Functional importance of bovine myometrial and vascular LH receptors and cervical FSH receptors

transcript

Mordechai Shemesh, M.D.,1 Dario Mizrachi, M.D.,1 Michael Gurevich, M.D.,1Yehuda Stram, M.D.,2 Laurence S. Shore, M.D.,1 and Michael J. Fields, M.D.3

ABSTRACT

Bovine myometrium and cervix contain luteinizing hormone/human chorionicgonadotropin (LH/hCG) binding sites, LH receptor (LH-R) messenger RNA (mRNA),and LH-R protein. Expression ofLH-R is dependent on the stage of the cycle. LH-Rexpression is high during the luteal phase but weak during the follicular phase. In bothmyometrium and cervix, LH activates both the adenylate cyclase and phospholipase Cpathways, and the effect of LH on both pathways at each stage of the cycle is correlatedwith the amount of LH- R present in the tissue. Because activation of cyclic AMP(cAMP) is associated with myometrial quiescence, we suggest that LH activation of uter-ine cAMP could serve to keep the uterus quiescent during the luteal phase. On the otherhand, in the uterine vein LH-R mRNA and LH-R are maximal during preestrus/estrusas opposed to the luteal phase. In the uterine vein, LH increases the expression of cy-clooxygenase and production of both prostaglandin E2 (PGE2) and PGF2a. BecausePGF 2a is the physiologicalluteolytic signal in the cow, we suggest that this increase inprostaglandin production by the uterine vein is part of the physiological events leading toluteolysis. In addition to uterine LH -R, the bovine cervix at preestrus/ estrus has high lev-els of follicle-stimulating hormone receptor (FSH- R) and its corresponding mRNA.As with LH-R, activation ofFSH-R by FSH is associated with activation ofa G pro-tein-coupled receptor family that mediates the cAMP and inositol phosphate signalingpathways. Activation of these signaling pathways is associated with an increase in the ex-pression of cyclooxygenase and production of PGE2. Because expression of the FSH re-ceptor was maximal at the time of the FSH peak in the blood, we suggest a physiologicalrole for FSH in the cervix relaxation and opening at estrus.

KEYWORDS: Myometrium, LH, LH receptors, bovine

Luteinizing hormone/human chorionic go-nadotropin (LH/hCG) receptors are present in the uteriof several species including human,l rat,2 rabbit,3 andpig.4.5 They are also present in the human placenta, fetalmembrane, and decidual and have been characterized inhuman endometrial and myometrial vascular smoothmuscle.6 Furthermore, the endothelia of these blood

vessels express hCG/hLH receptor messenger RNA(mRNA) and immunoreactive receptor protein6 andcontain high concentrations of cyclooxygenase in boththe human6 and sheep.7

In the bovine, LH receptor (LH-R) mRNAand LH-R protein are present in the cervix,8 uterinevein,9 and myometrium (Figs. i and 2). The estrous

Seminars in Reproductive Medicine, Volume 19, Number 1, 2001. Reprint requests: Dr. Shemesh, Department of Hormone Research, KimronVeterinary Institute, Bet Dagan, POB 12, Israel 50250. Departments of lHormone Research and 2Virology, Kimron Veterinary Institute, BetDagan, Israel and 3 Animal Science Department, University of Florida, Gainesville, Florida. Copyright @ 2001 by Thieme Medical Publishers,

Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.1526-8004,p;2001,19,01,087,096,ftx,en;sreO0106x.

88 SEMINARS IN REPRODUCTIVE MEDICINE/VOLUME 19, NUMBER 1 2001

552 bp

1 2 3 4 5 6 7 8 9 1011 12

Figure 1 Reverse transcription-polymerase chain reaction (RT-PCR) amplification of bovine myometrium LH-R mRNA. Myome-trium was taken from different stages of the estrous cycle. PCR amplification product for LH-R (estimated 552 bp) was obtained aspreviously described.8 RT-PCR was performed using 2 IJ.g of total RNA of corpus luteum (positive control; lane 1 ), negative control(lane 2, no RNA), myometrial tissue from postovulatory (lanes 3-5), luteal (lanes 6-8), and preestrus/estrus (lanes 9-12) phases.

cycle in cow is 21 days and can be divided intopreestrus (days 18-20)/ estrus (day 0), postovulatory(days 1-4), and luteal (days 12-16) based on the sizeand color of the corpus luteum. In the cervix and

myometrium, the expression of LH -R protein ismaximal during the luteal phase, whereas in thevein LH-R protein is maximally expressed during

preestrus/estrus (Fig. 3).

