Modulation by Vitamin D3 of Action of FSH on the Sertoli Cells in Immature Siberian Hamsters Raised in Long or Short Photoperiod
Follicle stimulating hormone (FSH) acts directly on Sertoli cells (Sc) to stimulate their secretory activity and is important for initiation of testicular growth (1, 2). A role of metabolites of vitamin D3 (D3) in mediating the effects of photoperiod on physiological processes has been suggested (3). Demonstration of D3 receptors in the testes (4) and especially in the Sc (5) raised the possibility of a direct effect of D3 on the Sc. In the present study, effects of FSH and D3 on lactate production by the Sc were studied in vitro using cultures of Sc from juvenile Siberian hamsters (Phodopus sungorus). Lactate is the preferred energy substrate of the germ cells, and stimulation of Sc lactate production by FSH is believed to represent an important mechanism of FSH action on spermatogenesis (6). To further pursue the relationship between the actions of FSH and D3, we have also examined the effects of D3-treatment in vivo on testicular growth. The animals raised in long photoperiod (LD; 16L:8D) or short photoperiod (SD;6L:18D) were given daily injections of D3 between 18 and 28 days of age. During this period, endogenous FSH levels in Siberian hamsters are very high in animals exposed to LD and extremely low or nondetectable in those exposed to SD (7).
KeywordsFollicle Stimulate Honnone Sertoli Cell Short Photoperiod Follicle Stimulate Honnone Receptor Testicular Weight
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