scholarly journals Actions of gonadotrophins on the uterus

Reproduction ◽  
2001 ◽  
pp. 835-842 ◽  
Author(s):  
M Shemesh
Keyword(s):  
Binding Sites ◽  
Luteal Phase ◽  
Physiological Role ◽  
Oestrous Cycle ◽  
Receptor Protein ◽  
Fsh Receptor ◽  
Lh Receptor ◽  
Receptor Mrna ◽  
Maximum Expression ◽  
Peak Value

Binding sites for LH/hCG are found in the uterus of several species, including humans. In cattle and pigs, the LH receptor, its mRNA and LH receptor protein are present in the uterus throughout the oestrous cycle, and maximum expression occurs at the luteal phase. GnRH receptor is also expressed maximally in the human endometrium at the luteal phase. LH activates both the adenylate cyclase and phospholipase C pathways and increases the concentrations of cyclooxygenase and its products. Activation of LH receptors in the endometrium is associated with PGF production. In contrast, bovine uterine vein LH receptor mRNA and LH receptor concentrations are greatest during pro-oestrus-oestrus and LH increases the production of both PGE and PGF. FSH receptor and its mRNA are present in the bovine cervix and the concentrations are greatest at the time of the FSH peak value in the blood, indicating a physiological role for FSH in the relaxation and opening of the cervix. The presence of gonadotrophin and releasing factor receptors with a dynamic pattern in the endometrium, myometrium, oviduct and cervix of different species provides evidence that gonadotrophins and GnRH play a substantial role as molecular autocrine-paracrine regulators of the oestrous cycle and implantation.

scholarly journals Increased ovulation rate in gilts treated with dihydrotestosterone

Reproduction ◽  
2002 ◽  
pp. 527-533 ◽  
Author(s):  
H Cardenas ◽  
WF Pope ◽  
Keyword(s):  
Body Weight ◽  
Androgen Receptor ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Fsh Receptor ◽  
Receptor Mrna ◽  
Preovulatory Follicles ◽  
Early Follicular Phase

Treatment with testosterone increases ovulation rate in pigs. The present study was conducted to examine the effects of 5alpha-dihydrotestosterone (DHT), a non-aromatizable androgen receptor ligand, on ovulation rate and amounts of androgen receptor and FSH receptor mRNAs in postpubertal gilts. In Expt 1, ovulation rate in response to daily i.m. injections of 0, 6, 60 or 600 microg DHT kg(-1) body weight from day 13 of the oestrous cycle (day 0 = day 1 of oestrus) to the following oestrus increased with each dose of DHT (P < 0.05). The mean increase in number of corpora lutea ranged from approximately three to 17 over the three dosages of DHT. In Expt 2, gilts treated daily with 60 microg DHT kg(-1) body weight during the early follicular phase (from day 13 to day 16), coincident with follicular recruitment, or the late follicular phase (day 17 to oestrus), had higher (P < 0.05) rates of ovulation compared with gilts that received vehicle, and were not different from gilts treated with DHT from day 13 to oestrus. Percentage recovery of day 3 embryos was not altered when gilts were treated from day 13 to day 16 or from day 17 to oestrus; however, treatment of gilts with DHT from day 13 to oestrus decreased recovery of day 3 (Expt 1) or day 11 (Expt 2) conceptuses. Daily administration of 6 microg DHT kg(-1) body weight to gilts from day 13 of the oestrous cycle to the following oestrus (Expt 3) did not affect the relative amounts of androgen receptor mRNA, but increased (P < 0.05) the amounts of FSH receptor mRNA in preovulatory follicles as determined by RT-PCR. The results of these experiments indicate that androgens may regulate ovulation rate in gilts. One of the roles of androgens might be regulation of the amounts of FSH receptor mRNA in ovarian follicles.

Oxytocin receptors in the oviduct during the oestrous cycle of the ewe

1990 ◽  
Vol 124 (3) ◽  
pp. 353-359 ◽  
Author(s):  
V. J. Ayad ◽  
S. A. McGoff ◽  
D. C. Wathes
Keyword(s):  
Binding Sites ◽  
Luteal Phase ◽  
Dissociation Constants ◽  
Relative Concentration ◽  
Oestrous Cycle ◽  
Affinity Binding ◽  
High Affinity Binding ◽  
Lower Affinity ◽  
High Affinity ◽  
Oxytocin Receptors

