Induced Ovulation in Albino Rats Exposed to Constant Light

Brown-Grant, K.; Davidson, Julian M.; Greig, Fenella

doi:10.1677/joe.0.0570007

Cited by 100 publications

(64 citation statements)

References 28 publications

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“…They display persistent vaginal oestrus and ovulate in response to copulation (Brown-Grant et al 1973).…”

Section: Pituitary and Gonadal Activationmentioning

confidence: 99%

Neural transplantation in hypogonadal (hpg) mice – physiology and neurobiology

Charlton¹

2004

Reproduction

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The hypogonadal (hpg) mouse mutant has a deletion in the region encoding the hypothalamic gonadotrophic hormone-releasing hormone decapeptide. As a consequence pituitary gonadotrophic hormone synthesis and release is severely curtailed and there is little or no post-natal gonadal development. Grafts of late fetal/early neonatal brain tissue containing the decapeptide-producing neurones into the third ventricle of hpg mice result, in a majority of animals, in a near normalisation of pituitary function with full spermatogenesis in male mice and full follicular and uterine development in females. The vast majority of positive responding females with vaginal opening and uterus growth show no evidence of spontaneous oestrous cycles, ovulation or corpora lutea. These female mice mate with normal males with many of them demonstrating reflex ovulation. In both male and female mutants with successful grafts there is an absence of gonadal steroid negative feedback upon the synthesis and secretion of pituitary gonadotrophic hormones. The releasing factor axon terminals from grafts within the third ventricle identified by immunohistochemical methods are targeted specifically to the median eminence. There is evidence for host innervation of grafts, but how specific this is for the control of gonadotrophic hormone-releasing hormone cell bodies remains to be elucidated.

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“…They display persistent vaginal oestrus and ovulate in response to copulation (Brown-Grant et al 1973).…”

Section: Pituitary and Gonadal Activationmentioning

confidence: 99%

Neural transplantation in hypogonadal (hpg) mice – physiology and neurobiology

Charlton¹

2004

Reproduction

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“…The reflex ovulator lacks behavioral and ovarian estrous cycles. Interestingly, spontaneous ovulators may have an inherent mechanism mediating mating-induced ovulation, because rats are known to show reflex ovulation when maintained in a constant-light condition (2,3). It has been suggested that coitus-induced ovulation even occurs in women (4).…”

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confidence: 99%

Kisspeptin neurons mediate reflex ovulation in the musk shrew ( Suncus murinus )

Inoue

Sasagawa

Ikai

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The present study investigated whether kisspeptin-G protein-coupled receptor 54 (GPR54) signaling plays a role in mediating mating-induced ovulation in the musk shrew (Suncus murinus), a reflex ovulator. For this purpose, we cloned suncus Kiss1 and Gpr54 cDNA from the hypothalamus and found that suncus kisspeptin (sKp) consists of 29 amino acid residues (sKp-29). Injection of exogenous sKp-29 mimicked the mating stimulus to induce follicular maturation and ovulation. Administration of several kisspeptins and GPR54 agonists also induced presumed ovulation in a dose-dependent manner, and Gpr54 mRNA was distributed in the hypothalamus, showing that kisspeptins induce ovulation through binding to GPR54. The sKp-29-induced ovulation was blocked completely by pretreatment with a gonadotropin-releasing hormone (GnRH) antagonist, suggesting that kisspeptin activates GnRH neurons to induce ovulation in the musk shrew. In addition, in situ hybridization revealed that Kiss1-expressing cells are located in the medial preoptic area (POA) and arcuate nucleus in the musk shrew hypothalamus. The number of Kiss1-expressing cells in the POA or arcuate nucleus was up-regulated or downregulated by estradiol, suggesting that kisspeptin neurons in these regions were the targets of the estrogen feedback action. Finally, mating stimulus largely induced c-Fos expression in Kiss1-positive cells in the POA, indicating that the mating stimulus activates POA kisspeptin neurons to induce ovulation. Taken together, these results indicate that kisspeptin-GPR54 signaling plays a role in the induction of ovulation in the musk shrew, a reflex ovulator, as it does in spontaneous ovulators.brain | copulation | Kiss1r | metastin | ovary

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“…The absence of an LH surge is presum ably the explanation for the fact that ovulation did not oc cur in the 5 animals of the non-cannulated group. The fact that the quota of ova in LL animals that ovulated was simi lar to that in animals exposed to LD contrasts with the find ings [4,10] that after long-term exposure to LL the ovulato ry quota is significantly reduced due, presumably, to changes in responsiveness of ovarian follicles to gonadotro pins. Table I shows that exposure to LL markedly reduced the responsiveness of the anterior pituitary gland to LHRH.…”

Section: Effect Of Constant Light On Pituitary Responsiveness To Lhrhmentioning

confidence: 56%

Effects of Short-Term Constant Light on the Proestrous Luteinizing Hormone Surge and Pituitary Responsiveness in the Female Rat

Watts¹,

Fink²

1981

Neuroendocrinology

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We have investigated the effects of exposure to short-term constant light (LL) on the spontaneous, proestrous luteinizing hormone (LH) surge in the female rat. Exposure to LL during the 3 days preceding proestrus delayed and reduced the magnitude of the LH surge which was measured in blood samples taken from conscious animals through an intra-atrial catheter that had been implanted early on the morning of proestrus. The pituitary responsiveness to synthetic luteinizing hormone-releasing hormone (LHRH) in animals exposed to LL was reduced about 6-fold about the time of the LH surge compared with that in animals on a 14 h light-10 h dark (LD) regimen. In contrast to animals on LD, treatment of rats on LL with estrogen and progesterone after ovariectomy failed to restore to normal the pituitary responsiveness which is markedly reduced by ovariectomy. The implantation of a silicone-elastomer capsule containing 17β-estradiol into rats on LL after ovariectomy did not facilitate pituitary responsiveness. These results suggest that exposure of the female rats to LL for 3 days causes a shift in phase of the LH surge (which may represent a free-running LH rhythm) and reduces the magnitude of the LH surge by a mechanism which may involve a reduction in the sensitivity to estrogen of the centres involved in LHRH release.

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Induced Ovulation in Albino Rats Exposed to Constant Light

Cited by 100 publications

References 28 publications

Neural transplantation in hypogonadal (hpg) mice – physiology and neurobiology

Neural transplantation in hypogonadal (hpg) mice – physiology and neurobiology

Kisspeptin neurons mediate reflex ovulation in the musk shrew ( Suncus murinus )

Effects of Short-Term Constant Light on the Proestrous Luteinizing Hormone Surge and Pituitary Responsiveness in the Female Rat

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