ABSTRACT
The anxiolytic benzodiazepines, chlordiazepoxide and midazolam, block the corticosterone and prolactin but not the renin response to stress (Van de Kar et al., 1985a). In contrast, the non–benzodiazepine anxiolytic 5HT–1A agonist, buspirone, attenuates the corticosterone, prolactin and renin responses to conditioned fear (Van de Kar et al., 1985b; Urban et al., 1986). High doses of buspirone and ipsapirone, however, elevate plasma corticosterone and renin concentrations in non–stressed male rats (Urban et al., 1986; Lorens & Van de Kar, 1987). These observations suggest that distinct types of anxiolytic drugs differentially affect the endocrine responses to stress. In the present study we examined the dose–dependent effects of the putative anxiolytic 5HT–1A agonist, ipsapirone, on the behavioural, endocrine and neurochemical responses to conditioned fear.
