PMID: 2509675Jan 1, 1989Paper

Comparison of the effects of short photoperiod exposure and melatonin treatment in ovariectomized LSH/SsLaK hamsters

Journal of Pineal Research
U E Hauser, B Benson

Abstract

The object of this study was to compare the effects of short photoperiod (SP) and melatonin (MEL) treatment on the reproductive axis in ovariectomized LSH/SsLak hamsters. Animals acclimatized in long photoperiods (LP) (14L:10D) and showing regular estrous cycles were ovariectomized. Half of the operated hamsters received Silastic capsules containing 17-beta estradiol (E2). On the following day the animals were further subdivided into three groups: the animals in one group received daily afternoon injects of melatonin (MEL), those in a second group were given the vehicle, and animals in the third group were transferred from LP to SP (8L:16D). All animals were killed after 30 days. In hamsters without E2 replacement, MEL or SP exposure significantly suppressed serum and pituitary FSH levels, although MEL was more effective in this regard. On the other hand, SP exposure did not change serum FSH levels in animals with E2 implants, whereas MEL effectively suppressed them. SP or MEL reduced serum LH levels to a similar extent in the absence of E2 replacement, yet in animals with E2 implants only MEL significantly lowered LH levels below LP E2-treated controls. This was in contrast to effects on the pituitary where both treatments wer...Continue Reading

References

Jul 1, 1977·Journal of Reproduction and Fertility·E L Bittman, I Zucker
Jan 1, 1987·Neuroendocrinology·U E Hauser, B Benson
Jul 1, 1985·Neuroendocrinology·G M BrownL J Grota
Jun 1, 1969·General and Comparative Endocrinology·R J Reiter
Mar 1, 1983·Proceedings of the Society for Experimental Biology and Medicine·M J SoaresF Talamantes

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