当前位置： SCI文献检索 > ENDOCRINOLOGY期刊下所有文献 > Cessation of long day melatonin rhythms time puberty in a short day breeder.

Cessation of long day melatonin rhythms time puberty in a short day breeder.

Abstract：

:This study tested the hypothesis that in the female sheep, a short day (SD) breeder, puberty can occur normally in the absence of ambient short days. More specifically, the photoperiod cue timing the transition into adulthood is exposure to and then termination of a long day melatonin rhythm. Control lambs born in the spring were exposed to 5 weeks of long days (LD; 16 h of light, 8 h of darkness; 18-23 weeks of age) and were raised in SD (8 h of light, 16 h of darkness) at other times. As expected from previous studies, this alternating photoperiod sequence (SD-LD-SD) induced puberty at the normal age in autumn [33 +/- 2 weeks (mean +/- SEM); n = 6]. The other three groups were exposed only to LD from birth; the superior cervical ganglia were removed bilaterally at different ages to denervate the pineal gland in order to block transduction of subsequent LD cues. Puberty occurred normally (31 +/- 1 weeks; n = 7) after ganglionectomy at 23 weeks of age, indicating that ambient short days are not required to initiate reproductive cycles. LD are necessary, as evidenced by the results for the other two groups ganglionectomized neonatally at 4 weeks of age. With no further treatment, puberty was either delayed (n = 1) or did not occur during the first year of life (n = 5), after which the study ended. This delay was prevented in the other group of ganglionectomized lambs by a 5-week (18-23 weeks of age) exposure to LD melatonin patterns by means of 8-h melatonin infusions nightly; 12 weeks after melatonin replacement therapy, puberty occurred at the normal time (34 +/- 1 weeks; n = 6). The inference is that for puberty to occur in the female lamb the animal must be exposed to relatively limited periods of LD, followed by the blockade or absence of further LD cues (pineal denervation, termination of LD melatonin infusion, or presence of SD). This supports the concept that the LD of summer, followed by their disappearance in autumn, time puberty in the female sheep.

journal_name

Endocrinology

journal_title

Endocrinology

authors

Foster DL,Ebling FJ,Claypool LE,Woodfill CJ

doi

10.1210/endo-123-3-1636

subject

Has Abstract

pub_date

1988-09-01 00:00:00

pages

1636-41

issue

eissn

0013-7227

issn

1945-7170

journal_volume

123

pub_type

杂志文章

在线工具

Cessation of long day melatonin rhythms time puberty in a short day breeder.