Cholecystokinin neuron systems and their interactions with the presynaptic features of the dopamine neuron systems. A morphometric and neurochemical analysis involving studies on the action of cholecystokinin-8 and cholecystokinin-58.

A unique role for CCK-58 compared to that for CCK-8 has been demonstrated in the modulation of central catecholaminergic mechanisms and neuroendocrine functions. It is of paramount importance to localize CCK-58 immunoreactivity within the brain in order to establish if separate CCK-58- and CCK-8-immunoreactive neuron systems exist. The two most significant actions of CCK-58 are a marked lowering of TSH secretion and a selective increase of DA turnover in DA-CCK co-existing synapses in the nucleus accumbens and tuberculum olfactorium.