2,5-HEXANEDIONE EXPOSURE ALTERS MICROTUBULE MOTOR DISTRIBUTION IN ADULT-RAT TESTIS

2,5-Hexanedione (2,5-HD) exposure in rats causes a progressive Sertoli cell injury culminating in testicular atrophy. Morphological injury i s preceded by alterations in the assembly characteristics of tubulin i solated from exposed rat testes. This is followed by decreased seminif erous tubule fluid (STF) secretion by Sertoli cells and an increase in the number and size of Sertoli cell vacuoles. The possible involvemen t of microtubules and microtubule motor-dependent transport processes in STF secretion by Sertoli cells prompted us to examine the immunodis tribution of the microtubule motors cytoplasmic dynein and kinesin dur ing and after 2,5-HD exposure in rats. Three weeks following the comme ncement of exposure (1% 2,5-HD in the drinking water), the intensity o f apical Sertoli cell cytoplasmic dynein immunofluorescence declined. This staining deficit became statistically significant by 4 weeks of e xposure. Accompanying this change, there was progressive disruption of the immunodistribution of cisternal Golgi elements and associated kin esin immunoreactivity. The decrease in apical Sertoli cell cytoplasmic dynein immunofluorescence and disruption of Golgi and kinesin immunor eactivity suggest that 2,5-HD-induced alterations in Sertoli cell-medi ated transport and secretory events could involve deficits in microtub ule-dependent motor function. (C) 1995 Society of Toxicology.