Angiotensin II Delays The Extinction of Active Avoidance in Rats The Role of Transmitter Receptors

G. Telegdy, T.Kambourova, V. Georgiev

The extinction of active avoidance behaviour in rats following the intracerebroventricular (ICV) injection of different doses of angiotensin II (Ang II) was studied. The influence of antagonists of different neurotransmitter receptors on the effects of Ang II was also followed. Ang II induced a delay in the extinction in a dose-dependent fashion (U-shaped curve). When the animals were pretreated with different receptor blockers in doses which themselves had no action on the extinction of active avoidance behaviour, the action of Ang II on this paradigm was completely blocked by saralasin, haloperidol, bicuculline, atropine, naloxone Phenoxybenzamine, propanolol and methysergide were ineffective. The data suggest that Ang II delays the extinction of active avoidance behaviour, and that angiotensin, dopamine, GABAa, opiate might be involved in this action.