Some aspects on the anatomy and function of central cholecystokinin systems

The distribution of some cholecystokinin (CCK) systems in the rat brain is reviewed focusing (in mesencephalic dopamine neurones which coexpress CCK and, in particular, on cortico-striatal CCK neurones which probably have glutamate as their co-transmitter. Functional studies based on the effect of several CCKB antagonists on phenecyclidine-induced motility suggest that CCK is involved in locomotor behaviour causing inhibition in phencylidine-treated habituated rats. In contrast, in unhabituated rats CCK stimulates exploratory behaviour. These effects may he related to the cortico-striatal CCK/glutamatergic pathway Moreover, these studies provide evidence for endogenous release of a neuropeptide with behavioural consequences.