Central cholecystokinin octapeptide reduces glucose utilization in subcortical but not cortical rat brain

Cholecystokinin octapeptide was administered intraventricularly to laboratory rats in a behaviorally active dose. Quantitative regional glucose utilization was assessed as a measure of neuronal activity using [¹⁴C]2-deoxyglucose. CCK-8 reduced glucose utilization in selected subcortical nuclei, but left most areas of cortex unaffected. The subcortical nuclei were chiefly extrapyramidal systems. The diminutive pharmacologic action on cortical neuronal activity implies CCK-8 may act here as a neuronal modulator, in concert with other central transmitters, rather than having prominent singular actions.