ABSTRACT The presence of oxytocin receptors in ovine oviduct has been investigated. High-affinity binding sites for [3H]oxytocin were detected in crude membrane fractions prepared from the oviducts of ewes killed during the oestrous period. The dissociation constant calculated for these sites in competition studies was 1·7 nmol/l. Similar dissociation constants were calculated for [Arg8]-vasopressin and the oxytocin-specific agonists [Gly7]-oxytocin and [Thr4, Gly7]-oxytocin, indicating that these sites represent oxytocin receptors. At least one additional site of lower affinity and undetermined identity was present. The relative concentration of oxytocin-binding sites in preparations of oviduct membranes were estimated in ewes killed at different stages of the oestrous cycle using a single concentration of [3H]oxytocin. Binding was low during the luteal phase of the cycle but increased to a maximum at oestrus (77·7 fmol/mg protein). Binding fell after ovulation, reaching what appeared to be basal concentrations by the early luteal stage of the cycle. Binding to oviductal membranes from prepubertal, anoestrous and pregnant ewes was also low, but in anoestrous animals which had been treated with progesterone and oestrogen it was similar to values measured in ewes at oestrus. These results are consistent with the existence of oviductal oxytocin receptors which are regulated by ovarian steroids. We conclude that oxytocin receptors are present in the oviduct of the ewe around the time of ovulation. The significance of oxytocin to events taking place in the oviduct at this time remains to be determined. Journal of Endocrinology (1990) 124, 353–359

Insulin-like growth factor I receptor mRNA and protein expression in pig corpora lutea

Reproduction ◽  
2000 ◽  
pp. 109-114 ◽  
Author(s):  
Z Ge ◽  
WE Nicholson ◽  
DM Plotner ◽  
CE Farin ◽  
JE Gadsby
Keyword(s):  
Growth Factor ◽  
Corpus Luteum ◽  
Oestrous Cycle ◽  
Receptor Protein ◽  
Corpora Lutea ◽  
Western Blots ◽  
Luteal Cells ◽  
Factor I ◽  
Receptor Mrna ◽  
Igf I

Insulin-like growth factor I (IGF-I) is believed to play a luteotrophic role in the pig corpus luteum during the oestrous cycle. Since the actions of IGF-I in target tissues are mediated by the type I IGF receptor, the concentrations of IGF-I receptor mRNA and protein were examined in pig corpora lutea at different stages of the oestrous cycle. Corpora lutea were collected from normally cyclic gilts on days 4, 7, 10, 13, 15 and 16 of the oestrous cycle (n = 4 animals per day). Corpora lutea on days 7, 10 and 13 were dissociated with collagenase, and large and small luteal cell sub-populations were separated by elutriation. Northern and slot blots were used to examine mRNA, and western blots were used to measure the concentrations of IGF-I receptor protein in the pig corpus luteum. On northern blots, luteal IGF-I receptor mRNA was present as a single 11 kb transcript. The slot blots showed that the steady state expression of IGF-I receptor mRNA increased significantly (P < 0.05) from its lowest value on day 4, to reach a maximum on days 13-16. IGF-I receptor mRNA was also expressed to a greater extent in large compared with small luteal cells (P < 0.05). On western blots, IGF-I receptor appeared as a 95 kDa protein band (beta-subunit) and IGF-I receptor protein concentrations were significantly higher (P < 0.05) on days 4-10 than on days 13-16. Finally, large luteal cells appeared to contain more IGF-I receptor protein than the small luteal cells. In conclusion, since IGF-I receptor was detected in the pig corpus luteum, it is a likely target tissue for IGF-I, especially during the early luteal phase. Furthermore, IGF-I receptor was localized primarily on large luteal cells, thus it is hypothesized that IGF-I may play a paracrine role in the pig corpus luteum.

Characterization and localization of a putative oxytocin receptor in the cervix of the oestrous ewe

1994 ◽  
Vol 142 (3) ◽  
pp. 397-405 ◽  
Author(s):  
E L Matthews ◽  
V J Ayad
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Luteal Phase ◽  
Specific Binding ◽  
Oxytocin Receptor ◽  
Oestrous Cycle ◽  
Secretory Cells ◽  
Cervical Tissue ◽  
High Affinity ◽  
General Decline

