| Objective To investigate the possible influence of the isoflurane on the cognitive function and the astroglia GFAP expression in aged rats.Mehtod Sixty-nine SD female rats, aged between 22 and 24 months, were divided randomly into 3 groups: control group(group A, n=21), group 1.2% isoflurane(group B, n=24) and group 1.8% isoflurane (group C, n=24). The rats in the control group only inhaled mixed gas containing 40% oxygen for 3 hours. The rats in the anesthesia groups, including group B and group C, were induced by inhalation of 3% isoflurane, after their body-righting reflex disappeared, then inhaled 1.2%(group B) and 1.8%(group C) isoflurane to maintain anesthesia for 3 hours, respectively. During the course of anesthesia, we kept the concentration of 40% oxygen, and randomly took 3 rats for monitoring their vital signs. Let the rats wake up spontaneously after anesthesia.Cognitive function was assessed using Morris water maze test from 24 hours after anesthesia. The time of observation consists of place navigation test for 6 consecutive days and spatial probe test at 7th day afer anesthesia, mean escape latency and spatial probe time were recorded.Three rats were randomly selected from each group at 1st,3rd 7th day afer stopping oxygen or isoflurane inhalation, respectively. Their brains were taken, coronary slice were prepared. The tissue were immunohistochemically stained, and the astrocytic population was studied by means of anti-GFAP staining.Results①Ethology test:The rats' mean escape latency of the anesthesia group were longer than that of the control group at 2ndday(44.16±17.91s,47.41±20.94s,23.61±13.91s for B,C,A group, respectively,P<0.01) and 3rd day(26.80±11.51s,27.08±11.64s,14.87±8.37s for B,C,A group, respectively,P<0.05), but there was no significant difference between group B and group C(P>0.05); there also was no significant difference at other observation days(P>0.05).②Morphological expression: The astroglia GFAP in the hippocampus were expressed obviously, the GFAP-positive astrocytes of the control group with bigger cell body, thicker and longer processes, and were stained deeper in comparison with the astrocytes of both anesthesia groups during the days of observation. The number of GFAP-positive astrocytes in the anesthesia group were less than the control group, especially on the 3rd day after anesthesia, with smaller cell body, thinner and shorter processes, stained more lighter; there was no significant differernce between the two anesthesia groups on morphology.Conclusion Isoflurane anesthesia could result in cognitive impairment in the aged rats for a short time, and restrain the expression of the GFAP in astrocytes. |
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