Voluntary wheel running exercise regulates microglia polarization in hippocampus through STAT3 signal pathway to inhibit depression-like behavior induced by chronic stress in rats / 生理学报

This paper was aimed to investigate the effect of voluntary wheel running exercise on depression-like behavior induced by chronic water immersion restraint stress (CWIRS) and the underlying mechanism. Sprague-Dawley (SD) rats received CWIRS to induce depression-like behavior and 4-week voluntary wheel running exercise. Meanwhile, the rats were treated with lipopolysaccharide (LPS) or STAT3 over-expression vector (pcDNA-STAT3) by intracerebroventricular injection. Behavioral tests were used to detect depression-like behavior. ELISA assay was used to detect levels of various inflammatory factors in the rat hippocampus. Western blot was used to detect protein expression levels of ionized calcium binding adaptor molecule 1 (Iba1), inducible nitric oxide synthase (iNOS), arginase 1 (Arg1), phosphorylated STAT3 (p-STAT3) and total STAT3 (t-STAT3). The results showed that, compared with stress group, stress + exercise group exhibited improved depression-like behavior, decreased interleukin-1β (IL-1β) and IL-6 levels, increased IL-4 and IL-10 levels, down-regulated Iba-1 and iNOS protein expression levels, up-regulated Arg1 protein expression level, and decreased p-STAT3/t-STAT3 ratio in hippocampal tissue. LPS reversed the improving effect of voluntary wheel running exercise on depression-like behavior in rats, and the over-expression of STAT3 reversed the promoting effects of voluntary wheel running on M2 polarization of microglial cells in rat hippocampus and depression-like behavior. These results suggest that voluntary wheel running ameliorates the depression-like behavior induced by CWIRS in rats, and the mechanism may be related to regulating hippocampal microglia polarization via STAT3 signaling pathway.

Capsaicin inhibits experimental autoimmune neuritis in rats through inhibition of autophagy activity / 中国药理学通报

Aim To observe the effect of capsaicin on the experimental autoimmune neuritis (EAN) in rats and explore the mechanism.Methods To induce EAN,male Lewis rats were immunized with peripheralnerve myelin sheath antigen (P257481) peptide and complete Freund's adjuvant (CFA) mixed liquor.Rapamycin (RAPA,2.5 mg · kg-1) was administered by intraperitoneal injection 0.5 h after immunization and capsaicin (1 mg · kg-1 · d-1) was administered by intragastric administration 1.0 h after immunization for 15 days.The incidence and clinical characteristics of EAN were observed.The clinical scores of neurological signs were completed and body weight was measured.Pathological morphology of sciatic nerve was observed by HE staining and Lauck fast blue staining.Ultrastructure of sciatic nerve was observed by transmission electron microscope.Levels of serum tumor necrosis factor alpha (TNF-α),interferon gamma (IFN-γ),interleukin 1β (IL-1β) and intedeukin-6 (IL-6) were tested by enzyme linked immunosorbent assay (ELISA).Expressions of autophagy related protein were measured by Western blot.Results Compared with EAN group,the clinical scores of neurological signs significantly decreased from day 7 to day 16 of post-immunization (P ＜ 0.05),body weight significantly increased from day 3 to day 16 of post-immunization (P ＜ 0.05),demyelination obviously decreased,inflammatory cell infiltration number obviously decreased (P ＜ 0.05),the levels of TNF-α,IFN-γ,IL-1β and IL-6 significantly decreased (P ＜ 0.05),the number of autophagosome in axon of sciatic nerve significantly decreased (P ＜ 0.05),and expressions of Beclin-1 and LC3-Ⅱ and the ratio of LC3-Ⅱ and LC3-Ⅰ were significantly down-regulated,and the expression of p62 was significantly up-regulated (P ＜ 0.05) in EAN + capsaicin group.Rapamycin partially reversed the action of capsaicin.Conclusions Capsaicin inhibits EAN in rats,and the mechanism may be related with the inhibition of autophagy activity.

Dihydromyricetin inhibits PC12 cell injury induced by 1-methyl-4-phenylpyridinium by up-regulating autophagy activity / 中国药理学与毒理学杂志

