title: Chronic cerebral hypoperfusion disrupts discriminative behavior in acquired-learning rats.
abstract: We describe an 'acquired-learning' rat model that was used to investigate the effects of chronic cerebral hypoperfusion on the maintenance of previously acquired discriminative behavior using the discriminating learning task. Male Wistar rats, aged 11 weeks, were trained to discriminate between lamp-on and lamp-off states under an operant-type learning procedure. After 30 sessions, we selected 'acquired-learning' rats with an average discrimination ratio higher than 75% recorded during the last three sessions. Chronic hypoperfusion was then induced by permanent ligation of both common carotid arteries under pentobarbital anesthesia. The rats were tested after surgery over a period of 12 weeks and brain tissue was analyzed for muscarinic acetylcholine receptor (mACh-R) binding. Cerebral hypoperfusion resulted in a significant reduction in the discrimination ratio throughout the observation period, compared with sham-operated rats. However, chronic hypoperfusion would not affect on motor function. The maximum number of mACh-R examined 12 weeks after the operation was significantly reduced in the frontal cortex and hippocampus in the hypoperfusion group. Impaired discrimination learning was associated with a reduction in mACh-R. Our findings suggest that chronic cerebral hypoperfusion in acquired-learning rats is a useful model for investigating the pathophysiology of dementia and that cortical and/or hippocampal cholinergic systems contributes to learning impairment, at least, in our learning task.
authors.affiliation: Department of Physiology, Saitama Medical School, Moroyama, Japan. kntanaka@saitama-med.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: N
authors.initials: N
authors.lastname: Wada
authors.forename: K
authors.initials: K
authors.lastname: Hori
authors.forename: M
authors.initials: M
authors.lastname: Asanuma
authors.forename: M
authors.initials: M
authors.lastname: Nomura
authors.forename: N
authors.initials: N
authors.lastname: Ogawa
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002545:Brain Ischemia / Q000503:physiopathology* / Q000523:psychology; D017536:Carotid Artery, Common / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology*; D008297:Male; D009928:Organ Specificity; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012016:Reference Values; D013997:Time Factors
chemical_list: D011976:Receptors, Muscarinic