0 Figure 2 Expression of myometrial LH-R inmyometrium. Forty five micrograms of pro-tein of soluble extract was analyzed for LH-Rby Western blot using rat anti-LH-R antibodyas previously described.B Western blotshows LH-R level in myometrial tissues frompostovulatory (days 1-4), luteal (days 12-16),

preestrus/estrus (days 18-20) myometrium.The histogram rep~esents the relative opticaldensity value at each stage of the cycle(n = 7) compared with the average optical

density at preestrus/estrus. Columns withdifferent letters differ significantly from eachother (P <.05).

Postovuhtory Luteal Pre-estnW &trm

93KD --+

Postovulatory Luteal Pre-estrus/

estrus

89MYOMETRIAL LH RECEPTORS/SHEMESH ET AL

LH-RLevel

ern blot analysis to detect mature 93-kDa LH-R inbovine corpus luteum, cervix,8 and uterine vein,9 thesize of the LH- R protein on sodium dodecyl sulfate gelsappeared to be the same in all of the bovine reproduc-tive tract tissues tested. This 93-kDa protein appears tobe very similar to that found in the rat ovary.l0,1l

LH may up-regulate its own receptor. LH in-creases the expression of its own receptor in the cervix8and myometrium (Fig. 4) during the luteal phase in amanner similar to regulation of LH -R in rat ovary}2 Thiscould be the result of either de novo synthesis or stabiliza-tion of the ligand. However, we have previously reportedthat the increase in cyclooxygenase in bovine tissues undersimilar conditions is due to de novo synthesis}3

Postovulatory Luteal Pre-estruslEstrus

LH ACTIVATION OF ADENYLATE CYCLASEAND INOSITOL PHOSPHATEActivation of the adenylate cyclase pathway in thecervixs and myometrium (Fig. 5) by LH was inducedwithin 10 minutes. LH increased cyclic AMP (cAMP)production by cervical tissues and myometrium (Fig. 5)in the luteal phase and had a reducing or nondetectableeffect in preestrusl estrus and the postovulatory period.On the other hand, forskolin activated cAMP at allstages tested.

The gene for LH-R is the same in bovine cervix,myometrium, and vein. The nucleotide sequence ho-mology of the LH-R found in the cervix, myometrium,and uterine vein8,9 is 99.3% identical to the comparableregion of bovine LH-R from the corpus luteum. Whenthe same antibody (anti-rat LH-R) was used for West-

~>~.!~

0 10 20 50

LH (ng/ml)Figure 4 Effect of LH in vitro on expressionof its own receptor (93 kDa) in bovine myo-metria! tissue. Tissues were taken from fiveluteal phase cows and incubated (four 25-mgaliquots) in the absence or presence of LH(10 to 50 ng/mU for 180 minutes. Forty-fivemicrogram aliquots of protein were used forthe Western blots using rat anti-LH receptoras described previous!y.8 * p <.05.

93 KD +.~;j

CorpusLuteum

Control LH

20 ng/ml

Figure 3 Schematic representation of LH-R concentration inreproductive tissues during the bovine estrous cycle.

0..~'5

O LH 5 nglml

~ LH 10 nglml

.LH 20 ng/ml

~ Forskolin

Figure 5 Effect of LH on the production ofcAMP by bovine myometrial tissues. Tis-sues were taken from postovulatory, luteal,and preestrous/estrous cows and incu-bated (50-mg aliquots) in the absence orpresence of LH or forskolin as a positivecontrol. Cyclic AMP was measured in tis-sue extracts after 10 minutes of incubationwith LH (5, 10, 20 ng/ml) or forskolin(10 ILmol/l). Each column represents themean :t SEM for six cows. Asterisk = sig-

nificantly different from basal levels foreach tissue, p <.05.

