The effects of buspirone and diazepam on aversive context- and social isolation-induced ultrasonic vocalisation.

Rats emit two types of high-frequency vocalisations (aversive and appetitive calls) in different behavioural situations. The aims of this paper were to examine an animal model of appetitive behaviour (as an element of social interaction) and to study the effects of selected psychotropic drugs on appetitively evoked ultrasonic vocalisation (USVs) and aversive context-evoked USVs. Specifically, we analysed the impact of the encounter of pairs of adult rats after long-term isolation on ultrasound vocalisation. It was found that isolation of the adult rats significantly enhanced the appetitive ultrasound vocalisations (50-kHz) during encounters between pairs of rats. In the pharmacological part of the study, we found that diazepam (1.0 mg kg(-1)) significantly increased isolation-induced appetitive USVs (50 kHz) and decreased aversive context-evoked USVs (22-kHz). Buspiron (3.0 mg kg(-1)) decreased the aversive context-evoked USVs and had no effect on isolation-induced appetitive USVs. These data indicate that long-term, isolation-induced 50-kHz USVs in adult rats represent a new behavioural parameter under control of the central GABAergic system, which can be used to study the effects of anxiolytic drugs.