Effect of Hypericum Perforatum L Extracts on depression induced by chronic unpredictable mild stress in mice

Abstract

Objective To observe the improving effect of Hypericum Perforatum L Extracts (HPLES)on depression induced by chronic unpredictable mild stress in mice. Methods The depression model was established by the method of chronic unpredictable mild stress. Fifty depression model mice were divided into model control group, fluoxetine hydrochloride group (2.6 mg / kg), Hypericum perforatum extract low, medium and high (0.2 g / kg, 0.4 g / kg, 0.8 g / kg) dose groups according to the random number table method. Another 10 normal mice matched with body weight were taken as the normal control group. The mice in normal control group and the model control group were given pure water by gavage every day, and the mice in other groups were given corresponding solution by gavage for 4 weeks. In addition to the normal control group, the mice in other groups continued to undergo chronic unpredictable mild stress during gavage.The sugar water preference test and forced swimming test were performed after the last administration. Blood samples were collected from the posterior orbital venous plexus, and the levels of dopamine (DA) and brain-derived neurotrophic factor (BDNF) were measured by Elisa. The hippocampal tissues of mice were examined by HE staining. Results Compared with the normal control group, the body mass of mice in the model control group decreased significantly at the first, second, third and fourth weeks (t=2.739, 4.162, 4.082, 3.957; all P 0.05). Compared with the normal control group, the sugar water preference index of mice in the model control group was significantly reduced((61.3±4.5)%, (52.6±5.2)%; t=2.721, P<0.05), the swimming immobility time was prolonged((44.3±20.00) s, (101.8±50.8) s; t=2.939, P<0.05), the difference were statistically significant. Compared with the model control group, the sugar water preference index of mice in the low, middle and high dose group of Hypericum perforatum extract increased((61.8±4.7)%, (65.2±4.1)%, (62.6±5.6)%, t=-3.005, 5.073, -2.928, all P<0.05), the swimming immobility time decreased ((47.2±17.9) s, (54.8±50.3) s, (61.3±44.2) s; t=2.803, 1.921, 1.903, all P<0.05). The results of Elisa showed that compared with the normal control group, the levels of serum DA and BDNF of mice in the model control group were significantly lower (t=3.031, 8.507, all P<0.05); compared with the model control group, the levels of serum DA of mice in the low dose and high dose group of Hypericum perforatum were significantly higher (t=5.025, 3.414, P<0.05), and the serum BDNF of mice in the high dose group of Hypericum perforatum was also significantly higher (t=6.098, P<0.05), the difference was statistically significant. HE staining showed that compared with the normal control group, the neurons in CA3 area of hippocampus in the model control group mice were seriously damaged, suggesting the establishment of the mouse model. Compared with the model control group, the atrophy and degeneration of hippocampal CA3 cells in the three dose groups were significantly reduced. The atrophy and deformation of hippocampal CA3 neurons in the low, middle and high dose groups of Hypericum perforatum extract were relieved. Conclusion HPLES have obvious improving and antidepressant effects on the depression model mice induced by chronic unpredictable stress.The above effects may be related to the improvement of serum DA, DBNF level and reduce neuronal damage in CA3 area. Key words: Hypericum perforatum L; Depression; Stress; Forced swimming; Brain-derived neurotrophic factor; Mice