Postovulatory Luteal Pre-estruslestrus

PHYSIOLOGICAL SIGNIFICANCE OFCERVICAL AND MYOMETRIALLH RECEPTORSThe extragonadal actions of LH in the cow uterine tractare apparendy unrelated to the LH ovulatory peak.However, Rahe et al18 hav.e shown that there are pulsesof LH even in the luteal phase. Furthermore, the tem-poral increased expression of LH-R in the uterus maybe more significant than a rise in plasma LH.

High levels ofLH-R induced by estradiol allow arelaxing effect on the porcine myometrium, which is notseen in the absence of LH- R.19 Therefore, regulation ofLH-R resulting in increased binding ofLH and the re-sultant increase in cAMP may serve to maintain quies-cence of the uterus during the luteal phase. LH in vitro

Inositol phosphates were also induced by LH inluteal phase cervical tissues and myometrium (Fig. 6)within 10 minutes but not in preestrus/~trus or post-ovulatory phases. In contrast, oxytocin was most effec-tive in increasing inositol triphosphate during the

preestrus/estrus phase.Thus, binding ofLH to the cervical and myome-

trial LH-R is associated with signal transduction path-ways in a way similar to the accepted mechanism of ac-tion of LH in the ovary and testes, that is, activation ofthe second messenger adenylate cyclase14 and phos-phatidylinositol (PLC) pathways.15-17 Furthermore, be-cause LH also increased the expression of its own recep-tor, LH apparently acts at several sites to exert its actionon the cervix and myometrium.

Figure 6 Effect of LH (20 ng/ml) or oxy-tocin (10 ng/ml) on total tritiated inositolphosphate (Jp; IP2, IP3) in bovine myome-trium. Total inositol phosphate productionwas measured as described in Mizrachi andShemesh.B LH induced IP production within10 minutes in luteal phase myometrium butnot in preestrous/estrous or postovulatorycows. Oxytocin was effective at preestrus/estrus. Each bar represents the mean :I:SEM of six cows at each stage. Columnswith different subscripts differ significantlyfrom each other by ANOVA (P <.05).

~oc0>~0>0..

MYOMETRIAL LH RECEPTORS/SHEMESH ET AL 91

uterine vein extracts from estrus, whereas a weaker sig-

nal was seen in uterine vein extracts from the luteal

phase. However, there was no detectable signal or a

weak signal in uterine veins from the postovulatory

phase.9

INDUCTION OF CYCLOOXYGENASE BY LH

IN BOVINE UTERINE VEIN

There was a direct effect of LH on the induction of

uterine vein cyclooxygenase. Using endothelial layer

minces from uterine veins, it was shown that LH

(20 ng/mL) stimulated cyclooxygenase after 3 and

6 hours of incubation and this stimulation increased

until 15 hours, after which time the signal was less in-tense. LH induced more than a 100:!: 20% (n = 4) in-

crease in the expression of cyclooxygenase by uterine

vein from preestrous/estrous cows.

EFFECT OF LH AND MELITTIN ON

PROSTAGLANDIN PRODUCTION BY

UTERINE VEIN IN VITRO

Activation of cyclooxygenase by exogenous LH is asso-

ciated with increa~ed PCFza and PCEz production by

veins. When vascular tissues from preestrus/estrus were

incubated with LH and prostaglandins were deter-

mined, LH significantly increased PCF Za and PCEz

production. No effect of LH on PCFZa or PCEz pro-

duction was seen in the uterine artery. On the other

hand, activation of phospholipase Az by mellitin in-

creased PC F Za production by both the uterine artery

and vein (Figs. 8 and 9).

has been shown to affect the contractility of oviduct.2°The amplitude and frequency of oviductal contractiondecreased when the LH- R population was increased byestradiol. However, in the oviduct, the maximum LH -Rpopulation exists during the follicular phase and no ef-fect ofLH was seen during the luteal phase.

