Seasonal Variations in the Onset of Puberty in Rats1

Ramaley, Judith A.; Bunn, E.L.

doi:10.1210/endo-91-2-611

Cited by 43 publications

(22 citation statements)

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“…Rats reared in 8:16 or LL were placed in a 14:10 cycle at weaning. At various ages, the animals were killed by decapita tion; the trunk blood was collected, and the serum was saved for determination of corti costerone by a fluorometric procedure [Ramaley, 1972], The data were evaluated by means of Duncan's multiple range test. Times shown are based on the midpoint of the dark period (colony midnight) which is 2 h after local midnight (Central Daylight Time).…”

Section: Methodsmentioning

confidence: 99%

Entrainment of the Adrenal Rhythm to Photoperiod Prior to Puberty: Effects of Early Experience on the Adrenal Rhythm and Puberty

Ramaley¹

1976

Neuroendocrinology

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The purpose of this study was to determine whether exposure to a cycle of light and dark before the onset of the adrenal rhythm would be necessary in order for rats to develop a normal rhythm of peripheral corticosterone when placed in a test photoperiod at weaning age. Rats were reared in constant light (LL) until weaning age, at which time they were placed in a cycle of 14 h light, 10 h dark (14:10). Females born and reared in 14:10 had peak corticosterone values at 14.00 h on days 22 and 26, and at 18.00 h on days 32 and 36. Males did not display a clear-cut rhythm at 22 or 26 days but had peak corticosterone at 18.00 h on days 32 and 36. Males and females reared in LL until weaning had no rhythm as a group in 14:10 at 24 days of age, but had a corticosterone peak at 18.00 h on days 28 and 40. Females born and reared in LL and exposed to 14:10 for 1 day developed an adrenal rhythm regardless of the age at exposure, but only 25 day old animals showed a normal pattern for their age group. Puberty was advanced in rats exposed to a single day of 14:10 at 25 days of age, but was delayed in younger rats (22 days old), and was unaffected by light exposure in older rats (28 days of age). It can be concluded that early exposure to light-dark cycles is not required for the normal development of an adrenal rhythm in the weanling rat, and that the setting of the corticosterone rhythm to the photoperiod can occur quite rapidly. Rats at 25-26 days of age are able to respond differently to a light cycle challenge than younger rats. A photoperiodic stimulus at that time can advance the onset of puberty.

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Section: Methodsmentioning

confidence: 99%

Entrainment of the Adrenal Rhythm to Photoperiod Prior to Puberty: Effects of Early Experience on the Adrenal Rhythm and Puberty

Ramaley¹

1976

Neuroendocrinology

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“…They suggested that the transient prepuberal rise of progesterone was caused by either premature ovulation or follicular luteinization within the ovary. Alternatively, the rise may be of adrenal origin as reported by Ramaley and Bunn (1972) for the female rat.…”

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confidence: 87%

Source of Circulating Progesterone in Prepubertal Ewes

Berardinelli

Dailey

Butcher

et al. 1980

Biology of Reproduction

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“…Acute stress during proestrus in the adult can alter the timing of the release of luteinizing hormone in rats [Neguin and Schwartz, 1971]. Adrenalectomy prior to 26 days of age can delay the onset of normal puberty [Gorski and Lawton, 1972;Ramaley and Bunn, 1972] in the rat. Manipulations of the adrenal can also alter the timing of sexual behavior during the mouse estrous cycle [Hansult et al, 1972], All of these results suggest that the adrenal plays a role in fertility.…”

Section: Discussionmentioning

confidence: 99%

“…Injections of corticoids on the day of proestrus can facilitate ovulation [Ying and Meyer, 1969]. During normal puberty, blood levels of cor ticosterone become elevated at the time of vaginal opening [Ramaley, 1972], Adrenalectomy prior to PMS administration considerably re duces the number of animals that ovulate and the weight changes ob tained in the ovaries [Ramaley, 1973;Mandl, 1954]. From these results it can be concluded that in the immature rat the adrenal appears to be involved in gonadal responses to gonadotrophin.…”

Section: Discussionmentioning

confidence: 99%

Adrenal-Gonadal Relations and Fertility: The Effects of Repeated Stress upon the Adrenal Rhythm

Paris¹,

Ramaley²

1974

Neuroendocrinology

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We have previously reported that immobilization stress administered twice daily over a one-week period results in delayed puberty and reduced fertility in C57/B16 mice exposed to the stress prior to or at the onset of puberty. Exposure to the same stress in adult cycling or non-cycling females led to larger litter sizes and a greater incidence of conception. The purpose of the present study was to determine whether the effects of stress on fertility were associated with changes in the amplitude or rhythm of corticosterone concentration in the blood. Prepubertal mice subjected to daily immobilization stress showed a shift in the peak of the daily corticosterone rhythm which persisted for at least a week after the stress periods were terminated. In adult female mice housed near males in order to maintain an estrous cycle, the same stress caused a reversal of the daily corticosterone rhythm with peak levels of corticosterone occurring during the midpoint of the light interval rather than shortly after the onset of darkness. Old females maintained in large groups and showing no evidence of regular estrous cycles had no evidence of a 24-h corticosterone rhythm before stress. During the week after stress had been discontinued these mice developed a daily rhythm. It can be concluded that in mice the presence of adrenal rhythm is associated with fertility and the absence of such a rhythm is correlated with infertility.

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Seasonal Variations in the Onset of Puberty in Rats1

Cited by 43 publications

References 0 publications

Entrainment of the Adrenal Rhythm to Photoperiod Prior to Puberty: Effects of Early Experience on the Adrenal Rhythm and Puberty

Entrainment of the Adrenal Rhythm to Photoperiod Prior to Puberty: Effects of Early Experience on the Adrenal Rhythm and Puberty

Source of Circulating Progesterone in Prepubertal Ewes

Adrenal-Gonadal Relations and Fertility: The Effects of Repeated Stress upon the Adrenal Rhythm

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