Chapter 5 Mapping of brain nicotinic receptors by autoradiographic techniques and the effect of experimental lesions

Abstract

Publisher Summary This chapter discusses mapping of brain nicotinic receptors by autoradiographic techniques and the effect of experimental lesions. Nicotinic binding sites have been detected using a number of radioligands in in vitro assays of mammalian brain. The most commonly used radioligands are [ 3 H]nicotine, [ 3 H]acetylcholine and 125 I-labelled-α-bungarotoxin. All three bind with high affinity in a saturable and reversible manner, inhibited selectively by nicotinic agents. A much greater degree of neuroanatomical detail can be achieved with receptor autoradiography. High-affinity nicotinic binding sites for [ 3 H]nicotine, [ 3 H]ACh, and to a lesser extent [ 3 H]methylcarbachol have all been mapped autoradiographically in rat brain with virtually identical results. Dense autoradiographic labelling is observed in the medial habenula and interpeduncular nucleus; in the so-called specific motor and sensory nuclei of the thalamus, and in layers III and/or IV of cerebral cortex; in the substantia nigra pars compacts and ventral tegmental area; in the molecular layer of the dentate gyrus and the presubiculum; and in the superficial layers of the superior colliculus. Labelling is conspicuously sparse in the hippocampus and hypothalamus.