RESUMO
Objective:To preliminarily investigate the relationship between the mechanism of sevoflurane-induced cerebral neurotoxicity and receptors of 5-HT 1A and 5-HT 3 in aged rats. Methods:Twenty-four clean-grade healthy male Sprague-Dawley rats, aged 18-20 months, weighing 600-750 g, were divided into 3 groups ( n=8 each) using a random number table method: group C, group LS and group HS.In group C, group LS and group HS, 50% O 2, 1.5% sevoflurane plus 50% O 2 and 3% sevoflurane plus 50% O 2 were inhaled for 2 h, respectively.Open field test was performed at 1 day before inhalation of sevoflurane and at 1 day after the end of inhalation, the time spent in the central square, the number of crossing the grid and the number of standing on the back legs were recorded.The Morris water maze test was performed at 6 days before inhalation of sevoflurane and at 1 day after the end of inhalation, the escape latency, the total swimming distance and the number of crossing the platform were recorded.Immediately after the end of behavioral testing, the hippocampal tissues were obtained for determination of 5-HT 1A and 5-HT 3 receptors mRNA expression and the number of positive cells (using real-time reverse transcription-polymerase chain reaction assay and immunohistochemical method). Results:Compared with group C, the time spent in the central square was significantly prolonged, the number of crossing the grid and the number of standing on the back legs were decreased, the escape latency was prolonged, the total swimming distance was increased, the number of crossing platform was decreased, the mRNA expression of 5-HT 1A and 5-HT 3 was down-regulated, and the number of positive cells was decreased in HS group ( P<0.05). Conclusion:The mechanism of cerebral neurotoxicity induced by sevoflurane may be related to the down-regulation of the activities of 5-HT 1A and 5-HT 3 receptors in aged rats.
RESUMO
Objective To study the changes of intestinal transit rate, quantity of enterochromaffin cells and expressions of 5-hydroxytryptamine receptor 3 (5-HT3R) in SD rats at different ages, and to investigate the possible mechanism of gastrointestinal dysfunction in aged rats. Methods Eighty healthy SD rats were divided into five groups: three months age, nine months age, eighteen months age, twenty-four months age and thirty months age,and there were sixteen rats in each group. The intestinal transit rate was detected. Immunohistochemistry staining was used to test the quality of chromaffin cells in mucosa and submucosa of jejunum, ileum and colon and to detect the expressions of 5-HT3R in intestinal myenteric plexus. Results The intestinal transit rate was significantly lower in thirty months age group than in three months age group [(52.1±9.8)% vs. (67.2±13.5)%, t=7.013, P=0.001]. In thirty months age group, the quality of chromaffin cells in mucosa and submueosa of jejunum, ileum and colon were 11.1±3.0, 10.6±1.9, 10.2±4.3, respectively, which were reduced compared with three months age group (22.9±6.2, 25.8±7.1, 23.0±5.7, t=3. 640,3. 384,4. 154, all P<0.01). The expressions of 5-HT3R in myenteric plexus of jejunum and ileum were reduced in thirty months age group than in nine months age group [4.8±1.4, 9.3±4.2 vs. 8.9±1.5, 14.5±5.3;t=3.464, 3.003,all P<0.01]. The expression of 5-HT3R in colon myenteric plexus were 5.0±1.3 and 9.0±1.7 in thirty months age group and three months age group, respectively (t=4.549,P<0.001). Conclusions In aged rats, the intestinal transit rate, quantity of enterochromaffin cells and expressions of 5-HT3R are decreased with ageing, and the gastrointestinal dysfunction may be associated with the changing of the quantity of enterochromaffin cells and expressions of 5-HT3R in myenteric plexus.