Rat testis during 2,5-hexanedione intoxication and recovery. II. Dynamics of pyrrole reactivity, tubulin content, and microtubule assembly.

Charles River CD rats (200 g) were intoxicated with 1% 2,5-hexanedione (2,5-HD) in the drinking water for 5 weeks followed by a 17-week recovery period. Pyrrole reactivity of testis proteins increased early during intoxication and then returned toward normal during recovery. Testis tubulin content first increased as germ cells were lost and then fell over time while atrophy was maintained. Purified testis tubulin demonstrated a decreased nucleation time for microtubule assembly at 2 weeks, maintained this alteration throughout intoxication, and then returned to normal assembly kinetics during recovery. The assembly abnormality was accompanied by the presence of a unique crosslinked tubulin species. These findings support the hypothesis that alterations in Sertoli cell microtubules result in germ cell loss following 2,5-HD exposure.