Timing of Lh Release and Ovulation in the Cyclic Mouse

Bingel, Audrey S.; Schwartz, Neena B.

doi:10.1530/jrf.0.0190223

Cited by 36 publications

(25 citation statements)

References 9 publications

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“…As the master circadian pacemaker, the SCN, through entrainment to environmental light cycles, is responsible for the appropriate phasing of myriad physiological processes to environmental time (Pittendrigh and Daan, 1976). The SCN-derived signal, which is essential for the HPG axis cascade, has been shown to be restricted to just a few hours duration in the late afternoon of proestrus (Everett and Sawyer, 1950;Bingel and Schwartz, 1969). Previously, phase relations between activity onset and estrous onset were examined for hamsters exposed to progressive T cycles.…”

Section: Discussionmentioning

confidence: 99%

“…The existence of a crucial time window has been suggested before the discovery of the SCN as a circadian pacemaker (Everett and Sawyer, 1950;Bingel and Schwartz, 1969), and, nowadays, the crucial time window is most probably explained as the phase synchrony between the SCN signal and the timing of GnRH responsiveness (Miller and Takahashi, 2013, review). In this scheme, along with adjustments of the period of T cycles, adjustments of the LD ratio also may be effective in achieving the appropriate phase relationship between the crucial time window and the LD cycle.…”

Section: Discussionmentioning

confidence: 99%

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Recovery from Age-Related Infertility under Environmental Light-Dark Cycles Adjusted to the Intrinsic Circadian Period

et al. 2015

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Female reproductive function changes during aging with the estrous cycle becoming more irregular during the transition to menopause. We found that intermittent shifts of the light-dark cycle disrupted regularity of estrous cycles in middle-aged female mice, whose estrous cycles were regular under unperturbed 24-hr light-dark cycles. Although female mice deficient in Cry1 or Cry2, the core components of the molecular circadian clock, exhibited regular estrous cycles during youth, they showed accelerated senescence characterized by irregular and unstable estrous cycles and resultant infertility in middle age. Notably, tuning the period length of the environmental light-dark cycles closely to the endogenous one inherent in the Cry-deficient females restored the regularity of the estrous cycles and, consequently, improved fertility in middle age. These results suggest that reproductive potential can be strongly influenced by age-related changes in the circadian system and normal reproductive functioning can be rescued by the manipulation of environmental timing signals.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Recovery from Age-Related Infertility under Environmental Light-Dark Cycles Adjusted to the Intrinsic Circadian Period

et al. 2015

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“…2b), it is possible that pituitary refractoriness may be brought about, at least in part, by previous exposure to increased levels of progesterone in the circulation. This does not exclude the possibility that this refractoriness may also be due partly to exposure to increased levels of other sex steroids, especially oestrogens, and to a rapid depletion of a readily releasable pool of LH. As in small rodents (Alleva & Umberger, 1966;Bingel & Schwartz, 1969;Norman, Blake & Sawyer, 1973;reviews: Everett, 1961reviews: Everett, , 1972Schwartz, 1969Schwartz, , 1973, spontaneous pre-ovulatory discharges of LH occur only during a restricted period of the day in hens maintained under constant lighting conditions (e.g. lights on from 07.00 to 21.00 h) (Wilson & Sharp, 1973).…”

Section: Discussionmentioning

confidence: 99%

Changes in Plasma Concentrations of Luteinizing Hormone After Injection of Progesterone at Various Times During the Ovulatory Cycle of the Domestic Hen (Gallus Domesticus)

Wilson¹,

Sharp²

1975

Journal of Endocrinology

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Changes in plasma LH concentrations after i.m. injections of 0-5 mg progesterone/kg at various stages of the ovulatory cycle were measured by radioimmunoassay. Four types of response were observed. (1) When the steroid was injected between 4 h after and 12 h before an ovulation, LH levels started to rise after 15--45 min and reached peak values within 90--120 min. The mean maximal incremental change in the level of LH was 1-58 +/- 0-10(S.E.M.) ng/ml (n = 37). (2) In contrast, when progesterone was injected 12--8 h before ovulation, i.e. immediately before a spontaneous pre-ovulatory LH surge, the resulting mean maximal incremental change in LH level, 0-79 +/- 0-12 ng/ml (n = 9), was significantly smaller (P less than 0-001). (3) If progesterone was injected 8--4 h before ovulation, i.e. when pre-ovulatory LH levels were rising, they immediately started to rise more rapidly and reached peak values within 45 min. The maximal incremental change in the level of LH under these circumstances, 2-34 +/- 0-20 ng/ml (n = 12), was significantly greater (P less than 0-001) in both cases) than the changes observed in the responses 1 and 2 described above. (4) Levels of LH generally showed no incremental change in response to injections of progesterone given 4--0 h before ovulation, i.e. when pre-ovulatory LH levels were falling. It was concluded that the type of change in plasma LH levels induced by progesterone depended upon the stage of the ovulatory cycle at which the steroid was injected.

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“…4 One of the 5 ovulated incompletely; stimulated follicles [Bingel and Schwartz, 1969b] were found also. 5 p < 0.001.…”

Section: Proestrous Autopsiesmentioning

confidence: 98%

Acute Effects of Ovariectomy and Sham Ovariectomy on Pituitary-Ovarian Phenomena in the Mouse

1975

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Four- and 5-day cyclic mice housed with and without males, respectively, were autopsied at 10 a.m. on proestrus (P) or estrus (E) after no treatment, or after ovariectomy (Ovax) or sham Ovax at 10 a.m. or 4 p.m. on one of the preceding 3 days. Results indicate the ovaries must be in situ between 4 p.m. the day before P and 10 a.m. the day of P for a normal proestrous uterine weight increase to occur in both 4- and 5-day cyclic mice. For estrous cornification to occur, ovaries must be in situ between 10 a.m. and 4 p.m. on diestrus (D) in 4-day cyclic mice, and between 4 p.m. on D-I and 10 a.m. on D-II in 5-day cyclic mice. Sham Ovax tended to inhibit ovulation in both 4- and 5-day cyclic mice. The effects of both Ovax and sham Ovax on proestrous and estrous pituitary LH values were variable. Timing of the feedback relationship between ovary and hypothalamus-pituitary in mice may be imprecise, leading to easy disruption of the estrous cycle in this species.

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Timing of Lh Release and Ovulation in the Cyclic Mouse

Cited by 36 publications

References 9 publications

Recovery from Age-Related Infertility under Environmental Light-Dark Cycles Adjusted to the Intrinsic Circadian Period

Recovery from Age-Related Infertility under Environmental Light-Dark Cycles Adjusted to the Intrinsic Circadian Period

Changes in Plasma Concentrations of Luteinizing Hormone After Injection of Progesterone at Various Times During the Ovulatory Cycle of the Domestic Hen (Gallus Domesticus)

Acute Effects of Ovariectomy and Sham Ovariectomy on Pituitary-Ovarian Phenomena in the Mouse

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