Abstract The purpose of the present study was to investigate the presence of high-affinity oxytocin-binding sites (putative oxytocin receptors) in the cervix of the non-pregnant ewe. [3H]Oxytocin binding to the peripheral layers of cervical tissue (comprising the serosal layer and the least dense collagenous and muscular layers) and the remaining dense collagenous cervical tissue were studied separately. [3H] Oxytocin-binding sites were detected in membrane fractions prepared from both of these regions, but binding to the peripheral cervix was variable and binding site concentrations were low, hence these were not characterized further. A high-affinity oxytocin-binding site, having a dissociation constant of 1·8 nmol/l, was characterized in the dense collagenous regions of the cervix of ewes killed during the oestrous period. Similar dissociation constants were determined for [Arg8]-vasopressin and the oxytocin-specific agonist [Thr4, Gly7]-oxytocin in competition studies. [3H] Oxytocin binding to peripheral cervical tissue and to the dense collagenous cervix was generally low or undetectable during the luteal phase, but increased in both tissues around the time of luteolysis. Although specific binding to both tissues was variable during the oestrous period, it was higher at this time than during the luteal phase. [3H] Oxytocin-binding site concentrations were also found to be higher within the inner dense collagenous cervix of oestrous ewes than of pregnant, ovariectomized or anoestrous animals. During the oestrous cycle, oxytocin-binding site concentrations reached a maximum in the dense collagenous cervical tissue on the day of oestrus (141·8 ±44 (s.e.m.) fmol/mg protein), showing a general decline during the following days back to luteal phase values. This compared with concentrations of 513·3 ±132·1 and 216·1 ± 13·9 fmol/mg protein, measured for comparative purposes in endometrial and myometrial membrane preparations, respectively, on the day of oestrus in the same group of ewes. However, in membrane preparations of peripheral cervical tissue higher concentrations were measured on day 14 than on the following 2 days and maximal concentrations were not reached until the day after oestrus (52·7 ± 4·2 fmol/mg protein). Concentrations were maintained at similar values during the subsequent 2 days and significant specific binding was still measurable in both regions of the cervix on day 5. The localization of oxytocin-binding sites within dense collagenous cervical tissue was investigated autoradiographically using the 125I-labelled specific oxytocin receptor antagonist [1(β-mercapto-β,β-cyclopentamethylene propionic acid), 2-(ortho-methyl)-Tyr2, Thr4, Orn8, Tyr9 -NH2]-vasotocin. The only clear specific labelling was localized to the luminal epithelium of the uterine section of the cervix of oestrous ewes, with labelling in ewes in the luteal phase clearly reduced or absent. The results demonstrate the presence of a high-affinity oxytocin-binding site within the cervix of the oestrous ewe which is associated with secretory cells and which undergoes similar changes in concentration during the oestrous cycle to uterine oxytocin receptor sites. The significance of this novel putative site of oxytocin action remains to be established. Journal of Endocrinology (1994) 142, 397–405

scholarly journals Immunization of Male Bonnet Monkeys (M. radiata) with a Recombinant FSH Receptor Preparation Affects Testicular Function and Fertility

Endocrinology ◽  
1997 ◽  
Vol 138 (7) ◽  
pp. 3065-3068 ◽  
Author(s):  
N. R. Moudgal ◽  
M. R. Sairam ◽  
H. N. Krishnamurthy ◽  
Surekha Sridhar ◽  
H. Krishnamurthy ◽  
...  
Keyword(s):  
Receptor Protein ◽  
Fsh Receptor ◽  
Recombinant Fsh ◽  
Protein Preparation ◽  
Lh Receptor ◽  
Fertility Index ◽  
Contraceptive Vaccine ◽  
A Value ◽  
Sperm Counts ◽  
Blocking Antibodies

Abstract Immunization of proven fertile adult male monkeys (n = 3) with a recombinant FSH receptor protein preparation (oFSHR-P) (representing amino acids 1–134 of the extracellular domain of the receptor Mr∼ 15KDa) resulted in production of receptor blocking antibodies. The ability of the antibody to bind a particulate FSH receptor preparation and receptors in intact granulosa cells was markedly (by 30–80%) inhibited by FSH. Serum T levels and LH receptor function following immunization remained unchanged. The immunized monkeys showed a 50% reduction (p&lt; 0.001) in transformation of spermatogonia (2C) to primary spermatocytes (4C) as determined by flow cytometry and the 4C:2C ratio showed a correlative change (R 0.81, p&lt; 0.0007) with reduction in fertility index (sperm counts X motility score). Breeding studies indicated that monkeys became infertile between 242–368 days of immunization when the fertility index was in the range of 123 ± 76 to 354 ± 42 (compared to a value of 1602 ± 384 on day 0). As the effects observed are near identical to that seen following immunization with FSH it is suggestive that oFSHR-P can substitute for FSH in the development of a contraceptive vaccine.