PROSTAGLANDIN PRODUCTION BYVASCULAR TISSUEProstaglandins are produced by vascular tissue, andthere is great regional variability in this production.6,21Lacroix and Kann22 have suggested that prostaglandinsproduced by vascular tissue could playa role in the well-documented rise in prostaglandin F 2a (PGF 2a) seen inuterine vein blood during preestrus.23 They found thatprostaglandin production by the ovine endometriumwas lower on day 16-17 (estrus) than on day 14 (lateluteal). Similarly, we found that cyclooxygenase expres-sion in bovine myometrium (Fig. 7) and endome-trium24,25 was lower during preestrus/estrus than duringthe luteal phase. This agrees with observations of Basuand Kindahl,26 who found that the prostaglandin syn-thetic capacity of the bovine uterus is much lower onthe day of estrus than on day 14 or 17.

In the uterine vein, LH-R mRNA and LH-Rprotein are expressed in preestrus/ estrus in the COW.9There was only a weak or nondetectable signal formRNA in uterine veins from luteal or postovulatoryphase cows. Similarly, there is only a weak or nonde-tectable signal for LH-R mRNA in arteries at any stageof the cycle (luteal, preestrus/estrus, or postovulatory).A strong signal for 93-kDa LH-R protein is present in

]~.6£e0,Q)

oLPostovu]atory Luteal Pre-estrusl es~

Figure 7 Effect of LH on the expression of cyclooxygenase (72 kDa) in the bovine myometrium. Myometrial tissues were takenfrom preestrus/estrus, postovulatory, and luteal phase and incubated (four 25-mg aliquots) in the absence or presence of LH(20 ng/ml) for 180 minutes. Soluble cells extracts (60 jJ.g of protein) were prepared and analyzed as described in Mizrachl andShemeshB and used for Western blot analysis in the presence of antibody for bovine cyclooxygenase. The graph shows the percent-age of stimulation over control values in every stage. Columns are means :t SE for five cows. * p <.05.

.0~~Q)~Q)

litin had any effect on PGE2 production by uterineartery under similar conditions.

These data demonstrate that (1) LH mRNA isexpressed in the bovine uterine vein and (2) LH-R pro-tein is present in the uterine vein. The receptor and itsmRNA are expressed maximally at the time of the LHpeak, that is, preestrus/estrus. The possible physiologi-cal significance of the presence ofLH-R protein is evi-dent from the observation that LH increased the ex-pression of cyclooxygenase and the production ofcyclooxygenase products by the uterine vein.

Expression ofLH-R mRNA and the presence ofLH- R protein have been reported for human uterinearteries.6,27 Furthermore, these authors reported thatexogenous hCG can increase cyclooxygenase and theformation of vasoactive eicosanoids in the human uter-ine artery as determined by immunohistochemistry.Binding of labeled hCG has also been reported in theporcine uterine vein and artery28 and in the vasculatureof the bovine corpus luteum.29 Although the concentra-tion of binding sites increased during the luteal phase inpig vasculature, no such changes in hCG/LH bindingsites could be demonstrated in bovine ovarian vessels.

Figure 8 PGF 2a production by uterine veins in the presence orabsence of progesterone (10 ng/mU. estradiol (10 ng/mU. bLH(20 ng/mU. or mellitin (20 IJg/mU. Minces (50 mg) of veinswere incubated for 3 or 6 hours in TCM 199. PGF2a was mea-sured directly in the media by radioimmunoassay (RIA). Alltreatments were conducted in quadruplets. Each group con-tained nine cows. Columns with different superscripts weresignificantly different from each other by ANOVA {P <.01 ).

