Effects of isoflurane on the cholinergic system on the hippocampus of aged rats with vascular dementia

Abstract

Objective To investigate the effects of isoflurane at different concentrations on the cholinergic system on the hippocampus of aged rats with vascular dementia(VaD).Methods The model of the old VaD rats was established with the method of 4-vessel occlusion(4-VO) in 60 aged SD rats (30 males and 30 females).The animals were divided into 6 groups according to the days(days 1 and 7)after isoflurane inhalation and the concertrations(0,1.5％ and 2.0％):1 d 0 isoflurane group(Ⅰ 1,0),1 d 1.5％ isoflurane group(Ⅰ 1,5％),1 d 2.0％ isoflurane group(Ⅰ 1,20％),7 d 0 isoflurane group(Ⅰ 7,0),7 d 1.5％ isoflurane group(Ⅰ 7,5％),7 d 2.0％ isoflurane group(Ⅰ 7,2.0％).On day 1 and day 7 after isoflurane inhalation,morris water maze testing was performed.After Morris water maze testing was completed,the aged rats with VaD were killed at once.Then the hippocampus of the aged rats with VaD were dislodged on ice and reserved in icebox at subzero 80 temperature with iquid nitrogen frozening in order to detect the content of acetylcholine,choline acetyltransferase and acetylcholinesterase.The content of acetylcholine in hippocampus is detected by Elisa method,and the content of choline acetyltransferase is detected by kit of choline acetyltransferase and the content of acetylcholinesterase is detected by kit of acetylcholinesterase.Results On the 1st day after isoflurane inhalation,the content of acetylcholine [Ⅰ 1,1.5％(82±10) μg/g and Ⅰ 1.2.0％(65±13) μg/g] and choline acetyltransferase [Ⅰ 1,1.5％(98±11) IU/g and Ⅰ 1,1.20％(81±13) IU/g] in hippocampus were also markedly lower than those of 0 isoflurane group[the content of acetylcholine (99±13) μg/g and the content of choline acetyltransferase (115±11) IU/g] (P＜0.05),of which the 2.0％ isoflurane group had the lowest(P＜0.05).There were not significant different of acetylcholinesterase with different concertrations of isoflurane inhalation (P＞0.05).On the 7th day after isoflurane inhalations,no significant differences were observed the content of acetylcholine[(99±13),(97±13) μg/g and (98±12) μg/g],choline acetyltransferase [(118±12),(128±15) IU/g and (116±15) IU/g] and acetylcholinesterase [(0.71±0.29),(0.70±0.11) U/mgprot and (0.66±0.38) U/mgprot] in hippocampus among three groups (P＞0.05).Conclusions After VaD rats suck in isoflurane,the content of acetylcholine and choline acetyltransferase in the hippocampus were decreased but only temporary,but the contents of acetylcholinesterase was notinfluenced. Key words: Vascular dementia; Old age; Isoflurane; Learning and memory; Acetylcholine; Choline acetyltransferase; Acetylcholinesterase; Hippocampus