311. Adult Sertoli cells proliferate in response to exogenous follicle stimulating hormone in the adult photo-inhibited Djungarian hamster

Abstract

Sperm production relies on nutritional and structural support from Sertoli cells. Sertoli cells undergo maturational changes (e.g. cessation of proliferation and formation of the blood–testis barrier) around the onset of puberty in higher mammals1 and maturational failure has been associated with some infertility syndromes and testicular malignancies2. The Sertoli cell population is considered to be stable and unmodifiable by hormones after puberty in mammals, although recent data using the adult Djungarian hamster showed that Sertoli cell numbers decreased by 35% in the absence of serum gonadotrophins, and returned to control levels by short-term replacement of follicle stimulating hormone (FSH)3. Therefore, the aims of this study were to (i) quantify the proliferative activity of Sertoli cells in the hormonally manipulated Djungarian hamster, and (ii) examine the localisation of several tight junction proteins as markers of the blood–testis barrier. Long day (LD) photoperiod (16L : 8D) adult hamsters were exposed to short day (SD) photoperiod (8L : 16D) for 11 weeks to suppress gonadotrophins and then received FSH for up to 10 days. Sertoli cell proliferation was assessed immunohistochemically by the colocalisation of GATA-4 and PCNA, and quantified by stereology. Tight junction proteins (occludin and ZO-1) were colocalised using confocal microscopy. Sertoli cell proliferation in both the LD and SD controls was minimal; however, in response to FSH treatment proliferation was upregulated within 4 days compared with SD controls (98% v. 2%, P < 0.001, respectively). Tight junction proteins colocalised at the blood–testis barrier in LD hamsters, but were disorganised within the Sertoli cell cytoplasm in SD animals. FSH treatment restores colocalisation in a time-dependent manner. It is concluded that FSH contributes to the regulation of Sertoli cell proliferation and tight junction formation in the adult Djungarian hamster. This data provides definitive evidence that the adult Sertoli cell population in this model is modifiable by hormones. (1)Meachem et al. (2005). Biol Reprod 72, 1187.(2)Allan et al. (2004). Endocrinol 145, 1587.(3)Russell and Peterson (1985). Int Rev Cytol 94, 177.