NEURONAL RESPONSES TO DELTA(9)-TETRAHYDROCANNABINOL IN THE SOLITARY TRACT NUCLEUS

The effects of Delta(9)-tetrahydrocannabinol on single-unit activity i n the subpostremal division of the nucleus tractus solitarii were inve stigated by extracellular recording in rat brain slices. The spontaneo us firing rate of 54.8% of the recorded neurons was significantly chan ged after bath applications of Delta(9)-tetrahydrocannabinol. Putative nutrition-related neurons responding to a moderate increase in glucos e concentration were selectively sensitive to Delta(9)-tetrahydrocanna binol. The Delta(9)-tetrahydrocannabinol-sensitive neurons were depres sed by clonidine and are therefore likely to be adrenergic or noradren ergic. These observations suggest that some catecholaminergic, glucose -responsive neurons in the subpostremal nucleus tractus solitarii migh t mediate the influence of cannabinoids on feeding behaviour. Furtherm ore, mo st Delta(9)-tetrahydrocannabinol-sensitive neurons in the nucl eus tractus solitarii showed opposite responses to Delta(9)-tetrahydro cannabinol and the 5-HT3 receptor agonist 1-phenylbiguanide, and might therefore be involved in the nausea-reducing effects of cannabinoids.