Electrophysiological evidence for the presence of receptors for cholecystokinin and bombesin on cultured astrocytes of rat central nervous system.

The action of cholecystokinin (CCK) and bombesin (Bom) was studied on the membrane potential of astrocytes in explant cultures of rat cortex, cerebellum, brain stem and spinal cord. Both peptides (10(-8) and 10(-7) M) caused a hyperpolarization of most astrocytes studied. The hyperpolarization by CCK was markedly reduced or blocked by the CCKB-antagonist L-365,260 whereas addition of the Bom-antagonist [D-Phe12,Leu14]-Bom antagonized the effects of Bom, suggesting a specific action of these peptides. When CCK and Bom were tested on the same cell, both peptides were effective, indicating a colocalization of receptors for CCK and Bom on the glial membrane. Our electrophysiological investigations provide strong evidence for the existence of functional CCK and Bom receptors on astrocytes.