Abstract:
:Testicular growth was monitored in male ferrets subjected to one of the following photoperiodic treatments begun at weaning (8 weeks of age): 8 hr light/day (short days), 18 hr light/day (long days), or short days followed by transition to long days at either 10, 12, or 14 weeks of age. Mean ages to achieve adult testis width of greater than or equal to 12 mm were 27.5 +/- 1.3, 25.0 +/- 1.5, 23.6 +/- 2.9, 20.0 +/- 0.8, and 21.2 +/- 1.0 weeks in ferrets raised from weaning in long days, raised from weaning in short days, and transferred from short to long days at 10, 12, or 14 weeks, respectively. This criterion was met significantly earlier by ferrets experiencing the photoperiod transition at 12 or 14 weeks of age than by ferrets housed in long days from weaning. At the end of the experiment (30 weeks of age), mean testis width was significantly smaller in ferrets raised in long days from weaning or transferred to long days at 10 weeks of age, compared to that of the other three groups (p less than 0.05). In a second experiment, photoperiod experience with long or short days was begun at birth, and testicular size was monitored for a longer period of time. The time courses for testicular maturation were similar to that obtained when these treatments began at weaning. By 40 weeks of age, mean testis width of ferrets raised in long days was comparable to that of ferrets raised in short days. A third study determined that the retarded testicular growth observed in ferrets exposed to long days from weaning was correlated with diminished pulsatile luteinizing hormone (LH) secretion. At 28 weeks of age, mean LH pulse frequency was 0.86 +/- 0.09 pulses/hr in ferrets undergoing spontaneous puberty in short days or photoinduced puberty after a short-to-long-day transition; pulse frequency was significantly lower (0.46 +/- 0.26 pulses/hr; p less than 0.05) in ferrets raised in long days. These results indicate that gonadal growth can be precociously induced in male ferrets by exposure to a sequence of short days followed by long days, and that the absence of sufficient prepubertal exposure to short days compromises pulsatile LH secretion and rate of gonadal growth. Experience with short days during development may be necessary for manifestation of stimulatory responses to long days.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Sisk CLdoi
10.1177/074873049000500301subject
Has Abstractpub_date
1990-10-01 00:00:00pages
177-86issue
3eissn
0748-7304issn
1552-4531journal_volume
5pub_type
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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journal_title:Journal of biological rhythms
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abstract::Mice homozygous for a dominant-negative allele of the Clock gene (Clock (Δ19/Δ19)) have slightly but significantly decreased male fertility. The molecular mechanism for this reduction in fertility is unknown. In the present study, we used a small hairpin RNA (shRNA) strategy to specifically knock down the Clock gene e...
journal_title:Journal of biological rhythms
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更新日期:2014-06-01 00:00:00
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journal_title:Journal of biological rhythms
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更新日期:1999-12-01 00:00:00