Narrative Review: Pathogenesis of the Inflammatory Response and Intestinal Flora in Depression.

Depression, as a common mental illness that is often accompanied by suicidal and homicidal behaviors, is one of the most important diseases in the medical field that requires urgent attention. The pathogenesis of depression is complex, and the current therapeutic drugs such as tricyclic antidepressants (TCAs), monoamine oxidase inhibitors, and secondary serotonin reuptake inhibitors have certain shortcomings. The inflammatory factor hypothesis, one of the pathogenesis of depression, suggests that inflammatory response is a key factor leading to the occurrence and development of depression, and that overactivation of inflammatory factors such as NLRP3, Toll-like receptor 4, and IDO leads to immune-system dysfunction and depression. The other pathogenic hypothesis, the gut flora hypothesis, has also been the focus of recent research. The gut flora may work together with inflammatory factors to cause depression. The approach to treating depression has been by altering the gut flora through drugs or probiotics. However, effective and clear treatment methods are lacking. In this study, by exploring the involvement of intestinal flora and inflammatory factors in the pathogenesis of depression, we found that improving the intestinal flora can affect inflammatory factors and, therefore, provide research ideas for the development of novel drugs to treat depression.

[Electroacupuncture at "Zusanli"(ST36) ameliorates tau hyperphosphorylation in pancreas and hippocampus of diabetic rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) at "Zusanli"(ST36) on the phosphorylated tau levels in pancreas and hippocampus of type 2 diabetes mellitus (T2DM) rats，so as to explore the underlying mechanism of EA in diabetic demention rats. METHODS: Forty-eight male Sprague-Dawley rats were randomly divided into control, model and EA groups, with 16 rats in each group. The T2DM model was established by 6 weeks of high-fat, high-sugar diet as well as intrape-ritoneal injection of streptozocin (STZ) solution (35 mg/kg). After that, EA (2 Hz, 0.1 mA) was applied to unilateral "Zusanli"(ST36) for 30 min, once a day, 6 times a week for 4 weeks. The survival rate was recorded every week, and the fasting blood glucose (FBG) was detected on the 1st, 6th and 11th week. The level of serum insulin (INS) was measured by using ELISA. The morphological structure of pancreas islet was observed by H.E. staining. The expressions of phosphorylated tau at the sites of Ser 396 (pS396) and Thr 231 (pT231), total tau (Tau5), phosphorylated glycogen synthase kinase-3ß (pGSK-3ß) and total glycogen synthase kinase-3ß (GSK-3ß) in pancreas and hippocampus were detected by Western blot. The expression and distribution of pS396 and pT231 in pancreas and hippocampus were assayed with immunohistochemistry. RESULTS: Compared with the control group, the survival rate presented a significant decline, the contents of FBG and INS were obviously higher(P<0.01), and the structure of the pancreas islet appeared shrunken, obscure and disordered in the model group. Furthermore, the levels of pS396, pT231 in pancreas and hippocampus were obviously higher in the model group(P<0.01)，while the level of pGSK-3ß in pancreas and hippocampus was significantly lower in the model group(P<0.01). In comparison with the model group, the survival rate of EA group was higher. Following 4 weeks' interventions, the enhanced levels of tau phosphorylation and GSK-3ß activity in pancreas and hippocampus were partly reversed in the EA group compared to the model group(P<0.05，P<0.01). CONCLUSION: EA at ST36 can reduce the level of tau phosphorylation via regulating the activity of GSK-3ß in the pancreas and hippocampus of T2DM rats, which may be related with the effect of EA on the brain function in T2DM rats.

Puerarin Ameliorates D-Galactose Induced Enhanced Hippocampal Neurogenesis and Tau Hyperphosphorylation in Rat Brain.

Enhanced neurogenesis has been reported in the hippocampus of patients with Alzheimer's disease (AD), the most common neurodegenerative disorder characterized with amyloid-ß (Aß) aggregation, tau hyperphosphorylation, and progressive neuronal loss. Previously we reported that tau phosphorylation played an essential role in adult hippocampal neurogenesis, and activation of glycogen synthase kinase (GSK-3), a crucial tau kinase, could induce increased hippocampal neurogenesis. In the present study, we found that treatment of D-galactose rats with Puerarin could significantly improve behavioral performance and ameliorate the enhanced neurogenesis and microtubule-associated protein tau hyperphosphorylation in the hippocampus of D-galactose rat brains. FGF-2/GSK-3 signaling pathway might be involved in the effects of Puerarin on hippocampal neurogenesis and tau hyperphosphorylation. Our finding provides primary in vivo evidence that Puerarin can attenuate AD-like enhanced hippocampal neurogenesis and tau hyperphosphorylation. Our finding also suggests Puerarin can be served as a treatment for age-related neurodegenerative disorders, such as AD.