Nicotinic acetylcholine receptors in the rat stomach: II. Alterations after vagotomy.

Nicotinic and muscarinic acetylcholine receptors were studied in the stomach of vagotomized rats, with ligand binding techniques, and with the concomitant measurement of choline acetyltransferase (ChAT). The maximum binding capacity (Bmax) of the high affinity sites of (-)-[3H]nicotine binding was significantly increased in all the regions of the stomach of subdiaphragmatically vagotomized animals while the values for the low affinity sites remained the same as those in sham-operated animals. On the other hand, [3H]quinuclidinyl benzilate binding to the stomach was unchanged after vagotomy. ChAT activity was significantly reduced in the vagotomized rats. These results suggest that surgical vagal denervation causes an increase in the density of nicotinic acetylcholine receptors presumably located on the parasympathetic ganglion cells. There is also a reduction of ChAT activity, probably due to a degenerative loss of preganglionic cholinergic neurons. Preganglionic denervation (decentralization) has little influence on the muscarinic receptors of postsynaptic effector organs.