Post-traumatic stress disorder (PTSD) is a devastating mental illness with high morbidity and major social and economic burden. Currently, there is no promising therapy available for the treatment of PTSD. Some clinical studies showed that ketamine could effectively alleviate PTSD symptoms. However, it is still unclear which brain region ketamine targets and how it attenuates the PTSD-like effects. In this study, we examined the effect of ketamine on fear generalization (a core symptom of PTSD) by using a mice model of fear generalization induced by fear conditioning procedure. Before retrieval, ketamine was locally infused into the nucleus accumbens (a brain region closely associated with PTSD). Fear generalization mice were subjected to behavioral testing and biochemical assessments, following ketamine infusion. The results showed that the foot shock strength-dependently induced fear generalization in mice with increased c-fos activity, and a lower level of GluR1(S845), GluR1(S831) protein, and a higher level of P-GluN2B protein in the nucleus accumbens (NAc). Local infusion of ketamine into NAc decreased the fear generalization together with an increased level of GluR1(S845), GluR1(S831) protein, and decreased level of P-GluN2B protein. Altogether, these results conclude that ketamine might affect the glutamatergic signaling in the NAc to attenuate the fear generalization in mice.
Keywords: Fear generalization; GluN2B; GluR1; Ketamine; Nucleus accumbens; PTSD.
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