Pontine reticular formation is involved in catalepsy produced by cholinergic drugs

Bilateral kainic acid lesions of the ventro-medial (VM) thalamic nucleus of rats which greatly reduced the catalepsy produced by haloperidol (2 mg/kg i.p.) not only did not reduce, but even enhanced, the cataleptogenic effect of eserine (1 mg/kg i.p.) and arecoline (30 mg/kg i.p.). This finding is in accord with former conclusions that catalepsy produced by cholinergic drugs doss not depend on striatal mechanisms. In rats with kainic acid lesions of the VM thalamic nucleus, and similarly in intact, non-lesioned rats, systemic administration of eserine and arecoline potentiated the catalepsy produced by microinjections of carbachol (2 mu g) into the pontine reticular formation (PRF). Atropine microinjected bilaterally into the PRF attenuated the cataleptogenic effect of eserine and arecoline i.p. We suggest that the PRF is a site at which systemically given cholinergic drugs act to produce catalepsy.