Actions of cholinergic drugs on cells in the interpeduncular nucleus

The muscarinic versus nicotinic effects of acetylcholine (ACh) on the activity of cells in the interpeduncular nucleus (IPN) of guinea pig brain slices were investigated using electrophysiologic techniques. Nicotinic and muscarinic drugs acted postsynaptically to increase the firing rate of cells in the IPN. The excitatory actions of ACh were blocked both by atropine and by d-tubocurarine. These results indicated that cholinergic receptors of IPN cells seem to have both nicotinic and muscarinic characteristics.