Analysis of muscarinic receptor concentration and subtypes following lesion of rat substantia innominata.
Cholinergic neurones located in the nucleus basalis of Meynert (NBM) in the substantia innominata (SI) of primates are known to project to cerebral cortex and cell loss in NBM is thought to be associated with the cholinergic deficit seen in Alzheimer's disease. We have examined in rats the effect of lesion of SI with kainate (1 microgram/0.5 microliter) on acetylcholine esterase (AChE) activity, muscarinic receptor number and subtypes in cerebral cortex at 1, 2 and 4 weeks. The area of lesion was assessed histologically. AChE activity was significantly reduced in frontal and parietal cortex ipsilateral to the lesion compared to the contralateral side by 37 and 30%, respectively, at 1 week. The reduction in parietal cortex at 4 weeks (16%) was significantly attenuated. Muscarinic receptor number was reduced in cerebral cortex ipsilateral to the lesion at the 3 time periods measured, being reduced by 14 and 17% in the frontal and parietal cortex, respectively, at 1 week. Changes in receptor number and AChE activity correlated with the size of lesion. Low affinity agonist binding sites and high affinity pirenzepine binding sites were also analyzed and found to be significantly reduced by lesion of SI. The proportions of high and low affinity agonist binding sites and subtypes of pirenzepine binding sites were, however, not significantly affected by lesion.
D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D001479:Basal Ganglia / Q000503:physiopathology*; D001665:Binding Sites / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects; D002540:Cerebral Cortex / Q000201:enzymology; D002799:Cholinergic Fibers / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D019832:N-Methylscopolamine; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000032:analysis* / Q000145:classification / Q000187:drug effects; D012602:Scopolamine Derivatives; D013377:Substantia Innominata / Q000503:physiopathology*
D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D000110:Acetylcholinesterase; D007608:Kainic Acid; D019832:N-Methylscopolamine