TISSUE SPECIFICITY OF RESPONSETO LHSTIMULATION OF CYCLOOXYGENASEEnhancement ofboth PGF2" and PGE2 production byLH was tissue specific because it was seen only in theuterine vein and not in the uterine artery. This effectwas specific to bLH as activation of phospholipase A2by mellitin, which caused a significant increase inPGF2" in both vein and artery, did not elevate PGE2 in

On the other hand, PGE2 production by the veinpreparations was elevated (P <.05) by LH after 6 hoursof incubation but not after 3 hours (Fig. 10). There wasno demonstrable effect of mellitin on PGE2 productionafter 3 or 6 hours of incubation. Neither LH nor mel-

.Control

~Progesterore

O &trogen

m Mellitin

,-.~ 10~"~.~~ 8tr=.,..~ 6+

"t~ 4+="~~~~ 2

a a aFigure 9 PGF2a production by uterine arter-ies in the presence or absence of progester-one (10 ng!mL), estradiol (10 ng!mL), bLH(20 ng/mL), or mellitin (20 IJg!mL). Minces(50 mg) of veins were incubated for 3 or6 hours in TCM 199. PGF 2a was measured di-rectly in the media by RIA. All treatmentswere conducted in quadruplets. Each groupcontained nine cows. Columns with differentsuperscripts were significantly different fromeach other by ANOVA (P < .01) .

.Con1rol~ ProgesteroneO &trogen~LH~ MeDitin

--8-.s">".! 7

Figure 10 PGE2 production by uterine veins in the presence orabsence of progesterone (10 ng/mL), estradiol (10 ng/mL), bLH(20 ng/mL), or mellitin (20 ~g/mL). Minces (50 mg) of veinswere incubated for 3 or 6 hours in TCM 199. PGE2 was mea-sured directly in the media by RIA. All treatments were con-ducted in quadruplets. Each group contained six cows. NS =

not significant. Columns with different superscripts differed sig-nificantly from each other by ANOVA (P <.01 ).

ewe.30.31 Because LH does increase cyclooxygenase andits products in the uterine vein during preestrus/estrus,some of the prostaglandin measured in the uterine ve-nous blood at this time could well be the result ofprostanoid production in the vein itself.

An increase in eicosanoids during preestrus/es-trus could playa role in luteolysis by two mechanisms:(1) increasing blood flow in the countercurrent plexusbetween the uterine artery and ovarian vein by PGE2and (2) increasing the amount of luteolytic agent(PGF2<x) reaching the corpus luteum. Other roles foruterine venous PGE2 could be softening the cervix atestrus or initiation of the preovulatory development ofantral follicles and the increase in estradiol secretionfrom preovulatory follicles. The latter hypothesis is sug-gested by the discovery of a secondary LH peak at thetime ofluteolysis in the goat.32

Bovine uterine vein LH -R mRNA levels and thelevel of LH -R protein vary during the estrous cycle.Both the level ofLH mRNA and receptor protein con-centration reached maximum levels concomitantly atpreestrus/estrus. However, during the luteal phase,mRNA levels were essentially not detectable and the re-ceptor concentration was only minor compared withthat seen at preestrus/estrus. The maximal expression ofthe receptor and its mRNA at preestrus/estrus corre-lated with the maximal effect of exogenous LH on theinduction of cyclooxygenase and prostanoid productionby the uterine vein.

Additional investigations of these relationshipsmay prove important in understanding the mechanismsinvolved in LH-R regulation in both the bovine en-dometrium and vein. This, in turn, could lead to the de-sign of novel protocols to induce contraction of theuterus or regression of the corpus luteum.

either tissue. Similarly, in a few preparations of veiriwhere a stimulatory effect of estradiol on PGF 2cx wasdetected, PGE2 was not affected. Thus, the stimulatoryeffect of bLH on both PGF2cx and PGE2 is differentfrom the effect of other hormonal regulators of the cY-clooxygenase pathway products. This increased prosta-glandin production is presumably due to a direct effecton cyclooxygenase seen in the endometrium,24 myome-trium, and cervix.8 However, only PGF 2cx production inthe endometrium and only PGE2 in the cervix werestimulated by LH, whereas both PGF 2cx and PGE2 werestimulated by LH in the uterine vein.

