Baclofen and cerebellar cyclic GMP levels in mice.

Baclofen (3.5--10.0 mg/kg) dose dependently decreased cerebellar cyclic GMP content in mice correlated to a reduction in locomotor activity. Pretreatment with baclofen antagonized the rise in cerebellar cyclic GMP content induced by isoniazid and picrotoxin, but did not affect the increase in cyclic GMP following administration of pentetrazole. Baclofen had little effect on the arecoline-induced changes in cerebellar cyclic GMP content. Therefore, our data support the concept of gamma-aminobutyric acid agonistic properties of baclofen at presynaptic sites.