Inferior olivary lesions after local injections of 3-acetylpyridine in rabbits.

This report presents evidence that local injections of 3-acetylpyridine (3-AP) produce circumscribed lesions of the inferior olive (IO) in rabbits. These restricted lesions, assessed in both cresyl violet-stained sections after a 14-day survival and cupric-silver-stained sections after a 16-24 h survival period, are similar in appearance to lesions produced by systemic 3-AP administration in rats. Two types of degeneration are observed: destruction of cells at the injection site and more diffuse cell death in the ipsilateral and contralateral inferior olive. The latter type of degeneration appears to result from IO fiber-of-passage uptake of 3-AP. There was no evidence of lesions in surrounding structures or in sources of axons passing through periolivary regions. Thus, this protocol is a promising tool for studies of climbing fiber connectivity and physiology in rabbits.