Studies of the oestrous cycle, oestrus and pregnancy in the koala (Phascolarctos cinereus)

Reproduction ◽  
2000 ◽  
pp. 49-57 ◽  
Author(s):  
SD Johnston ◽  
MR McGowan ◽  
P O'Callaghan ◽  
R Cox ◽  
V Nicolson
Keyword(s):  
Luteal Phase ◽  
Post Partum ◽  
Plasma Concentrations ◽  
External Genitalia ◽  
Oestrous Cycle ◽  
Phascolarctos Cinereus ◽  
Pregnant Females ◽  
Peripheral Plasma ◽  
The Mean ◽  
High Concentrations

As an integral part of the development of an artificial insemination programme in the captive koala, female reproductive physiology and behaviour were studied. The oestrous cycle in non-mated and mated koalas was characterized by means of behavioural oestrus, morphology of external genitalia and changes in the peripheral plasma concentrations of oestradiol and progestogen. The mean (+/- SEM) duration of the non-mated oestrous cycle and duration of oestrus in 12 koalas was 32.9 +/- 1.1 (n = 22) and 10.3 +/- 0.9 (n = 24) days, respectively. Although the commencement of oestrous behaviour was associated with increasing or high concentrations of oestradiol, there were no consistent changes in the morphology or appearance of the clitoris, pericloacal region, pouch or mammary teats that could be used to characterize the non-mated cycle. As progestogen concentrations remained at basal values throughout the interoestrous period, non-mated cycles were considered non-luteal and presumed anovulatory. After mating of the 12 koalas, six females gave birth with a mean (+/- SEM) gestation of 34.8 +/- 0.3 days, whereas the remaining six non-parturient females returned to oestrus 49.5 +/- 1. 0 days later. After mating, oestrous behaviour ceased and the progestogen profile showed a significant increase in both pregnant and non-parturient females, indicating that a luteal phase had been induced by the physical act of mating. Progestogen concentrations throughout the luteal phase of the pregnant females were significantly higher than those of non-parturient females. Parturition was associated with a decreasing concentration of progestogen, which was increased above that of basal concentrations until 7 days post partum.

scholarly journals Heterodimerization Between the Lutropin and Follitropin Receptors is Associated With an Attenuation of Hormone-Dependent Signaling

Endocrinology ◽  
2013 ◽  
Vol 154 (10) ◽  
pp. 3925-3930 ◽  
Author(s):  
Xiuyan Feng ◽  
Meilin Zhang ◽  
Rongbin Guan ◽  
Deborah L. Segaloff
Keyword(s):  
Protein Interactions ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
G Protein Coupled Receptors ◽  
Fsh Receptor ◽  
Bioluminescence Resonance Energy Transfer ◽  
Protein Protein Interactions ◽  
Lh Receptor ◽  
G Protein Coupled ◽  
Stimulation Of

The LH receptor (LHR) and FSH receptor (FSHR) are each G protein-coupled receptors that play critical roles in reproductive endocrinology. Each of these receptors has previously been shown to self-associate into homodimers and oligomers shortly after their biosynthesis. As shown herein using bioluminescence resonance energy transfer to detect protein-protein interactions, our data show that the LHR and FSHR, when coexpressed in the same cells, specifically heterodimerize with each other. Further experiments confirm that at least a portion of the cellular LHR/FSHR heterodimers are present on the cell surface and are functional. We then sought to ascertain what effects, if any, heterodimerization between the LHR and FSHR might have on signaling. It was observed that when the LHR was expressed under conditions promoting the heterodimerization with FSHR, LH or human chorionic gonadotropin (hCG) stimulation of Gs was attenuated. Conversely, when the FSHR was expressed under conditions promoting heterodimerization with the LHR, FSH-stimulated Gs activation was attenuated. These results demonstrate that the coexpression of the LHR and FSHR enables heterodimerizaton between the 2 gonadotropin receptors and results in an attenuation of signaling through each receptor.

Seasonal and steroid-dependent effects on the modulation of LH secretion in the ewe by intracerebroventricularly administered β-endorphin or naloxone

1989 ◽  
Vol 122 (2) ◽  
pp. 509-517 ◽  
Author(s):  
R. J. E. Horton ◽  
H. Francis ◽  
I. J. Clarke
Keyword(s):  
Breeding Season ◽  
Luteal Phase ◽  
Pulse Frequency ◽  
Opioid Peptide ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Opioid Antagonist ◽  
Endogenous Opioid ◽  
Endogenous Opioid Peptide ◽  
Lh Secretion

