Long-Term Reproductive Effects of a Single Long Day in the Siberian Hamster (Phodopus sungorus

摘要: Testicular regression was prevented or attenuated in Siberian hamsters exposed to a single 1- 4-h extension of the 16-h photophase at 18 days age and subsequently maintained short photoperiod (8L:16D) through Day 35. weights on 35 were not correlated with duration active phase wheel running time activity onset after transfer 8L:16D photoperiod. Wheel-running stably entrained light-dark cycle by age. Progonadal effects 33-h light pulse greatest age, still evident 30 days, but undetectable older hamsters. In female hamsters, longer day weaning associated increased fecundity several weeks later. Long photoperiods accelerated development antral ovarian follicles, exposure males necessary induce ovulation before 60 The interval beginning shortly is one heightened responsiveness changes length (DL); increasing DL this may prolong breeding season when decreases summer solstice. We suggest that long-term acute treatments reproduction are mediated sustained melatonin secretion induced reprogramming circadian oscillators.