THE EFFECTS OF ALPRAZOLAM ON SUPPRESSED AND NON-SUPPRESSED RESPONDING, ALONE AND IN COMBINATION WITH RO 15-1788, YOHIMBINE, QUIPAZINE, AND CARBACOL, IN THE RAT

Abstract

The effects of alprazolam (ALPZ), Ro 15-1788 (Ro), yohimbine (YHB), quipazine (QP), and carbacol (CBL) were studied on suppressed and non-suppressed VI-60 second responding in rats. ALPZ (.3-10mg/kg,i.p.) increased both suppressed and non-suppressed responding, at 5.6 mg/kg. Ro (1-3mg/kg), YHB (1-10mg/kg), QP (0.01-1mg/kg), and CBL (0.03-.1mg/kg) only decreased suppressed responding over the range of doses studied but increased non-suppressed responding at the lower doses. YHB attenuated the rate-increasing effect of ALPZ on suppressed responding to the largest extent, with Ro, CBL, QP attenuating the effect of ALPZ less, respectively. For non-suppressed responding the rate-increasing effects of ALPZ were attenuated to the largest extent by YHB, and to decreasingly lesser extents, by CBL, QP, and Ro, respectively. These results suggest that the pharmacological intervention of the rate-Increasing effects of ALPZ on suppressed and non-suppressed responding can result in different neuropharmacological profiles, suggesting that each may depend on different mechanisms to varying degrees. Considering the differences in effect of each agent on the rate-increasing effect on suppressed and non-suppressed responding, the anxiolytic effect of ALPZ seemed best related to GABAergic mechanisms while the 5HT, cholinergic, and noradrenergic antagonism of the rate-increasing effect of ALPZ seemed less specific to suppressed responding.