title: Old-onset caloric restriction effects on neuropeptide Y- and somatostatin-containing neurons and on cholinergic varicosities in the rat hippocampal formation.
abstract: Caloric restriction is able to delay age-related neurodegenerative diseases and cognitive impairment. In this study, we analyzed the effects of old-onset caloric restriction that started at 18 months of age, in the number of neuropeptide Y (NPY)- and somatostatin (SS)-containing neurons of the hippocampal formation. Knowing that these neuropeptidergic systems seem to be dependent of the cholinergic system, we also analyzed the number of cholinergic varicosities. Animals with 6 months of age (adult controls) and with 18 months of age were used. The animals aged 18 months were randomly assigned to controls or to caloric-restricted groups. Adult and old control rats were maintained in the ad libitum regimen during 6 months. Caloric-restricted rats were fed, during 6 months, with 60 % of the amount of food consumed by controls. We found that aging induced a reduction of the total number of NPY- and SS-positive neurons in the hippocampal formation accompanied by a decrease of the cholinergic varicosities. Conversely, the 24-month-old-onset caloric-restricted animals maintained the number of those peptidergic neurons and the density of the cholinergic varicosities similar to the 12-month control rats. These results suggest that the aging-associated reduction of these neuropeptide-expressing neurons is not due to neuronal loss and may be dependent of the cholinergic system. More importantly, caloric restriction has beneficial effects in the NPY- and SS-expressing neurons and in the cholinergic system, even when applied in old age.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319, Porto, Portugal, cardosoa@med.up.pt.
authors.forename: Armando
authors.initials: A
authors.lastname: Cardoso
authors.forename: Diogo
authors.initials: D
authors.lastname: Silva
authors.forename: Sara
authors.initials: S
authors.lastname: Magano
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Pereira
authors.forename: José P
authors.initials: JP
authors.lastname: Andrade
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000375:Aging / Q000378:metabolism / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D031204:Caloric Restriction / Q000379:methods*; D002452:Cell Count; D002799:Cholinergic Fibers / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D023421:Models, Animal; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009478:Neuropeptide Y / Q000378:metabolism*; D010784:Photomicrography / Q000379:methods; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012680:Sensitivity and Specificity; D013004:Somatostatin / Q000378:metabolism*; D016610:Tissue Embedding
chemical_list: D015415:Biomarkers; D009478:Neuropeptide Y; D013004:Somatostatin; D000109:Acetylcholine