1: 13-32, 2001.
20. Shemesh, M., Mizrachi, D., Gurevich, M., Shore, L.S., Reed J.,
Chang, S-M.T., Tatcher, W.W. and Fields, M.J.: Expression of
functional luteinizing hormone (LH) receptor and its messenger
ribonucleic acid in bovine endometrium: LH augmentation of
cAMP and inositol phosphate in vitro and human chorionic
gonadotropin (hCG) augmentation of peripheral prostaglandin
in vivo. Reprod. Biol. 1: 13-32, 2002.
21. Marsh, J.M.: Te role of cyclic AMP in gonadal function. In:
Greengard, P. and Robinson G.A. (Eds.) Advances in Cyclic
Nucleotde Research, Vol. 6. Raven Press, NY. pp. 138-199, 1975.
22. Davis, J.S.: Stimulation of intracellular free Ca
+
by luteinizing
hormone in isolated bovine luteal cells. Adv. Exp. Med. Biol. 219:
671-675, 1987.
23. Rahe, C.H., Owens, R.E., Fleeger, J.L., Newton, H.J. and Harms,
P.G.: Pattern of plasma luteinizing hormone in the cyclic cow:
Dependence upon the period of the cycle. Endocrinol. 107: 498-
503, 1980.
24. Stepien, A., Derecka, K., Gawronska, B., Bodek, G., Zwierzchows-
ki, L., Shemesh, M. and Ziecik, A.J.: LH/hCG receptors in the
porcine uterus – a new evidence of their presence in the cervix J.
Physiol. Pharm. 51: 917-931, 2000.
25. Stepien, A., Shemesh, M. and Ziecik, A.J.: Luteinising hormone
receptor kinetic and LH-induced prostaglandin production
throughout the oestrous cycle in porcine endometrium Reprod.
Nutr. Dev. 39: 663-674, 1999.
26. Mizrachi, D. and Shemesh, M.: Expression of functional lute-
inising hormone receptor and its messenger ribonucleic acid in
bovine cervix: luteinising hormone augmentation of intracellular
cyclic AMP, phosphate inositol and cyclooxygenase. Mol. Cell.
Endocrinol. 157: 191-200, 1999.
27. Mizrachi, D. and Shemesh, M.: Follicle-stimulating hormone
receptor and its messenger ribonucleic acid are present in the
Review Articles
Israel Journal of Veterinary Medicine Vol. 70 (4) December 2015 Shemesh, M. 10
bovine cervix and can regulate cervical prostanoid synthesis. Biol.
Reprod. 61: 776-841, 1999.
28. Leethongdee, S., Khalid, M. and Scaramuzzi, R.J.: Te efect of
the intracervical application of follicle-stimulating hormone or
luteinizing hormone on the pattern of expression of gonadotrophin
receptors in the cervix of non-pregnant ewes. Reprod. Domest.
Anim. 49: 568-75, 2014.
29. Leethongdee, S., Kershaw-Young, C.M., Scaramuzzi, R.J. and
Khalid, M.: Intra-cervical application of Misoprostol at estrus
alters the content of cervical hyaluronan and the mRNA expres-
sion of follicle stimulating hormone receptor (FSHR), lutein-
izing hormone receptor (LHR) and cyclooxygenase-2 in the ewe.
Teriogenol. 73: 1257-66, 2010.
30. Leethongdee, S., Khalid, M., Bhatti, A., Ponglowhapan, S., Ker-
shaw, C.M. and Scaramuzzi, R.J.: Te efects of the prostaglandin
E analogue Misoprostol and follicle-stimulating hormone on
cervical penetrability in ewes during the peri-ovulatory period.
Teriogenol. 67: 767-77, 2007.
31. Ponglowhapan, S. and Leethongdee, S.: Luteinizing hormone
and follicle stimulating hormone receptors: Functions and clinical
implications in extra-gonadal tissues. Tai J. Vet. Med. Suppl. 1,
44: 93-97, 2014.
32. Ziecik, A.J., Bodek, G., Blitek, A., Kaczmarek, M. and Waclawik,
A.: Nongonadal LH receptors, their involvement in female re-
productive function and a new applicable approach. Vet. J. 169:
75-84, 2005.
33. Xiuzhu, T., Shore, L., Stram, Y., Michaeli, S., Brietbart, H. and
Shemesh, M.: Duplexes of 21 nucleotide RNA specifc for COX
II mediates RNA interference in cultured bovine aortic coronary
endothelial cells (BAECs). Prostagl. Lipid Mediators. 71: 119-129,
2003.
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