| Objective To investigate the effect and mechanism of GABAB receptor in insular cortex in recognition memory by observing the effects of GABAB receptor expression on spatial recognition memory and detecting the expression of CREB in insular cortex.Material and Methods SPF male SD rats weighting 200-240 g,were provided by the Experimental Animal Center of Ningxia Medical University,reared in a quiet environment in the natural cycle of day and night.Rats were randomly divided into five groups: Group blank,Group Baclofen,Group CGP,Group Sham operation and Group Normal saline,n=12 in each group.(1)Group blank received no processing;(2)Group Baclofen was implanted bilaterally with stainless steel guide cannula and injected BLF before the daily test.(3)Group CGP was implanted bilaterally with stainless steel guide cannula and injected CGP before the daily test.(4)Group Sham operation was implanted bilaterally with stainless steel guide cannula only.(5)Group Normal saline was implanted bilaterally with stainless steel guide cannula and injected NS before the daily test.Two weeks later,tests of spatial memory were performed.Microinjection was performed bilaterally before the daily test.The spatial memory of the rats was observed by Intellicage.After the behavioral experiment,some rats were decapitated,stripped of insular tissue cryopreservation;another rats in vivo perfusion line embedded in frozen section.Nissl's staining was used to verify the target.Immunohistochemistry and western-blotting was used for quantitative detection of CREB in insular.Experimental data expressed as mean±standard deviation,data using single-factor analysis of variance between groups after the homogeneity of variance test was used to compare the difference was statistically significant LSD-t test,with p<0.05 was considered statistically significant.Result(1)Behavioral test:Nose-poke learning test showed rats successfully drink times of Group blank,Group Baclofen,Group CGP,Group Sham operation and Group Normal saline were 16.7±3.7,3.6±1.4,10.1±2.8,15.7±2.3,15.9±2.8,the differences of drinking times between Group Baclofen,Group CGP and Group blank were statistically significant(p<0.05).Place learning test showed rats correct times of Group blank,Group Baclofen,Group CGP,Group Sham operation and Group Normal saline were 20.5±5.5,3.5±2.3,12.7±6.1,19.3±6.1,19.1 ±5.5,Place reversal learning test correct times were 20.9±7.0,5.2± 2.8,13.0 ± 5.2,19.4±6.3,18.7±4.3,The differences of correct times between Group Baclofen,Group CGP and Group blank were statistically significant(p<0.05).LED corner visiting times were 9.8±6.4,6.9± 4.9,7.6±4.7,12.9±7.7,8.9±6.5.The differences of LED corner visiting times among all groups were not significant(p>0.05).(2)Immunohistochemistry: If the neuronal cytoplasm showed tan,it is positive.The positive cell's numbers of the expression of CREB in Group blank,Group Baclofen,Group CGP,Group Sham operation and Group Normal saline were 36.4±3.8,26.0±9.7,63.2±8.7,38.6±5.9,41.0±6.6.The differences of the expression of CREB between Group Baclofen,Group CGP and Group blank were statistically significant(p<0.05).The expression of CREB in Group Baclofen was significantly lower(P<0.01).There is no statistical significance between Group blank,Group Sham operation and Group Normal saline(P>0.05).(3)Western-bloting:Using Gel-Pro analyzer Gel imaging analysis software to calculate each groups' relative grey value.The relative expression of CREB in Group blank,Group Baclofen,Group CGP,Group Sham operation and Group Normal saline were: 1.00±0.11,0.53±0.10,1.61±0.12,0.98±0.09,0.99±0.10.The differences of the expression of CREB between Group Baclofen,Group CGP and Group blank were statistically significant(p<0.05).Conclusion The change of expression of GABAB receptor in insular has an significantly effect on rats' spatial exploration ability,and both too high and too low level damage the spatial recognition memory of rats.The expression of CREB play an important role in this process. |
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