NICOTINIC AND MUSCARINIC CHOLINERGIC RECEPTOR-BINDING IN THE HUMAN HIPPOCAMPAL-FORMATION DURING DEVELOPMENT AND AGING

High-affinity nicotine, alpha-bungarotoxin (alpha BT) and muscarinic r eceptor binding was measured in the human hippocampal formation in a s eries of 57 cases aged between 24 weeks gestation and 100 years. Chang es in nicotine receptor binding during development and aging were more striking than differences in alpha BT and muscarinic binding. Nicotin e binding was higher at the late foetal stage than at any other subseq uent time in all areas investigated. In the hippocampus a fall in bind ing then occurred within the first six months of life, with little or no subsequent fall during aging, whereas in the entorhinal cortex and the presubiculum the major loss of nicotine binding occurred after the fourth decade. alpha BT binding was significantly elevated in the CA 1 region, but in no other region of the hippocampus, in the late foetu s, and there was also a fall in alpha BT binding in the entorhinal cor tex during aging from the second decade. The modest changes in total m uscarinic binding, which appeared to reflect those in M1 and M3 + 4 ra ther than M2 binding, were a rise in the entorhinal cortex between the foetal stage and childhood and a tendency for receptors to fall with age in the hippocampus and subicular complex. These findings implicate mechanisms controlling the expression of nicotinic receptors to a gre ater extent than muscarinic receptors in postnatal development and agi ng in the human hippocampus. (C) 1997 Elsevier Science B.V.