Biology of Reproduction, Vol 24, 287-292, Copyright © 1981 by Society for the Study of Reproduction

Prolactin Release in Golden Hamsters: Photoperiod and Gonadal Influences

¹ Department of Biobehavioral Sciences, University of Connecticut, Storrs, Connecticut 06268
² Physiology Section, School of Live and Health Sciences, University of Delaware, Newark, Delaware 19711

Serum prolactin (PRL) in male golden hamsters was determined under a variety of experimental conditions. The pattern of daily PRL release appears to be only slightly altered by mild stress, and serum PRL levels are unaltered by castration. Exposure to short photoperiod induces a marked decline in serum PRL titers. Serum PRL levels remain depressed for 19-21 weeks of short-day treatment and then increase spontaneously. The spontaneous elevation of PRL titer appears to be relatively independent of testicular influence since it occurs at the same time in intact and castrated males, as well as in castrated males bearing testosterone implants. Spontaneous PRL release in intact males bearing testosterone implants was delayed 2 weeks. Changes in serum PRL concentrations may have a role in mediating the inhibition of testis function which occurs during exposure to short photoperiod.

Note:
ACKNOWLEDGMENTS The authors wish to thank the NIAMDD Rat Pituitary Hormone Program for their gift of reagents used in the prolactin assays.

This article has been cited by other articles:

				M. J. Paul, N. T. George, I. Zucker, and M. P. Butler Photoperiodic and hormonal influences on fur density and regrowth in two hamster species Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2007; 293(6): R2363 - R2369. [Abstract] [Full Text] [PDF]

				W. Jin, C. B. Herath, M. Yoshida, K. Y. Arai, E. Saita, S. Zhanquan, L. Ren, G. Watanabe, N. P. Groome, and K. Taya Inhibin B Regulating Follicle-Stimulating Hormone Secretion During Testicular Recrudescence in the Male Golden Hamster J Androl, November 1, 2002; 23(6): 845 - 853. [Abstract] [Full Text] [PDF]

				T. J. Bartness, G. E. Demas, and C. K. Song Seasonal Changes in Adiposity: the Roles of the Photoperiod, Melatonin and Other Hormones, and Sympathetic Nervous System Experimental Biology and Medicine, June 1, 2002; 227(6): 363 - 376. [Abstract] [Full Text] [PDF]

				K. Krajnak, J. Manzanares, K. J. Lookingland, and A. A. Nunez The Effect of Short-Photoperiod Exposure on Tuberoinfundibular Dopamine Neurons in Male and Female Syrian Hamsters J Biol Rhythms, July 1, 1994; 9(2): 125 - 135. [Abstract] [PDF]

				J. Glass and G. Lynch Melatonin: identification of sites of antigonadal action in mouse brain Science, November 13, 1981; 214(4522): 821 - 823. [Abstract] [PDF]