Effect Neonatal Ketamine Treatment on Exploratory and Anxiety-like Behaviours in Adulthood

Objective: In this study, we evaluated the effect of neonatal ketamine exposure on anxiety-like and exploratory behaviours in adult the Balb/c and C57BL/6 strains of mice which anxiety responses are different.

Methods: Ketamine was administered at two different doses single dose (10, 20 mg/kg, 0.1 ml/10 g body weight, intraperitoneally) and repeated doses (10, 20 mg/kg every 240 minutes; thrice times) on the 7th postnatal day to male Balb/c and C57BL/6 mice. In adulthood, open-field (OF) and elevated plus maze (EPM) apparatuses were used to evaluate exploratory and anxiety-like behaviour.

Results: In the C57BL/6 mice, the 20 mg/kg single dose decreased open-arm time and total-arm entries in EPM and increased time of central latency and decreased distance travelled in OF. Both the 10 and 20 mg/kg repetitive doses increased time of central latency and decreased time spent in the centre, frequency of rearing and centre crossing in OF and decreased open-arm time, total-arm entries, number of open-arm entries in EPM. The 20 mg/kg repetitive dose decreased number of head dipping behaviours in EPM. In the Balb/c mice, both the single and repetitive 10−20 mg/kg doses had no significant effect on anxiety-like and exploratory behaviours.

Conclusion: There were no significant differences in anxiety-like and exploratory behaviour in different strains by the single 10 mg/kg dose. However, in the C57BL/6 mice, both the single and repetitive 20 mg/kg doses and the 10 mg/kg repetitive dose increased anxiety-like behaviour and decreased exploratory behaviour in EPM and OF. In conclusion, hereditary factors may be effective on the effect of neonatal ketamine treatment on anxiety-like and exploratory behaviour.