title: Activity of muscarinic, galanin and cannabinoid receptors in the prodromal and advanced stages in the triple transgenic mice model of Alzheimer's disease.
abstract: Neurochemical alterations in Alzheimer's disease (AD) include cholinergic neuronal loss in the nucleus basalis of Meynert (nbM) and a decrease in densities of the M2 muscarinic receptor subtype in areas related to learning and memory. Neuromodulators present in the cholinergic pathways, such as neuropeptides and neurolipids, control these cognitive processes and have become targets of research in order to understand and treat the pathophysiological and clinical stages of the disease. This is the case of the endocannabinoid and galaninergic systems, which have been found to be up-regulated in AD, and could therefore have a neuroprotective role. In the present study, the functional coupling of Gi/o protein-coupled receptors to GalR1, and the CB1 receptor subtype for endocannabinoids were analyzed in the 3xTg-AD mice model of AD. In addition, the activity mediated by Gi/o protein-coupled M2/4 muscarinic receptor subtypes was also analyzed in brain areas involved in anxiety and cognition. Thus, male mice were studied at 4 and 15months of age (prodromal and advanced stages, respectively) and compared to age-matched non-transgenic (NTg) mice (adult and old, respectively). In 4-month-old 3xTg-AD mice, the [(35)S]GTPγS binding stimulated by galanin was significantly increased in the hypothalamus, but a decrease of functional M2/4 receptors was observed in the posterior amygdala. The CB1 cannabinoid receptor activity was up-regulated in the anterior thalamus at that age. In 15-month-old 3xTg-AD mice, muscarinic receptor activity was found to be increased in motor cortex, while CB1 activity was decreased in nbM. No changes were found in GalR1-mediated activity at this age. Our results provide further evidence of the relevance of limbic areas in the prodromal stage of AD, the profile of which is characterized by anxiety. The up-regulation of galaninergic and endocannabinoid systems support the hypothesis of their neuroprotective roles, and these are established prior to the onset of clear clinical cognitive symptoms of the disease.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of the Basque Country (UPV/EHU), B° Sarriena s/n, 48940 Leioa, Spain.
authors.forename: Iván
authors.initials: I
authors.lastname: Manuel
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of the Basque Country (UPV/EHU), B° Sarriena s/n, 48940 Leioa, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Lombardero
authors.affiliation: Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA, USA.
authors.forename: Frank M
authors.initials: FM
authors.lastname: LaFerla
authors.affiliation: Institut de Neurosciències & Department of Psychiatry and Forensic Medicine, Faculty of Medicine, Universitat Autònoma de Barcelona, Avgda Can Domènech s/n, 08193 Bellaterra, Spain.
authors.forename: Lydia
authors.initials: L
authors.lastname: Giménez-Llort
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of the Basque Country (UPV/EHU), B° Sarriena s/n, 48940 Leioa, Spain. Electronic address: rafael.rodriguez@ehu.es.
authors.forename: Rafael
authors.initials: R
authors.lastname: Rodríguez-Puertas
mesh_terms: D000375:Aging / Q000187:drug effects / Q000378:metabolism / Q000523:psychology; D000544:Alzheimer Disease / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D004195:Disease Models, Animal; D018450:Disease Progression; D019004:Galanin / Q000494:pharmacology; D006801:Humans; D008297:Male; D008822:Mice, Transgenic; D018377:Neurotransmitter Agents / Q000494:pharmacology; D062706:Prodromal Symptoms; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism*; D044091:Receptor, Galanin, Type 1 / Q000378:metabolism*; D043585:Receptor, Muscarinic M2 / Q000378:metabolism*; D043588:Receptor, Muscarinic M4 / Q000378:metabolism*; D012720:Severity of Illness Index
chemical_list: C578453:CNR1 protein, mouse; D018377:Neurotransmitter Agents; D043884:Receptor, Cannabinoid, CB1; D044091:Receptor, Galanin, Type 1; D043585:Receptor, Muscarinic M2; D043588:Receptor, Muscarinic M4; D019004:Galanin; D002217:Carbachol
keywords: Alzheimer; G protein; autoradiography; cholinergic; neurolipids; neuropeptides