α1- and α2-Adrenoreceptor antagonists differentially influence locomotor and stereotyped behaviour induced byd-amphetamine and apomorphine in the rat

Publisher Website
Google Scholar
Abstract
The importance of dopamine (DA) in mediating locomotor, exploratory and stereotyped behaviour in rodents is well established. Evidence also indicates a modulatory role for noradrenaline (NA) although, due to non-specificity of previously available agents, a precise role remains undefined. The effects of the specific and selective α-adrenoreceptor antagonists idazoxan (α2) and prazosin (α1) on behaviour induced by amphetamine and apomorphine have been investigated in the rat.d-Amphetamine (2 mg/kg) induced hyperactive locomotion and exploration. Pretreatment with prazosin (1 mg/kg) markedly reduced these responses. In contrast, pretreatment with idazoxan (20 mg/kg) only marginally alteredd-amphetamine hyperactivity. Apomorphine (0.5 mg/kg) induced biphasic locomotor and exploratory activity. Neither α-antagonist affected the initial burst of activity (60 min), although prazosin inhibited whereas idazoxan potentiated the secondary phase (90–180 min). At higher dosage, amphetamine (6 mg/kg) and apomorphine (2 mg/kg) induced stereotyped behaviours. Prazosin pretreatment enhanced stereotyped gnawing and decreased sniffing and locomotion, whereas idazoxan increased locomotion and decreased amphetamine-induced mouth movements. These data indicate that DA-induced locomotor and stereotyped behaviours are differentially influenced (in opposite directions) by both α1- and α2-adrenoreceptor antagonists. NA may thus modulate the expression and character of behaviour by influencing DA function in certain brain areas.

This publication has 32 references indexed in Scilit: