Benzodiazepine and muscarinic cholinergic binding sites in striatum and brainstem of the human fetus

The regional distribution of binding sites for [³H]flunitrazepam and $\text{[}{}^3\text{H]N-}\text{methyl-scopolamine}$ was studied in human fetal brain of 18 and 23 weeks gestation by in vitro autoradiography. Areas densely labelled by both ligands include the hypoglossal nucleus and the striatum. The latter is characterized by a patchy distribution of both binding sites reminiscent of acetylcholinesterase staining. Similarities with the rat fetus and the occurrence of binding sites in areas of potential significance for fetal behaviour are discussed.