title: Muscarinic M1 receptor partially modulates higher sensitivity to cadmium-induced cell death in primary basal forebrain cholinergic neurons: A cholinesterase variants dependent mechanism.
abstract: Cadmium is a toxic compound reported to produce cognitive dysfunctions, though the mechanisms involved are unknown. In a previous work we described how cadmium blocks cholinergic transmission and induces greater cell death in primary cholinergic neurons from the basal forebrain. It also induces cell death in SN56 cholinergic neurons from the basal forebrain through M1R blockage, alterations in the expression of AChE variants and GSK-3β, and an increase in Aβ and total and phosphorylated Tau protein levels. It was observed that the silencing or blockage of M1R altered ChAT activity, GSK-3β, AChE splice variants gene expression, and Aβ and Tau protein formation. Furthermore, AChE-S variants were associated with the same actions modulated by M1R. Accordingly, we hypothesized that cholinergic transmission blockage and higher sensitivity to cadmium-induced cell death of primary basal forebrain cholinergic neurons is mediated by M1R blockage, which triggers this effect through alteration of the expression of AChE variants. To prove this hypothesis, we evaluated, in primary culture from the basal forebrain region, whether M1R silencing induces greater cell death in cholinergic neurons than cadmium does, and whether in SN56 cells M1R mediates the mechanisms described so as to play a part in the cadmium induction of cholinergic transmission blockage and cell death in this cell line through alteration of the expression of AChE variants. Our results prove that M1R silencing by cadmium partially mediates the greater cell death observed on basal forebrain cholinergic neurons. Moreover, all previously described mechanisms for blocking cholinergic transmission and inducing cell death on SN56 cells after cadmium exposure are partially mediated by M1R through the alteration of AChE expression. Thus, our results may explain cognitive dysfunctions observed in cadmium toxicity.
authors.affiliation: Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain. Electronic address: jdelpino@pdi.ucm.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Del Pino
authors.affiliation: Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Zeballos
authors.affiliation: Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Anadon
authors.affiliation: Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Díaz
authors.affiliation: Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Moyano
authors.affiliation: Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain.
authors.forename: Gloria Gómez
authors.initials: GG
authors.lastname: Díaz
authors.affiliation: Department of Pharmacology, Health Sciences School, Alfonso X University, 28691 Madrid, Spain.
authors.forename: Jimena
authors.initials: J
authors.lastname: García
authors.affiliation: Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain.
authors.forename: Margarita
authors.initials: M
authors.lastname: Lobo
authors.affiliation: Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Frejo
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry* / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism; D000818:Animals; D066187:Basal Forebrain / Q000166:cytology*; D002104:Cadmium / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects*; D002795:Choline O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D014644:Genetic Variation; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D010275:Parasympathetic Nervous System / Q000166:cytology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D043643:Receptor, Muscarinic M1 / Q000187:drug effects* / Q000235:genetics; D016875:tau Proteins / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D007527:Isoenzymes; D018727:Muscarinic Antagonists; D043643:Receptor, Muscarinic M1; D016875:tau Proteins; D002104:Cadmium; D002795:Choline O-Acetyltransferase; D000110:Acetylcholinesterase
keywords: Acetylcholine esterase-R; Acetylcholine esterase-S; Basal forebrain neurons; Cadmium; Muscarinic receptor M1; Selective neurotoxicity