Tissue-specific responses to stimulators of cy-clooxygenase are not limited to LH. The principalprostanoid stimulated by oxytocin in the endometriumis PGF 2cx' and in the cervix, the principal product pro-duced by oxytocin is PGE2.8,24,25

PHYSIOLOGICAL SIGNIFICANCE OF LHSTIMULATION OF UTERINE VEINPROSTANOIDS INTHE COWAt the time of preestrus/estrus, the level of cyclooxyge-nase in endometrium is very low.24 However, during ru-minant preestrus/estrus, the concentration ofPGF2IX inthe uterine venous blood is substantial, being about1-3 ng/mL in the COw23 and about 6-7 ng/mL in the

EXTRAGONADALFSHRECEPTORSIn addition to the presence of LH-R in the cervix, itwas demonstrated by both polymerase chain reactionamplification and Northern blot analysis that follicle-stimulating hormone (FSH) receptor mRNA is presentin the bovine cervix. The band corresponding to the re-ceptor protein (75 kDa) and its mRNA were maximallyexpressed during the preestrus/estrus phase. Incubationof cervical tissues with FSH increased the expression ofcyclooxygenase and production of PGE2 (and possiblyPGEJ at preestrus/estrus. Stimulation of cervical CY-clooxygenase is secondary to activation of both PLCand adenylate cyclase second messenger G protein-related pathways.

Northern blot analysis of bovine cervical tissuesfrom preestrous/estrous cows revealed multiple tran-scripts for bovine cervical FSH receptor. The sizes ofmajor transcripts were 2.5, 3.3, and 3.8 kb, which weresimilar to those obtained in bovine granulosa cells,33 rat

during estrus are lower than during the luteal phase49,5oand elevations of both peripheral oxytocin and cervicaloxytocin receptor concentrations are necessary for oxy-tocin to cause cervical softening toward parturition.40Furthermore, progesterone in vitro induced a dose-dependent inhibition ofPCE2 release by cervical tissuesfrom preestrous/ estrous cows, and this was associatedwith a decrease in both basal and oxytocin-stimulatedPCE2 production,48 It would, therefore, seem that hor-mones other than oxytocin are responsible for the in-crease in cervical PCE2 in the preestrous/estrous cow. Itcould well be that FSH, which has its peak peripheralconcentration at the time of estrus, is the hormone thatincreases cervical PCE2 because FSH receptor expres-sion is maximal at this time and FSH in vitro increasesPC E2 production by the cervix.

REFERENCES

1. Reshef E, Lei ZM, Rao CY, Pridham DD, Chegini N,Luborsky JL. The presence of gonadotropin receptors in non-pregnant human uterus, human placenta, fetal membranes,and decidua. J Clin Endocrinol Metab 1990;70:421-430

2. Bonnamy PJ, Be~haim A,-Leymarie P. Estrous cycle relatedchange of high affinity luteinizing hormone/human chorionicgonadotropin binding sites in the rat uterus. Endocrinology

1990;126:1264-12693. Jensen JD, Odell WD. Identification of LH/hCG receptors

in rabbit uterus. Proc Soc Exp BioI Med 1988;189:28-304. ZiecikAJ, Stanchev PD, TiltonJE. Evidence for the presence

of luteinizing hormone/human chorionic gonadotropin-binding sites in the porcine uterus. Endocrinology 1986;119:1159-1163

5. Ziecik AJ, Jedlinska M, Rzucidlo JS. Effect of estradiol andprogesterone on myometrial LH/hCG receptors in pigs. Acta

EndocrinoI1992;127:185-1886. Lei ZM, Reshef E, Rao CY. Novel co-expression of human

chorionic gonadotropin (hCG)/human luteinizing hormonereceptors and their ligand, hCG, in human fallopian tubes.J Clin Endocrinol Metab 1992;75:651-659

7. Salamonsen LA, Findlay JK. Regulation of endometrial pros-taglandin during the menstrual cycle and early pregnancy. Re-prod Fertil Dev 1990;2:311-319

8. Mizrachi D, Shemesh M. Expression of functionalluteinisinghormone receptor and its messenger ribonucleic acid inbovine cervix: luteinising hormone augmentation of intracel-lular cAMP, phosphate inositol and cyclooxygenase. Mol Cell

