CREATINE METABOLISM IN THE SEMINIFEROUS EPITHELIUM OF RATS - II - EFFECT OF MODULATORS OF CELLULAR BIOCHEMICAL FUNCTION ON CREATINE SECRETION BY CULTURED SERTOLI CELLS

The Sertoli cells have been identified as the primary locus for creati ne synthesis within the seminiferous epithelium. The purpose of the st udies reported here was to examine the effect of modulators of Sertoli cell function on creatine secretion by primary cultures of these cell s. Sertoli cell-enriched cultures, maintained in a defined medium, sec reted creatine into the incubation medium in a manner that was linear with time over at least 6 h, but which had reached a plateau within 24 h. Secretion was stimulated by physiological and toxicological modula tors of Sertoli cell function. Incubation of Sertoli cell-enriched cul tures in the presence of FSH (greater than or equal to 40 mU ml(-1)), dibutyryl cyclic AMP (greater than or equal to 0.1 mmol l(-1)), mono-( 2-ethylhexyl) phthalate (greater than or equal to 1 mu mol l(-1)) or c admium (greater than or equal to 3 mu mol l(-1)) increased the secreti on of creatine into the incubation medium by at least 85% over 24 h. C reatine secretion by Sertoli cell-enriched cultures, incubated over 4h in a balanced salt solution, was independent of exogenous L-glutamine . However, the stimulation of secretion induced by I mmol dibutyryl cy clic AMP l(-1) was dependent on the presence of 4 mmol L-glutamine l(- 1) in the incubation medium, which suggests that an increase in creati ne secretion occurs as a consequence of stimulated glutamine oxidation .