MODULATION OF RHYTHMICAL SLOW ACTIVITY, LONG-TERM POTENTIATION AND MEMORY BY MUSCARINIC RECEPTOR AGONISTS

We investigated the cholinergic modulation of hippocampal rhythmical s low activity (or theta activity), long-term potentiation and a behavio ral memory task. The intravenous administration of the muscarinic rece ptor agonists, AF102B s-2-methyl-spiro(1,3-oxathiolane-5,3')quinuclidi ne hydrochloride hemihidrate) and oxotremorine, induced rhythmical slo w activity at doses of 1.0 mg/kg and 0.01 mg/kg, respectively. Long-te rm potentiation of population spike amplitude in the hippocampal CA1, which was induced by tetanic stimulation to the Schaffer collateral/co mmissural fiber, was increased by AF102B (1.0 mg/kg i.v.) and oxotemor ine (0.01 mg/kg i.v.). Oral administration of AF102B and oxotremorine improved scopolamine-induced memory deficits in a passive avoidance ta sk in mice at doses of 1.0 mg/kg and 0.2 mg/kg, respectively. The corr espondence of the effective doses of muscarinic receptor agonists in t hese three experiments suggested the cholinergic correlation of rhythm ical slow activity, long-term potentiation and memory.