EndocrinoI1999;157:191-2009. Shemesh M, Gurevich M, Mizrachi D, et al. Expression of

functional luteinizing hormone receptor and its mRNA inbovine uterine veins; luteinizing hormone induction ofPGHS and augmentation of prostaglandin production inbovine uterine veins. Endocrinology 1997;138:4844-4851

10. Rosemblit N, Ascoli M, Segaloff DL. Characterization of anantiserum to the rat luteal luteinizing hormone/chorionic go-

nadotropin receptor. Endocrinology 1998;123:2284-229011. Rodriguez MC, Segaloff DL. The orientation of the

lutropin/choriogonadotropin receptor in rat luteal cells as re-vealed by site-specific antibodies. Endocrinology 1990;127:674-681

testis and ovary,34,35 and human ovary36 and myome-trium37 as well as in ovine testes,38

The nucleotide sequence homology betweenFSH -R mRNA found in the cervix and ovarianbFSH -R was 97.3%. Using specific antibody raised inrabbits against hFSH (amino acid sequence 265-296)in Western blot analysis resulted in a major signal for75-kDa protein. A protein of similar molecular size hasbeen reported in rat and human ovary.39 A strong signalfor this protein was seen in the preestrous/ estrous cervixcompared with other stages of the cycle. This cervicalreceptor was regulated by FSH itself, similar to regula-tion of the FSH receptor in the rat ovary.35

FSH increased cAMP production by cervical tis-sue from the preestrus/estrus phase but did not elevatecAMP in postovulatory and luteal phase. FSH elevationof inositol phosphates displayed the same pattern. Itwould, therefore, appear that the cervical FSH receptoris associated with signal transduction pathways in a waysimilar to the accepted mechanism ofFSH action in theovary and testes, that is, activation of the second mes-senger pathways adenylate cyclase14 and phosphatidyl-inositol cycle (PLC).15,16 An inhibitory effect of FSHon inositol phosphates and cAMP at postovulation oc-curs when FSH receptor is low.

FSH induced about a 200% increase in the ex-pression of cervical cyclooxygenase of preestrus/estrus:This was similar to the response of cyclooxygenase toLH that was observed for bovine endometrium24,25 andthe uterine vein.9 However, in the endometrium, LHincreased cyclooxygenase during both the luteal andpostovulatory phases but not at estrus.24,25 Furthermore,induction of cyclooxygenase by gonadotropin in the en-dometrium was associated with an increased level ofPGF2a' whereas in the cervix PGE2 was the major

product.Relaxation and opening of the gravid cervix are

due to active biochemical and structural changes in cer-vical connective tissues that are, in part, mediated byprostaglandins.40 These events are related to stretchingof the cervix, which causes the release of prosta-glandins.41,42 The effect of PGE2 in causing cervicalsoftening in the ewe is also well documented.43-45 Inboth nonpregnant and pregnant cows, PGE2 causes anincrease in cervical opening within 3 hours of treat-ment.46 PGE1, administered intracervically in a jelly,was shown to decrease cervical resistance within24 hours.47

Oxytocin caused a significant stimulation ofPC E2 production in vitro in cervical tissues from pre-estrous/estrous cows but had no effect on PGE2 pro-duction in cervical tissue from other stages of the cowestrous cycle.48 Similarly, in an initial report,47 it wasshown that administration of oxytocin to preestrouscow increased the PCE2 concentration in the cervicalexudate. However, peripheral oxytocin concentrations

and in ovarian and luteal tissue of pregnant and nonpregnantewes.] Anim Sci 1975;41:154-159

31. Lewis GS, Wilson ]R, Wilks ]W, et al. PGF2a and itsmetabolites in uterine and jugular venous plasma and en-dometrium of ewes during early pregnancy. ] Anim Sci

1977;45:320-32732. Mori Y, Kano Y. Changes in plasma concentrations of LH,

progesterone and oestradiol in relation to the occurrence ofluteolysis, oestrus and the time of ovulation in the Shiba goat

(Capra hircus}.] Reprod FertiI1984;72:223-23033. Houde A, Lambert A, Saumande ], Silversides DW, Lussier

