The effect of ipsapirone on behavioural and cardiac responses in the shock-probe/defensive burying test in male rats

The effects of the 5-HT1A receptor agonist, ipsapirone, on cardiac and behavioural responses of male Wistar rats in a conditioned defensive burying paradigm for anxiolytics were investigated. The shocked rats displayed defensive burying accompanied by an increase in heart rate. Ipsapirone-treated rats (5 and 10 mg/kg i.p.) showed less burying behaviour than did vehicle-treated controls, and the tachycardiac response was also reduced in a dose-dependent way whereas eating behaviour was facilitated. The results demonstrate the effectiveness of ipsapirone, thereby suggesting the involvement of 5-HT1A receptors in a conditioned anxiety situation that elicits an active coping behaviour and sympathetic activation.

Anxiolytics and stress-induced behavioural and cardiac responses: a study of diazepam and ipsapirone (TVX Q 7821)

The present study has been designed to investigate the effects of the 5-HT1A receptor agonist, ipsapirone (TVX Q 7821), a representative of a novel class of anxiolytics, and the classical benzodiazepine anxiolytic, diazepam, on cardiac and behavioural responses in an emotional stress situation. The emotional stress of fear of punishment, induced by training male Wistar rats in an inhibitory avoidance situation, was followed by a bradycardiac response relative to similarly trained, but non-punished, freely moving rats. The behavioural response of stressed rats was immobility in the dark compartment in which an electric footshock (0.6 mA a.c. for 3 s) had been administered as punishment a day earlier. Diazepam administered i.p. in doses of 2.5 mg/kg and 7.5 mg/kg caused a decrease in the interbeat interval (IBI) in shocked and non-shocked rats whereas ipsapirone administered i.p. in doses of 2.5 and 12.5 mg/kg decreased the IBI in shocked rats only. Ipsapirone diminished the duration of immobility in both shocked and non-shocked animals whereas diazepam decreased immobility in shocked rats only. These results suggest a differential effect of the two anxiolytics on the behavioural and cardiac responses to an emotional stress situation. It is suggested that ipsapirone has an anxiolytic-like effect and 'anti-stress' action that is clearly reflected in the cardiac physiology in an anxiety-inducing situation.