Hormonal and neurotransmitter regulation of GnRH gene expression and related reproductive behaviors

Sagrillo, Cathleen A.; Grattan, David R.; McCarthy, Margaret M.; Selmanoff, Michael

doi:10.1007/bf02359383

Cited by 80 publications

(49 citation statements)

References 360 publications

(416 reference statements)

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“…A similar decrease in GnRH mRNA levels has been reported in the rat (24,25), although this finding is controversial (reviewed in Ref. 21). Other researchers found no effect (26) or an increase (27) in GnRH mRNA levels after ovariectomy in female rats.…”

Section: Species Comparisonssupporting

confidence: 62%

“…In the rat, however, in those studies in which changes were reported (reviewed in Ref. 21), increases in either cellular GnRH mRNA levels or GnRH mRNA cell numbers occurred in the organum vasculosum of the lamina terminalis/rostral preoptic area during the estrogen-induced LH surge (10,15,22,23). There is a species difference in the temporal relationship between the changes observed in GnRH mRNA levels and the LH surge.…”

Section: Species Comparisonsmentioning

confidence: 96%

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Changes in Mediobasal Hypothalamic Gonadotropin-Releasing Hormone Messenger Ribonucleic Acid Levels Induced by Mating or Ovariectomy in a Reflex Ovulator, the Ferret*

1999

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Section: Species Comparisonssupporting

confidence: 62%

Section: Species Comparisonsmentioning

confidence: 96%

Changes in Mediobasal Hypothalamic Gonadotropin-Releasing Hormone Messenger Ribonucleic Acid Levels Induced by Mating or Ovariectomy in a Reflex Ovulator, the Ferret*

1999

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“…These data agree with results for the rat (66,115,139,235), which also failed to detect any significant changes in hypothalamic GnRH mRNA levels after steroidal manipulations. By contrast, there are also numerous reports (reviewed in 83,190) showing either increases or decreases in POA GnRH mRNA levels after gonadectomy in rats, although these changes in GnRH mRNA levels are relatively small compared to the amount of LH released following gonadectomy. Thus, the postgonadectomy rise in LH does not seem to depend on dramatic increases in hypothalamic GnRH gene transcription in either rats or ferrets.…”

Section: Gnrh Biosynthesismentioning

confidence: 96%

“…Numerous studies (reviewed in 83,190) have been conducted in spontaneously ovulating species, including rats and sheep, to determine whether the steroid-induced preovulatory release of GnRH depends, in part, on increased GnRH gene transcription in POA neurons. Unfortunately, results obtained in these studies have been inconclusive.…”

Section: Neuronal Fos/gnrh Colocalizationmentioning

confidence: 99%

Neuroendocrine Regulation of GnRH Release in Induced Ovulators

Bakker

Baum

2000

Frontiers in Neuroendocrinology

178

135

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GnRH is the key neuropeptide controlling reproductive function in all vertebrate species. Two different neuroendocrine mechanisms have evolved among female mammals to regulate the mediobasal hypothalamic (MBH) release of GnRH leading to the preovulatory secretion of LH by the anterior pituitary gland. In females of spontaneously ovulating species, including rats, mice, guinea pigs, sheep, monkeys, and women, ovarian steroids secreted by maturing ovarian follicles induce a pulsatile pattern of GnRH release in the median eminence that, in turn, stimulates a preovulatory LH surge. In females of induced ovulating species, including rabbits, ferrets, cats, and camels, the preovulatory release of GnRH, and the resultant preovulatory LH surge, is induced by the receipt of genital somatosensory stimuli during mating. Induced ovulators generally do not show "spontaneous" steroid-induced LH surges during their reproductive cycles, suggesting that the positive feedback actions of steroid hormones on GnRH release are reduced or absent in these species. By contrast, mating-induced preovulatory surges occasionally occur in some spontaneously ovulating species. Most research in the field of GnRH neurobiology has been performed using spontaneous ovulators including rat, guinea pig, sheep, and rhesus monkey. This review summarizes the literature concerning the neuroendocrine mechanisms controlling GnRH biosynthesis and release in females of several induced ovulating species, and whenever possible it contrasts the results with those obtained for spontaneously ovulating species. It also considers the adaptive, evolutionary benefits and disadvantages of each type of ovulatory control mechanism. In females of induced ovulating species estradiol acts in the brain to induce aspects of proceptive and receptive sexual behavior. The primary mechanism involved in the preovulatory release of GnRH among induced ovulators involves the activation of midbrain and brainstem noradrenergic neurons in response to genital-somatosensory signals generated by receipt of an intromission from a male during mating. These noradrenergic neurons project to the MBH and, when activated, promote the release of GnRH from nerve terminals in the median eminence. In contrast to spontaneous ovulators, there is little evidence that endogenous opioid peptides normally inhibit MBH GnRH release among induced ovulators. Instead, the neural signals that induce a preovulatory LH surge in these species seem to be primarily excitatory. A complete understanding of the neuroendocrine control of ovulation will only be achieved in the future by comparative studies of several animal model systems in which mating-induced as well as spontaneous, hormonally stimulated activation of GnRH neurons drives the preovulatory LH surge. KEY WORDS: GnRH; MBH; induced ovulators; neuroendocrine regulation; preovulatory LH surge; spontaneous ovulators. © 2000 Academic Press Address correspondence and reprint requests to M. J. Baum at Dept. Biology, Boston University, 5 Cummington Street, Boston...

