Abstract:Objective To investigate the effect of Agomelatine on behavioral manifestations of rats with posttraumatic stress disorder (PTSD). Methods Thirty-two male SD rats were randomly divided into a control group (no drug, no stress, n = 8), an SPS ﹠ S group (no drug, single prolonged stress ﹠ foot shock stress, n = 8), a drug group (drug and stress, n = 8) and a single drug group (drug, no stress, n = 8). The rats of the drug group and the single drug group were administrated with Agomelatine in a dosage of 2.6 mg/(kg·d) by gavage within 12 h after stress for 2 w, while the control group and the SPS ﹠ S group were administrated with the same dose of saline for 2 w. After that the rats in the SPS ﹠ S group and the drug group were stimulated with SPS ﹠ S, the conditioned fear response was observed on the 14th d in the electric shock box. On the 15th d the open-field test was conducted in each group to observe the anxiety behaviors, while from the 16th d to the 21st d, the Morris water maze test was done to observe the navigation capability and the space exploration ability of the rats. Results After SPS ﹠ S stress, the retention time of the rats in the electric shock box was significantly prolonged while the crossing score and rearing score of the rats decreased significantly in the open-field test, and the Morris water maze test also indicated the escape latency period of the rats increased while the number of crossing platform decreased. Furthermore, compared with the SPS﹠S group, early intervention of Agomelatine after the stress obviously ameliorated sluggish behavior, anxiety state and performance of the rats in the Morris water maze (P < 0.05). Conclusions After stress, the alertness and anxiety of the rats are sharply increased while the learning and memory functions obviously decrease. However, early intervention of Agomelatine after stress could significantly reduce the fear and anxiety-like behaviors of the rats with PTSD and can also prevent the loss of learning and memory functions in rats.