NORADRENALINE AND POTENTIATION IN THE CHICK BRAIN SLICE

THE role of the noradrenergic system as a modulator of neurotransmissi on in the chick forebrain was investigated in brain slices containing the medial hyperstriatum ventrale, an area known to be involved in lea rning and memory. The alpha(2)-agonist clonidine (20 mu M) decreased t he post-synaptic response to local stimulation at 0.1 Hz, while activa tion of, beta(2) receptors increased this response. Induction of persi stent potentiation following stimulation at 5Hz was blocked by drugs ( 20 mu M ICI 118,551; 20 mu M propranolol) which showed preferential an tagonistic activity at the beta(2) receptor but not by the beta(1)-pre ferential antagonist timolol. This effect may be due to an interaction with the NMDA receptor system.