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“…Furthermore, basal levels of LH were elevated in peripubertal females 3 weeks after ovariectomy and these animals were more responsive to steroid-induced LH secretion. One possible explanation for these results is that as the interval between ovariectomy and steroid replacement increased, circulating levels of gonadotropins increased due to loss of negative feedback (Sagrillo et al 1996, Gore & Roberts 1997, Herbison 1998). Loss of negative feedback causes the pituitary to be more responsive to GnRH stimulation (Legan et al 1973) and results in increased LH release following steroid hormone treatment.…”

Section: Discussionmentioning

confidence: 99%

Effect of steroids and nitric oxide on pituitary hormone release in ovariectomized, peripubertal rats

Russell

Murphree²,

Janik³

et al. 2005

Reproduction

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The purpose of this study was to determine the effects of the duration of steroid depletion on the steroid-induced luteinizing hormone and prolactin surges in ovariectomized, peripubertal female rats. Additionally, the role of nitric oxide (NO) in mediating the surge responses was determined. Peripubertal, 6-week-old, female Sprague-Dawley rats were ovariectomized. One or three weeks later, animals were injected with 17b-estradiol (50 mg, sc) followed 48 h later by progesterone (2.5 mg, sc). Effects of NO were examined by administering L-arginine (300 mg/kg, ip). The response of ovariectomized, adult females to steroid treatment was also determined. One and three weeks after ovariectomy, steroid replacement produced an LH and prolactin surge in peripubertal animals. However, both the magnitude and duration of the LH surge was greater 3 weeks after ovariectomy. While L-arginine significantly enhanced the magnitude of the LH surge 1 week after ovariectomy, by 3 weeks L-arginine caused a decrease in the duration, but not the magnitude of the surge. In contrast, L-arginine did not affect either the magnitude or duration of the prolactin surge one week after ovariectomy, but diminished the magnitude after 3 weeks of steroid depletion. In adults, steroids induced significant increases in both LH and prolactin. These results demonstrate that sensitivity to NO stimulation of LH, but not prolactin secretion, is modulated by the duration of gonadal steroid hormone depletion. The differences in the responsiveness of LH and prolactin to steroid-induced stimulation in peripubertal animals demonstrate that these hormones are regulated by NO through different mechanisms.

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Hormonal and neurotransmitter regulation of GnRH gene expression and related reproductive behaviors

Cited by 80 publications

References 360 publications

Changes in Mediobasal Hypothalamic Gonadotropin-Releasing Hormone Messenger Ribonucleic Acid Levels Induced by Mating or Ovariectomy in a Reflex Ovulator, the Ferret*

Changes in Mediobasal Hypothalamic Gonadotropin-Releasing Hormone Messenger Ribonucleic Acid Levels Induced by Mating or Ovariectomy in a Reflex Ovulator, the Ferret*

Neuroendocrine Regulation of GnRH Release in Induced Ovulators

Effect of steroids and nitric oxide on pituitary hormone release in ovariectomized, peripubertal rats

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