CCK modulation of cerebellar afferents: dopaminergic involvement

1. Dopamine agonists and dopamine releasers act at the level of the striatum to activate a mossy fiber pathway which in turn increases cerebellar cGMP in the rodent. 2. CCK acts to both decrease basal cerebellar cGMP levels as well as to antagonize increases in cerebellar cGMP elicited by dopaminergic agonists and releasers. 3. This CCK action involves a "central-type" CCK receptor population which resides outside of the cerebellum. 4. These data are consistent with the pharmacology for CCK inhibition of dopamine release in the striatum; suggesting that CCK effects on cerebellar cGMP may be mediated by antidopaminergic actions within this striatum.