Selective effects of benzodiazepines on the acquisition of conditioned taste aversion compared to attenuation of neophobia in C57BL/6 mice.

INTRODUCTION

The effects of pre-conditioning administration of anxiolytic benzodiazepines on the acquisition of a conditioned taste aversion (CTA) and on the acquisition of attenuation of neophobia (AN) were investigated in C57BL/6 mice.

MATERIALS AND METHODS

A CTA was induced by injecting lithium chloride (LiCl; 6 mEq x kg(-1)) 30 min after the animal had imbibed a novel 0.5% saccharin solution. In other animals, neophobia was attenuated by a single access to the novel 0.5% saccharin solution, followed only by injection of saline.

RESULTS AND DISCUSSION

Pre-conditioning administration of chlordiazepoxide (CDZ; 6-24 mg x kg(-1), i.p.) and alprazolam (0.3-1 mg x kg(-1), p.o.) resulted in a CTA that did not differ initially from that observed in vehicle-treated controls, but which showed faster extinction. The acquisition of AN was impaired only after the higher doses of CDZ (12-24 mg x kg(-1), i.p.) or alprazolam (1 mg x kg(-1), i.p.). The results show that in this test, altered acquisition of an aversive CTA memory by anxiolytic benzodiazepines is reflected in more rapid extinction. Moreover, at low doses, these drugs showed selectivity for weakening CTA learning compared to AN learning. Evidence is discussed that selective weakening of aversive memory formation is a clinically relevant effect of anxiolytic benzodiazepines.