OBJECTIVE To observe the effect of dihydromyricetin (DMY) on cell injury induced by 1-methyl-4-phenylpyridinium (MPP+) in PC12 cells and explore the possible mechanism. METHODS After being pretreated with DMY 5, 10, 20, 40 and 80 μmol · L-1 for 0.5 h, PC12 cells were incubated with DMEM culture medium including autophagy inhibitor 3-methyladenine (3-MA) 10 mmol · L-1 and MPP+500μmol·L-1 for 48 h. MTT Assay was used to test the viability of PC12 cells. The level of lactate dehy-dregenase (LDH) was measured colorimetrically. The ultrastructure of PC12 cells was observed under transmission electron microscope. Expressions of autophagy related protein, Beclin-1, microtubule-associated protein light chain 3 (LC3) and p62 were measured by Western blotting. RESULTS Compared with cell control group, the cell survival rate was significantly decreased, the level of LDH was signifi-cantly increased, the number of autophagosomes was obviously decreased, the percentage of autophagic vacuoles in the total cytoplasm area was significantly decreased (P<0.05), expression of Beclin-1 and LC3-Ⅱ and the ratio of LC3-Ⅱ to LC3-Ⅰ were significantly down-regulated (P<0.05) and the expres-sion of p62 was significantly up-regulated in MPP+group (P<0.05). Compared with MPP+group, the cell survival rate was significantly increased, while the level of LDH was significantly decreased in MPP++DMY 10-80 μmol · L-1 group (P<0.05). Compared with MPP+ group, the number of autophagosomes obviously increased, the percentage of autophagic vacuoles in the total cytoplasm area was significantly increased, the expression of Beclin-1 and LC3-Ⅱ and the ratio of LC3-Ⅱ to LC3-Ⅰwere significantly up-regulated and the expression of p62 was significantly down-regulated in MPP++DMY 20 μmol · L-1 group (P<0.05). Compared with MPP++DMY 20μmol · L-1 group, the cell survival rate was significantly decreased, but the level of LDH was significantly increased in MPP ++DMY+3-MA group (P<0.05). CONCLUSION DMY may inhibit the cell injury induced by MPP+in PC12 cells, and the mechanism may be related to the up-regulation of autophagy activity induced by DMY.

Preventive effects of rosiglitazone against diabetic optical neuropathy / 中华实验眼科杂志

Background Optic neuropathy is one of the diabetic eye complications.Rosiglitazone,a peroxisome proliferator activated receptor γ(PPARγ) agonist,plays a very important role in arresting the pathogenesis and development of diabetes.However,the role of PPARγ in diabetic optic neuropathy is unclear.Objective This study was to investigate the protective effect of rosiglitazone against diabetic optic neuropathy and its mechanism.Methods Male Sprague-Dawley rats were randomly divided into the control group,diabetic group and rosiglitazone group,with 10 rats for each group.Diabetic models were induced by injecting 50 mg/kg of streptozotocin via the caudal vein,and rosiglitazone(5 ng/[kg· d])was used in the rats of the rosiglitazone group by intragastric administration every day for four weeks.At the end of the experiment,the fasting blood sugar(FBS) was tested in all the animals.The level of vascular endothelial growth factor(VEGF) in the blood plasma was detected by ELISA.Optical neural tissues were obtained from the rats of each group,and Lauck fast Blue myelin stain was used to examine the morphology of the optical myelin.The expression of neural cell adhesion molecule (NCAM) mRNA and protein in the optic nerve was detected by real time PCR and Western blot,respectively.Results The levels of FBS,blood plasma VEGF,NCAM mRNA and protein in the optic nerve were significantly different among the control group,diabetic model group and the rosiglitazone group after the administration of 5 nmg/(kg · d) rosiglitazone for 4 weeks (F =6.12,P＜0.01 ; F =5.14,P＜0.05 ; F =4.75,P＜0.05 ; F =4.87,P＜0.05).Compared with the control group,the level of FBS significantly increased in the diabetic model group(t =2.26,P＜O.05),and that in the rosiglitazone group significantly declined in comparison with the diabetic model group(t=2.08,P＜0.05).The optic nerve exhibited a normal morphology in the control group as revealed by the Lauck fast Blue myelin staining;however,severe demyelination of the optic nerve and proliferation of glial cells were found in the diabetic model group,and mild demyelination of the optic nerve and proliferation of glial cells were seen in the rosiglitazone group.Blood plasma VEGF was(28.76±4.21)ng/L in the control group and(134.28±11.36)ng/L in the diabetic model group,showing a significant difference between them (t=2.36,P ＜ 0.05).Compared with the model group,the blood plasma VEGF was significantly lower in the rosiglitazone group ([42.67 ± 5.83] ng/L) than that in the diabetic model group (t =2.17,P＜ 0.05).Expression of NCAM mRNA and protein in the optic nerve significantly decreased in the diabetic model group compared with the control group(t =2.21,t =2.58,both at P＜0.05);while those in the rosiglitazone group were significantly elevated in comparison with the diabetic model group(t =2.19,t =2.67,both at P＜O.05).Conclusions Rosiglitazone can protect optic nerve from damage in diabetic rats mainly by downregulating blood plasma VEGF level and upregulating NCAM expression.

