title: The missing link between long-term stimulation of nicotinic receptors and the increases of acetylcholine release and vasodilation in the cerebral cortex of aged rats.
abstract: In adult rats (4-9 months), chronic nicotine infusion increases the basal level of acetylcholine (ACh) release in the cerebral cortex and enhances responses of cortical ACh release and cortical vasodilation elicited by nucleus basalis of Meynert (NBM) stimulation. In the present study, we examined whether these effects of nicotine are detected in aged rats. Aged rats (27-30 months) received sustained subcutaneous nicotine (100 μg/kg/h) or saline for 14 days. Under urethane anesthesia, ACh release and regional blood flow in the parietal cortex were measured. The basal level of ACh release in the cerebral cortex was not changed by chronic nicotine. In addition, the magnitudes of ACh release and vasodilation by NBM stimulation were similar between the saline-treated and nicotine-treated groups. The lack of an effect of chronic nicotine in aged rats may be due to a decrease in nicotinic receptors in the cerebral cortex during aging (Nordberg et al., J Neurosci Res 31:103-111, 1992).
authors.affiliation: Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan. suchida@tmig.or.jp
authors.forename: Sae
authors.initials: S
authors.lastname: Uchida
authors.forename: Harumi
authors.initials: H
authors.lastname: Hotta
authors.forename: Hidemi
authors.initials: H
authors.lastname: Misawa
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kawashima
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000818:Animals; D020532:Basal Nucleus of Meynert / Q000502:physiology; D001783:Blood Flow Velocity / Q000187:drug effects; D002540:Cerebral Cortex / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004558:Electric Stimulation; D005260:Female; D055104:Infusions, Subcutaneous; D008297:Male; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D009538:Nicotine; D000109:Acetylcholine