The Effect of Sterile Copulation on Time of Ovulation in Dairy Heifers

Marion, G. B.; Smith, Vearl R.; Wiley, Tisha R. A.; Barrett, G.R.

doi:10.3168/jds.s0022-0302(50)91985-0

Cited by 50 publications

(12 citation statements)

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“…Despite this contrast in the primary stimulus for releasing GnRH/LH to initiate ovulation in these species, there may be similar neural processes for receiving sensory and hormonal inputs. For example, reports exist in rabbits of steroid-induced LH release [7,8] and in domestic animals [9,10] of coitus-associated enhanced LH release and/or ovulation. Indeed, coitus-induced ovulation in women has been suggested [11], although Quadri et al [12] found no fluctuations in serum LH levels in cycling rhesus monkeys after coitus.…”

Section: Introductionmentioning

confidence: 99%

Coital and Estrogen Signals: A Contrast in the Preovulatory Neuroendocrine Networks of Rabbits and Rhesus Monkeys1

Spies

Pau

Yang

1997

Biology of Reproduction

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Certain brain peptides and catecholamines function in activating the hypothalamohypophysial-ovarian axis in both rabbits and rhesus monkeys. The natural stimulus for a surge release of GnRH is coitus in rabbits, whereas the initial excitatory signal is ovarian steroids in monkeys. Despite this contrast in initial signals, specific neurochemicals may serve as common stimuli for GnRH secretion in both species. Evidence is presented that one such substance is norepinephrine (NE), which is released from the mediobasal hypothalamus before, or simultaneously with, GnRH, although the latency in time between stimulus (coitus/estrogen) and response (GnRH/LH release) is very different. Moreover, both stimuli activate NE gene expression in cells located in the brainstem. We suggest that the brainstem is an extra-hypothalamic site where preovulatory signals for GnRH surges are developed in both rabbits and primates.

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Section: Introductionmentioning

confidence: 99%

Coital and Estrogen Signals: A Contrast in the Preovulatory Neuroendocrine Networks of Rabbits and Rhesus Monkeys1

Spies

Pau

Yang

1997

Biology of Reproduction

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“…Stewart (1952), by repeated clinical examination of animals that had apparently failed to conceive and had returned to oestrus at an interval greater than the average length of the oestrous cycle, concluded that this was most frequently due to the persistence of a corpus luteum that had been associated with a pregnancy. Further, it has been shown that mating with a vasectomized bull had no effect on the length of the subsequent return interval (Marion, Smith, Wiley & Barrett, 1950 Recent work by Dawson (1958) suggests that the counting of what he terms miniature corpora albicantia could be an aid in estimating temporary preg¬ nancy of 2 to 5 months duration.…”

Section: Methods Of Studymentioning

confidence: 99%

Prenatal Mortality in Farm Animals

Hanly¹

1961

Reproduction

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“…The spontaneously mutant hpg mouse (37), which bears a specific deletion in the GnRH gene, showed mating-induced but not spontaneous ovulation when brain grafts containing GnRH neurons were implanted into the third ventricle (77). In cattle (141,204), mating during the first 6 -8 h of behavioral estrus advanced the preovulatory LH surge and resultant ovulation. Taken together, these observations suggest that the neural circuitry underlying the reflexive release of LH is present in some spontaneously ovulating species.…”

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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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The Effect of Sterile Copulation on Time of Ovulation in Dairy Heifers

Cited by 50 publications

References 3 publications

Coital and Estrogen Signals: A Contrast in the Preovulatory Neuroendocrine Networks of Rabbits and Rhesus Monkeys1

Coital and Estrogen Signals: A Contrast in the Preovulatory Neuroendocrine Networks of Rabbits and Rhesus Monkeys1

Prenatal Mortality in Farm Animals

Neuroendocrine Regulation of GnRH Release in Induced Ovulators

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