Effects of rosiglitazone on aortic function in rats with insulin resistant-hypertension / 生理学报

Rosiglitazone (ROSI), thiazolidione peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activator, reduces insulin resistance in patients with type 2 diabetes (T2DM). It also improves vascular reactivity in T2DM patients and some animal models by unclear mechanisms. In order to investigate the effect of ROSI on aortic systolic and diastolic function of insulin resistant-hypertensive rats (IRHR) and the underlying mechanism, male Sprague-Dawley (SD) rats were fed with high fructose (HF) for 8 weeks to induce IRHR model. To verify IRHR model, systolic blood pressure (SBP), fasting blood sugar (FBS), fasting serum insulin (FSI) were measured respectively in each group, and insulin sensitive index (ISI) was also calculated. Subsequently, the vascular function test was performed. The thoracic aortic ring of SD rats was mounted on a bath system. The effect of rosiglitazone on the contraction elicited by L-phenylephrine (PE) and potassium chloride (KCl) and the relaxation induced by acetylcholine (ACh) and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) was used and serum nitric oxide (NO) was measured. The results obtained were as follows: (1) Rosiglitazone reduced the level of SBP, serum insulin and improved insulin resistance in IRHRs. (2) The contractive responses of thoracic aortic rings to PE and KCl were enhanced and the relaxation response to ACh was depressed significantly in the HF group, and the effect was reversed by ROSI. (3) After pretreatment with L-NAME, the relaxation response to ACh was further impaired in the HF group, this effect was partly reversed by ROSI. (4) Sodium nitroprusside (SNP)-induced vasodilator responses did not differ significantly among the groups. (5) Aortic systolic and diastolic function of the control group was not affected markedly by ROSI. (6) Compared with the control group, serum nitric oxide was significantly reduced in the HF group, but after rosiglitazone treatment it was remarkably increased. These findings suggest that ROSI can improve aortic diastolic function of insulin resistant-hypertensive rats, the mechanism of this effect might be associated with an increase in nitric oxide mediated partly by NOS pathway, a decrease in the level of blood pressure, serum insulin and the improvement of insulin resistance.

17β-estradiol protects against injury of aortic relaxation and contraction in ovariectomized rats with insulin resistance induced by fructose / 生理学报

The purpose of the present study was to investigate the effect of 17beta-estradiol (17beta-E(2)) on the structure and relaxation and contraction activity of thoracic aortas in ovariectomized rats with insulin resistance induced by fructose. Ovariectomized mature female Sprague-Dawley rats were fed with high fructose diet for 8 weeks to induce insulin resistance. Physiological dose of 17beta-E(2) (30 mug/kg) was injected subcutaneously every day for 8 weeks. Systolic blood pressure (SBP) was measured by use of tail-cuff. Serum nitric oxide (NO), estradiol (E(2)), fasting blood sugar (FBS) and fasting serum insulin (FSI) were measured respectively in each group. The insulin sensitive index (ISI) was calculated. The thoracic aortas were fixed in formalin, sliced and HE dyed. The structure of thoracic aortas, lumen breadth, media thickness, media thickness/lumen breadth ratio and media cross-section area were measured. The contraction response of thoracic aorta rings induced by L-phenylephrine (PE) and the relaxation response of thoracic aorta rings induced by ACh and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N-nitro-L-arginine methyl ester (L-NAME) was used. The results obtained are as follows: (1) 17beta-E(2) protected against the effect of high fructose diet, which caused an increase in SBP, hyperinsulinemia and a decrease in ISI in ovariectomized rats. (2) The structure of thoracic aortas had no significant difference among the groups. (3) Compared with the ovariectomized group (OVX) or fructose fed group (F), serum nitric oxide was significantly reduced, the contraction response of thoracic aorta rings to PE was enhanced and the relaxation response to ACh was depressed significantly in ovariectomized+fructose fed group (OVX+F). The effect of high fructose was reversed by 17beta-E(2). After pretreatment with L-NAME, the effect of 17beta-E(2), which enhanced the relaxation response of thoracic aorta rings to ACh in ovariectomized+fructose+17beta-E(2) group (OVX+F+E(2)), was partly blocked. (4) The relaxation response of thoracic aorta rings to SNP had no significant difference among the groups. (5) The contraction response of thoracic aorta rings without endothelium to PE had no significant difference among the groups. These findings suggest that 17beta-E(2) may provide protection against the effect of high fructose diet, which causes hypertension, dysfunction of endothelial cells and insulin resistance. The mechanism of this effect of 17beta-E(2) could be partly associated with the increase of NO by NOS pathway, or associated with the decrease in the level of systolic blood pressure and serum insulin, and the improvement of insulin resistance.