]G. Structure of bovine follicle-stimulating hormone receptorcomplementary DNA and expression in bovine tissues. MolReprod Dev 1994;39:127-135

34. Heckert LL, Griswold MD. Expression of follicle-stimulating hormone receptor mRNA in rat testes and sertolicells. Mol EndocrinoI1991;5:67Q-{)77

35. LaPolt PS, Tilly ]L, Aihara T, Nishimori K, Hsueh A]W.Gonadotropin-induced up-and-down regulation of rat ovar-ian LH receptor message levels during growth, ovulation andluteinization. Endocrinology 1992;130:1289-1295

36. Tilly ]L, Aihara T, Nishimori K, et al. Hormonal regulationof follicle-stimulating hormone receptor messenger ribonu-cleic acid levels in cultured granulosa cells. Endocrinology

1992;1131:799-80637. Kornyei ]L, Li X, Lei ZM, Rao CV. Restoration of human

chorionic gonadotropin response in human myometrialsmooth muscle cells by treatment with follicle-stimulatinghormone (FSH): ~vidence for the presence ofFSH receptorsin human myometrium. Eur] EndocrinoI1996;134:225-231

38. Khan H, Yarney TA, Sairam MR. Cloning of alternatelyspliced mRNA transcripts coding for variants of ovine testic-ular follitropin receptor lacking the G protein coupling do-'mains. Biochem Biophys Res Commun 1993;190:888-894

39. Liu X, DePasquale, ]A, Griswold MD, Dias ]A. Accessibilityof rat and human follitropin receptor primary sequence(R265-S296) in situ. Endocrinology 1994;135:682-691

40. Fuchs A-R, Goeschen], Rasmussen AB, RehnstromJV. Cer-vical ripening by endocervical and extra-amniotic PGE2.

Prostaglandins 1984;28:217-22741. Ellwood DA, Mitchell MD, Anderson ABM, Turnbull AC.

Specific changes in the in vitro production of prostanoids bythe ovine cervix at parturition. Prostaglandins 1980;39:675-684

42. Hiller K, Coad N. Synthesis of prostaglandins by the humanuterine cervix in vitro during passive mechanical stretch.] Pharm PharmacoI1982;34:262-263

43. Stys S], Dresser BL, Ott TE, Clark KE. Effects of prosta-glandin E2 on cervical compliance in pregnant ewes. Am ]Obstet GynecoI1981;140:415-419

44. Ledger WL, Ellwood, DA, Taylor M]. Cervical softening inlate pregnant sheep by infusion of prostaglandin E2 into cer-vical artery.] Reprod FertiI1983;69:511-515

45. Khalifa RME, Sayre BL, Lewis GS. Exogenous oxytocin di-lates the cervix in the ewes. ] Anim Sci 1992;70:38-42

46. Duchens M, Fredriksson G, KindaW ~, Aiumlamai S. Effectof intracervical administration of a prostaglandin E2 gel inpregnant and non-pregnant heifers. Vet Rec 1993;133:546-549

47. Grady L, Fields M, Kowalski A, Chang S-M, Fuchs A-R.Effects of oxytocin and PGEl on bovine cervix at estrus. BioI

Reprod 1998;58(suppl)1:174(abstract 327)48. Shemesh M, Dombrovski L, Gurevich M, et al. Regulation of

bovine cervical secretion of prostaglandins and synthesis of

50. Ohtani M, Kobayashi S-I, Miyamoto A, Hayashi K,Yutaka F. Real-time relationships between intraluteal andplasma concentrations of endothelin, oxytocin and progester-one during prostaglandin F 2« -induced luteolysis in the cow.Biol Reprod 1998;58:103-108

cyclooxygenase by oxytocin. Reprod Fertil Dev 1997;9:525-530

49. Schams D. Oxytocin determination by radioimmunoassay:III. improvement to subpicogram sensitivity and applicationto blood levels in cyclic cattle. Acta Endocrinol 1983;103:180-183

Functional importance of bovine myometrial and vascular LH receptors and cervical FSH receptors

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