INTERACTION BETWEEN THE ALPHA-2-NORADRENERGIC AND MUSCARINIC SYSTEMS IN THE REGULATION OF NEOCORTICAL HIGH-VOLTAGE SPINDLES

The present experiments were carried out in order to study the interaction between alpha2-noradrenergic and muscarinic systems in regulating high voltage spindle (HVS) activity in neocortex. Alpha2-antagonist (atipamezole 1 and 10 mg/kg) blocked HVS activity. Atipamezole at 0.1 mg/kg dose had no effect on HVS activity. Alpha2-agonist (guanfacine 0.004, 0.02 and 0.1 mg/kg) increased dose dependently HVSs. Guanfacine-induced HVSs were blocked by nucleus reticularis (NRT) lesions and by stimulation of either noradrenergic or cholinergic (pilocarpine) systems. Moreover, combined injections of atipamezole 1 mg/kg and pilocarpine 3 mg blocked HVSs more effectively than either of the drugs alone. Our results suggest that the NRT is jointly modulated by the noradrenergic and cholinergic afferents. © 1990.