Effect of Wenyang Jieyu Decoction on Hippocampal Neuroplasticity in Depressed Rats Induced by Corticosterone / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the effect of Wenyang Jieyu decoction （WYJY） on the hippocampal structure of depressed rats with kidney-yang deficiency. MethodThe 105 SD rats were randomly divided into normal group， model group， fluoxetine group （4.17 mg·kg-1）， Xiaoyaosan group （1.88 g·kg-1）， and low-， medium- and high-dose （1.25，2.50，5.00 g·kg-1） WYJY groups，15 in each group. The depression model was induced by subcutaneous injection of corticosterone in rats except for those in the normal group and the rats were orally administered once a day for 28 days. The depression-like behaviors of rats were observed by sucrose preference test， novelty-suppressed feeding test， forced swimming test， and open field test. The morphology of hippocampal neurons was observed by hematoxylin-eosin（HE） staining， and the density of hippocampal neurons was detected by Nissl staining. The ultrastructure of hippocampal synapses was observed by transmission electron microscopy （TEM）. The expression of synaptophysin （SYP）， postsynaptic density-95 （PSD95）， and apoptosis-related protein Caspase-3 in hippocampal neurons was observed by immunohistochemistry， and bromodeoxyuridine （BrdU） and doublecortin （DCX） were used to observe the apoptosis and regeneration of hippocampal neurons. ResultWYJY could improve weight loss in depressed rats. As revealed by the behavioral tests， the model group showed depression-like behaviors， which were relieved in the WYJY groups and the positive drug groups. HE staining showed that the nuclei of hippocampal neurons in the model group were constricted， deeply stained， and sparsely arranged， while the neurons in the WYJY groups and the positive drug groups were significantly improved. Nissl staining demonstrated that the cell density of the model group was lower than that of the normal group （P<0.05）. Compared with model group， the groups with drug intervention showed increased cell density （P<0.05） and compact arrangement. According to the results in TEM， compared with normal group， the model group showed shortened synaptic active zone （P<0.05）， widened synaptic cleft （P<0.05）， and thinned tight zone （P<0.05）. Compared with model group， the groups with drug intervention showed shortened synaptic active zone （P<0.05）， narrowed synaptic cleft （P<0.05）， and thickened tight zone （P<0.05）. As displayed by the results of immunocytochemistry and immunofluorescence， compared with the normal group， the model group showed decreased protein expression of SYP， PSD95， BrdU， and DCX in the hippocampus （P<0.05） and increased protein expression of Caspase-3 （P<0.05）. Compared with the model group， the groups with drug intervention showed increased protein expression of SYP， PSD95， BrdU， and DCX in the hippocampus （P<0.05） and decreased protein expression of Caspase-3 （P<0.05）. ConclusionWYJY can promote the regeneration of hippocampal neurons in rats and improve the depression of rats.