Journal ArticleDOI
Serum profiles of follicle-stimulating hormone, luteinizing hormone and prolactin during the estrous cycle of the hamster.
TLDR
Serum LH levels were virtually constant throughout the estrous cycle, except for the preovulatory surge between 1300 hr and 1900 hr on Day 4 with a peak level at 1600 hr, and in marked contrast to these changes in serum levels of FSH.Abstract:
Follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin concentrations were determined by radioimmunoassay (NIAMD-Rat RIA) of sera from intact hamsters, which were decapitated at selected times during the 4-day estrous cycle. Serum FSH concentrations on Day 1 of the cycle (day of ovulation) were 2- to 6-fold greater than the levels on Day 2 and 5 to 12-fold greater than the mean, “basal,” level of FSH (53 ± 2 ng/ml; 80 hamsters) found during Day 3 and until 1200 hr, Day 4. There was a biphasic serum FSH pattern on Day 4 (proestrus) which was demarcated by the initiation of the preovulatory surge at 1400 hr, the peak level at 1600 hr, the decay of the surge by 2100 hr, and the subsequent elevation to the high levels present on Day 1. In marked contrast to these changes in serum levels of FSH, LH levels were virtually constant throughout the estrous cycle, except for the preovulatory surge between 1300 hr and 1900 hr on Day 4 with a peak level at 1600 hr. Prolactin concentrations varied a...read more
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Journal ArticleDOI
The Ovarian Cycle of the Bitch: Plasma Estrogen, LH and Progesterone
TL;DR: The results suggest that plasma estrogen initiates or potentiates the preovulatory release of progesterone may encourage the LH peak surge and the onset of behavioral estrus and that mechanisms exist that maintain elevated levels of plasma progestersone throughout pregnancy.
Journal ArticleDOI
Photoperiod control of reproductive development in the male Djungarian hamster (Phodopus sungorus).
TL;DR: The hypothesis that the short day-induced suppression of gonadotropins and PRL secretion during development blocked gonadal maturation in Djungarian or Siberian hamsters is supported.
Journal ArticleDOI
Aggressive behavior in female hamsters: the hormonal basis for fluctuations in female aggressiveness correlated with estrous state.
Owen R. Floody,Donald W. Pfaff +1 more
TL;DR: The roles of estrogen and progesterone are emphasized in synchronizing aggression with current reproductive state in naive female hamsters, indicating that pituitary hormones are not required for vigorous aggression.
Book ChapterDOI
Estrous Cyclicity in Mammals
TL;DR: In the previous chapter, several experimental manipulations designed to demonstrate that the secretions of the hypothalamus, the anterior pituitary, and the ovary can have stimulatory and inhibitory effects on one another were discussed.