Changes in GABA content and turnover in discrete regions of rat brain after systemic administration of caerulein.

The effects of systemically injected caerulein, a cholecystokinin octapeptide analogue, on GABA content and turnover have been studied in various regions of rat brain. Caerulein decreased GABA levels in the nucleus accumbens, tuberculum olfactorium and substantia nigra and diminished GABA turnover rates in the striatum, nucleus accumbens and substantia nigra, as estimated from the rate of GABA accumulation after inhibition of GABA transaminase by aminooxyacetic acid (AOAA). These results indicate the effect of caerulein on the utilization of GABA in specific cerebral regions and suggest that the GABAergic system is involved in the mechanism of action of peripherally administered caerulein.