Induced LH Surges in the Rhesus Monkey: Strength-Duration Characteristics of the Estrogen Stimulus12

Karsch, Fred J.; Weick, Richard F.; Butler, Walter; Dierschke, Donald J.; Krey, L.C.; Weiss, Gerson; Hotchkiss, J.; Yamaji, Taiki; Knobil, E.

doi:10.1210/endo-92-6-1740

Cited by 201 publications

(72 citation statements)

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“…For instance, in female rats (reviewed in 108) maintained on 14-h light and 10-h darkness (lights on between 05:00 and 19:00 h) the preovulatory LH surge typically occurs on the day of proestrus between 14:00 and 16:00 h. It is unclear to what extent this timing of the LH surge to the light/dark cycle can be applied to other spontaneously ovulating species. In the rhesus monkey (112), for example, the estradiol-induced preovulatory LH surge does not appear to be coupled to the light/dark cycle. By contrast, in humans (65), the preovulatory LH surge usually occurs in the morning around 9:00 h. Destruction of the SCN (5, 27) or exposure to constant illumination (225) leads to a cessation of ovarian cyclicity and induces a state of persistent estrus in female rats.…”

Section: Regulation Of Gnrh Secretion and Biosynthesis By Ovarian Stementioning

confidence: 99%

Neuroendocrine Regulation of GnRH Release in Induced Ovulators

Bakker

Baum

2000

Frontiers in Neuroendocrinology

180

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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Section: Regulation Of Gnrh Secretion and Biosynthesis By Ovarian Stementioning

confidence: 99%

Neuroendocrine Regulation of GnRH Release in Induced Ovulators

Bakker

Baum

2000

Frontiers in Neuroendocrinology

180

135

View full text Add to dashboard Cite

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“…5, the mid-cycle surge of both LH and FSH was not immediately suppressed in spite of the continuous infusion of a large dose of estradiol. Discussion Karsh et al(1973) reported that increments in circulatory estrogen which exceeded a threshold of approximately 100pg/ml, if sustained around 36-42 hr, induced LH surges in the monkeys of the early follicular phase. In the present study, the similar positive feedback action of estrogen is demonstrated in women.…”

Section: Subjectsmentioning

confidence: 95%

“…In monkeys, a precise interrelationship between the strength-duration characteristics of the estrogen stimulus and the LH responses was studied by Karsh et al (1973).…”

mentioning

confidence: 99%

Analysis of the positive feedback effect of estrogen on the release of gonadotropin in women.

Araki¹,

Minakami²,

Konuma³

et al. 1978

Endocrinol Japon

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“…There is considerable experimental evidence linking this oestradiol rise to the LH surge. In the monkey, an LH surge similar to that seen spontaneously at mid-cycle (positive feedback loop of oestradiol) can be induced during the early follicular phase (at a time of the cycle when spontaneous LH surges are not seen) by administering oestradiol in amounts simulating those seen at mid-cycle (Karsch et al, 1973). Inactivation of the oestradiol signal by immunization to oestrogen blocks the mid-cycle LH rise and ovulation; in these immunized monkeys, the LH surge and ovulation can be restored by diethylstilboestrol, a synthetic oestrogen not recognized by antioestradiol antibodies (Ferin, Dyrenfurth, Cowchock, Warren & Vande Wiele, 1974b).…”

Section: Gonadotrophin Release Is Pulsatilementioning

confidence: 99%