Effects of RO20-1724 on cognitive function in immature rats after ketamine anesthesia

Objective To investigate the effect of RO20-1724 on the cognitive function in immature rats after ketamine anesthesia.Methods Ninety-six SD rats of both sexes,aged 21 days,weighing 45-55 kg,were randomly divided into 8 groups ( n =12 each):control group (group C) ; ketamine group (group K) ; ketamine + normal saline group (group K + N) ; ketamine + anhydrous alcohol group (group K + A) ; ketamine + 4 different doses of RO20-1724 groups (group K + R1-4 ).The rats were anesthetized with intraperitoneal injection of kctamine 70 mg/kg in groups K,K+N,K+A and K+.R1-4.Normal saline 2 ml,anhydrous alcohol (in normal saline 2 ml),and RO20-1724 0.25,0.50,0.75 and 1.00 mg/kg (in anhydrous alcohol 8 μl and then in normal saline 2 ml) were injected intraperitoneally in groups K + N,K + A and K + R1-4 respectively 30 min later.Six rats from each group were randomly selected at 24 h after administration and Morris water maze was used to test the ability of learning and memory.Six rats from each group were sacrificed at 48 h after administration and hippocampus and cerebral cortex were removed for determination of the expression of CREB and phospho-CREB (p-CREB) by Western blot.Ressults Compared with group C,the escape latency was significantly prolonged at 2-4 days after administration,the number of animals' swimming across the platform decreased,and the expression of CREB and pCREB in hippocampus and cerebral cortex down-regulated in groups K,K+ N,K+ E,K+ R1 and K+ R2(P ＜0.05 ).Compared with group K,the escape latency was significantly shortened at 2-4 days after administration,the number of animals' swimming across the platform increased,and the expression of CREB and p-CREB in hippocampus and cerebral cortex up-regulated in groups K + R3 and K + R4 ( P ＜ 0.05).Compared with groups K + R1 and K + R2,the escape latency was significantly shortened at 2-4 days after administration,the number of animals' swimming across the platform increased,and the expression of CREB and p-CREB in hippocampus and cerebral cortex up-regulated in groups K+ R3 and K+ P4(P ＜ 0.05).There were no significant differences in the escape latency,the number of animals' swimming across the platform,and the expression of CREB and p-CREB in hippocampus and cerebral cortex between groups K + R1 and K + R2,and between groups K + R3 and K + R4 ( P ＞ 0.05 ).Conclusion RO20-1724 0.75-1.00 mg/kg can improve ketamine-induced cognitive dysfunction by up-regulating CREB and p-CREB expression in hippocampus and cerebral cortex in immature rats. Key words: Phosphodiesterase inhibitors; Ketamine; Cognition disorders; Minors