Search for Nicotine-Like Receptor Binding Sites in Brain. In: Pepeu G, Ladinsky H, editors. Cholinergic Mechanisms. Boston: Springer US; 1981. pp. 639-46. [DOI: 10.1007/978-1-4684-8643-8_63]

A comparison of the regional ontogenesis of nicotine- and muscarine-like binding sites in mouse brain

The postnatal development of the cholinergic neurotransmitter system was studied in the cortex, hippocampus, midbrain and cerebellum of 3-, 7-, 12-, 17- and 30-day-old NMRI mice. The concentration of muscarine-like binding sites determined with [(3)H]quinuclidinyl benzilate as a ligand increased progressively with age. A similar developmental pattern was found for the activity of a presynaptic marker, choline acetyltransferase (ChAT). When expressed as a percentage of the values for 30-day-old mice, however, the muscarine-like receptors were parallel but preceding the development of ChAT in all the brain regions studied. The concentration of nicotine-like binding sites studied with [(3)H]α-bungaro-toxin as a ligand gradually increased with age in the cortex, hippocampus and midbrain, with a peak between days 7 and 12, followed by a decrease towards day 30. With [(3)H]tubocurarine as a ligand, on the other hand, the concentration of nicotine-like binding sites was in general high at 3 days and gradually decreased with age, suggesting that different subpopulations of nicotine-like receptors might be determined when the two ligands are used.

Acetylcholine synthesizing activity and nicotinic binding sites in rat hind limb muscles during reinnervation

Acetylcholine synthesizing (ACh-s) activity and binding of the nicotinic ligands 3H-alpha-bungarotoxin (alpha-Btx) and 3H-d-tubocurarine (d-TC) were analysed in rat hind limb muscles for up to 6 months after a cryolesion of the sciatic nerve. Muscles of the contralateral leg served as controls. After cryolesion there was a rapid decrease in ACh-s activity parallel to a considerable increase in alpha-Btx binding. A clearcut increase in ACh-s activity was first seen at 32 days and complete restoration in ACh-s activity was seen from 2-3 months postoperatively. From the 16th day there was a rapid decrease in alpha-Btx bindings sites and initial values were seen at the 32nd day postoperatively. D-TC binding sites were relatively unchanged during the experimental period. The first neurophysiological signs of reinnervation were seen at 16 days. The rats were observed to move normally about 2 months postoperatively. Normalization of alpha-Btx binding sites seems to be an earlier sign of reinnervation than normalization of ACh-s activity.