Monoamine neurotransmitter changes in hippocampus at reserpine induced chronic animal model of depression

Objective To observe the suitable dosage of reserpine for the establishment of rat model of depression and analyze the changes of monoamine neurotransmitter in hippocampus. Methods 60 rats were randomly divided into five groups: the normal group, the 0.3 mg/kg group, 0.4 mg/kg group, 0.5 mg/kg group and 0.6 mg/kg group, and 12 rats in each group.The model groups were intraperitoneally administrated by different dosage of reserpine (according to the dosage of the grouping) for 14 days and rats in the normal group were injected the same volume of solvent. The body weight was recorded at different days and activity was tested by open-field test at 0, 7th and 14th day. Monoamine neurotransmitter changes in hippocampus were tested by enzyme-linked immunosorbent assay. Results Reserpine could cause body weight loss (0.5, 0.6 mg/kg) and depressive behavior (0.4, 0.5, 0.6 mg/kg). The group of 0.4 mg/kg showed no difference in weight and open-field test. Compared with the weight body((278.75±4.65)g) and open-field test (60.3±19.9) at the model group, the group of 0.5 mg/kg at 14th showed significant differences in weight ((256.17±4.89)g) and behavior(43.4±8.4)(P<0.01). Dosage of 0.5 mg/kg had effect to 5-HT in hippocampus at 7th day ((2.83±1.09)ng/ml, P<0.01) but not 14th day. Compare with the normal group at 14th day, the group of 0.5 mg/kg showed no difference at 5-HT, DA and NA, and there was significant negative correlation between 5-HT and NA(r=-0.449, P<0.01). Conclusion Reserpine of 5 mg/kg can result in the depressive behavior of rats. The effect of reserpine to monoamine neurotransmitter in hippocampus has relationship with time. Key words: Reserpine; Depression; Model; Monoamine neurotransmitter