Effects of ifenprodil on isoflurane-induced impairment of learning and memory

Objective To investigate the long-term effects of intracerebroventricular administration of ifenprodil, a N-methyl-D-aspartate receptor subunit 2B(NR2B) receptor antagonist, on isoflurane-induced impairment of learning and memory in mice. Methods Eighty male C57BL/6 mice (8 weeks old) were randomly divided into five groups (n=16): mice in control group (group C) inhaled O2 for 6 h. Those in sham group (group S) inhaled O2 for 6 h after intracerebroventricular injection of 2 μl NS. Those in isoflurane group (group A) inhaled 1.3% isoflurane for 6 h after intracerebroventricular injection of 2 μl NS. Those in isoflurane + ifenprodil group (group AI) inhaled 1.3% isoflurane for 6 h after intracerebroventricular injection of 2 μg ifenprodil (in 2 μl). Those in Ifenprodil group (group I) inhaled O2 for 6 h after intracerebro-ventricular injection of 2 μg ifenprodil (in 2 μl). The learning and memory of the mice 3 d and 7 d after anesthesia was examined by new object recognition (NOR) and contextual fear conditioning test (FC). NR2B mRNA expression in the hippocampus was semi-quantified with quantitative real time polymerase chain reaction(q-PCR). Results Three and seven days after anesthesia, mice in group A showed decreased discrimination index for novel vs. familiar objects, compared with the group S (P 0.05). Conclusions Intracerebroventricular administration of ifenprodil before anaesthesia can decrease isoflurane-induced impairment of learning and memory in mice probably by reducing NR2B expression in the hippocampus.