ABSTRACT The natural opioid ligand, β-endorphin, and the opioid antagonist, naloxone, were administered intracerebroventricularly (i.c.v.) to evaluate effects on LH secretion in ovariectomized ewes and in ovariectomized ewes treated with oestradiol-17β plus progesterone either during the breeding season or the anoestrous season. Ovary-intact ewes were also studied during the follicular phase of the oestrous cycle. Jugular blood samples were taken at 10-min intervals for 8 h and either saline (20–50 μl), 100 μg naloxone or 10 μg β-endorphin were injected i.c.v. after 4 h. In addition, luteal phase ewes were injected i.c.v. with 25 μg β-endorphin(1–27), a purported endogenous opioid antagonist. In ovariectomized ewes, irrespective of season, saline and naloxone did not affect LH secretion, but β-endorphin decreased the plasma LH concentrations, by reducing LH pulse frequency. The effect of β-endorphin was blocked by administering naloxone 30 min beforehand. Treating ovariectomized ewes with oestradiol-17β plus progesterone during the breeding season reduced plasma LH concentrations from 6–8 μg/l to less than 1 μg/l. In these ewes, saline did not alter LH secretion, but naloxone increased LH pulse frequency and the plasma concentrations of LH within 15–20 min. During anoestrus, the combination of oestradiol-17β plus progesterone to ovariectomized ewes reduced the plasma LH concentrations from 3–5 μg/l to undetectable levels, and neither saline nor naloxone affected LH secretion. During the follicular phase of the oestrous cycle, naloxone enhanced LH pulse frequency, which resulted in increased plasma LH concentrations; saline had no effect. In these sheep, β-endorphin decreased LH pulse frequency and the mean concentrations of LH, and this effect was prevented by the previous administration of naloxone. The i.c.v. administration of β-endorphin(1–27) to luteal phase ewes did not affect LH secretion. These data demonstrate the ability of a naturally occurring opioid peptide to inhibit LH secretion in ewes during the breeding and non-breeding seasons, irrespective of the gonadal steroid background. In contrast, whilst the gonadal steroids suppress LH secretion in ovariectomized ewes during both seasons, they only appear to activate endogenous opioid peptide (EOP)-mediated inhibition of LH secretion during the breeding season. Furthermore, these data support the notion that LH secretion in ovariectomized ewes is not normally under the control of EOP, so that naloxone has no effect. Journal of Endocrinology (1989) 122, 509–517

Passively immunizing ewes against inhibin during the luteal phase of the oestrous cycle raises the plasma concentration of FSH

1989 ◽  
Vol 123 (3) ◽  
pp. 383-391 ◽  
Author(s):  
G. E. Mann ◽  
B. K. Campbell ◽  
A. S. McNeilly ◽  
D. T. Baird
Keyword(s):  
Plasma Concentration ◽  
Luteal Phase ◽  
Passive Immunization ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
Control Group ◽  
Pituitary Cells ◽  
Marked Rise ◽  
Peripheral Plasma

ABSTRACT Passive immunization was used to investigate the importance of inhibin in the negative feedback loop regulating the production of FSH in sheep. An antiserum raised to the 1–26 peptide fragment of the N-terminus of the α-chain of porcine inhibin was first shown to neutralize the suppressive effects of inhibin on the production of FSH by dispersed ovine pituitary cells in vitro. Groups of five mature Scottish Blackface ewes on day 8 of the luteal phase of the oestrous cycle were then injected with either 10 ml plasma from normal ewes (control) or 10 ml ovine inhibin antiserum. On day 10, luteal regression was induced by an i.m. injection of cloprostenol (100 μg), and ovulation rate determined 6 days later by laparoscopy. Peripheral plasma samples were collected throughout the experimental period. Following treatment, there was no change in the peripheral plasma concentration of LH in either group. Following injection of the inhibin antiserum, the concentration of FSH rose significantly (P<0·001) compared with the control group. The concentration of FSH rose from 1·42 ± 0·06 to a maximum of 2·58 ± 0·23 (s.e.m.) μg/l by 5·6 ±0·9 h, this maximum lasting 9·0±1·1 h. By 32·8 ±6·9 h, the concentration of FSH had returned to pretreatment levels, while the titre of free antibody in the plasma of treated ewes was still high. In the treated ewes, there were one single and four double ovulations compared with three single and two double ovulations in the control group, indicating that the inhibin immunization may have resulted in an increase in ovulation rate. We conclude that the marked rise in the plasma concentration of FSH following injection of inhibin antiserum provides strong evidence that inhibin is an important factor in the regulation of FSH production by the pituitary gland at this time. Journal of Endocrinology (1989) 123, 383–391

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