title: Ontogeny of M1 and M2 muscarinic binding sites in the striatum of the cat: relationships to one another and to striatal compartmentalization.
abstract: The ontogeny of striatal M1 and M2 muscarinic cholinergic binding sites was studied autoradiographically in cats ranging in age from embryonic day 40 to postnatal day six. Direct labeling with [3H]pirenzepine revealed M1 sites, and M2 sites were labeled with [3H]N-methylscopolamine in the presence of pirenzepine. In serial tissue sections, distributions of striatal M1 and M2 sites were compared to one another and to patterns of acetylcholinesterase staining and tyrosine hydroxylase-like immunoreactivity. The younger fetal material demonstrated heterogeneous distributions for both subtypes of muscarinic binding sites, with patches of dense binding corresponding to islands of dopaminergic nigrostriatal innervation. For both M1 and M2 binding, lateral to medial and caudal to rostral density gradients were present in the patches and in the surrounding matrix. During fetal development and into the perinatal period, overall muscarinic binding increased, but more so in the matrix than in the patches. By postnatal day six striatal M2 binding appeared nearly homogeneous. M1 binding, however, was slightly more concentrated in patches than in matrix. The patches of elevated M1 binding were still present at maturity, and corresponded to striosomes. These findings suggest that the ontogenetic regulation of muscarinic binding sites is influenced by location relative to striatal compartments, and that expression of M1 and M2 binding site subtypes is differentially regulated.
authors.affiliation: Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: M A
authors.initials: MA
authors.lastname: Nastuk
authors.forename: A M
authors.initials: AM
authors.lastname: Graybiel
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002415:Cats; D003342:Corpus Striatum / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D005314:Embryonic and Fetal Development; D005865:Gestational Age; D010890:Pirenzepine / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism* / Q000502:physiology; D012601:Scopolamine / Q000378:metabolism
chemical_list: D011976:Receptors, Muscarinic; D010890:Pirenzepine; D012601:Scopolamine