The pyrazoloquinoline, CGS 8216, reduces sham feeding in the rat

The pyrazoloquinoline CGS 8216, a benzodiazepine receptor ligand, produced a dose-related (2.5-10.0 mg/kg, IP) attenuation of sham feeding a 30% sucrose solution by rats with open gastric fistulas. Ingestion was reduced by over 50% following the largest dose of CGS 8216 in a 60 min test. The initiation of sham feeding was not delayed by CGS 8216, but sham feeding was subsequently slowed over an extended test period. The suppressant effect of CGS 8216 was reversed by the specific benzodiazepine receptor antagonist Ro15-1788 (20 and 40 mg/kg, IP). Hence the effect of CGS 8216 on sham feeding may be mediated by benzodiazepine receptors, and is consistent therefore with the characterization of CGS 8216 as a benzodiazepine partial inverse agonist. In contrast to sham feeding, CGS 8216 (10.0 mg/kg, IP) did not affect sham drinking in 17 hr water-deprived rats. The results are discussed in relation to possible benzodiazepine receptor involvement in the neurochemical mediation of food palatability.