Effects of enriched environment on sevoflurane-induced PV interneuronsphenotypic loss and long-term cognitive dysfunction in neonatal rats / 临床麻醉学杂志

ABSTRACT

Objective To investigate the expression of parvalbumin (PV)in the cognitive im-pairment mice induced by sevoflurane anesthesia,and to explore whether enriched environment could reverse it.Methods One hundred and forty-four Six-day-old C57BL/6 male mice at postnatal day 6 were randomly divided into the following four groups (n =36)control+standard environment group (group CS),control+enriched environment group(group CE),sevoflurane anesthesia+standard en-vironment group(group SS)and sevoflurane anesthesia+enriched environment group(group SE).An-imals were exposed to 3% sevoflurane plus 30% O 2 or 30% O 2 2 h daily for 3 days from postnatal day 6 (P6)to P8.The exposed pups were randomly allocated to an enriched environment for 2 h daily between P8 and P90 or to a standard environment.Western blotting were used for determining PV ex-pression in the prefrontal cortex and hippocampus at P9,P14,P42,P60 and P90.Cognitive functions were assessed by performing the open field (P41 ),and fear conditioning tests (P42-43 and P89-90, respectively).Results In the open field test,there was no significant difference in the total travel dis-tance and the time spent in the center of the arena among groups.In the contextual fear condition test, compared with group CS,the group SS only exhibited a reduced freezing response in the contextual test at P43,but not at P90.In the cued fear conditioning test,no difference was observed in the freez-ing time among the four groups.The PV expression in the prefrontal cortex and hippocampus of group SS were significantly lower than that of group CS at P9 and P14 (P <0.001),while recovered at P60 and P90.The PV expression in the prefrontal cortex and hippocampus of group SE were significantly higher than that of group SS at P42 (P <0.05).Linear regression analysis demonstrated a positive correlation between the PV expression in the prefrontal cortex and the freezing time induced by envi-ronment (r =0.670 7,P =0.000 1),and there was a positive correlation between the PV expression in hippocampus and the freezing time induced by environment (r = 0.509 6,P = 0.001 9 ). Conclusion The cognitive impairment induced by sevoflurane anesthesia may be associated with the reduction of PV in the prefrontal cortex and hippocampus.Placement of the sevoflurane-exposed mice in an enriched environment prevented the development of these abnormalities.