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 is preceded by alterations in the assembly characteristics of tubulin isolated from exposed rat testes. This is followed by decreased seminiferous tubule fluid (STF) secretion by Sertoli cells and an increase in the number and size of Sertoli cell vacuoles. The possible involvement of microtubules and microtubule motor-dependent transport processes in STF secretion by Sertoli cells prompted us to examine the immunodistribution of the microtubule motors cytoplasmic dynein and kinesin during and after 2,5-HD exposure in rats. Three weeks following the commencement of exposure (1% 2,5-HD in the drinking water), the intensity of apical Sertoli cell cytoplasmic dynein immunofluorescence declined. This staining deficit became statistically significant by 4 weeks of exposure. Accompanying this change, there was progressive disruption of the immunodistribution of cisternal Golgi elements and associated kinesin immunoreactivity. The decrease in apical Sertoli cell cytoplasmic dynein immunofluorescence and disruption of Golgi and kinesin immunoreactivity suggest that 2,5-HD-induced alterations in Sertoli cell-mediated transport and secretory events could involve deficits in microtubule-dependent motor function.