RESUMO
OBJECTIVE: To investigate the negative feedback regulation from rat hippocampus on hypothalamic-pituitary-adrenal (HPA) axis under high temperature and high humidity stress. METHODS: Thirty (30) SD male rats were randomly divided into three groups: control group, high temperature and high humidity group, drug intervention group. The rats in control group were kept in the environment with temperature of 24 ± 1°C and humidity of 50 ± 5%, without any stimulation. The rats in the other groups were exposed to high temperature and high humidity environment for 4 h each day, with temperature of 35±1 °C and humidity of 85±5%. The rats in drug intervention group were intragastrically administered with the glucocorticoid receptor antagonist mifepristone. The administration was continued for 3 weeks. After 3 weeks, the serum levels of corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were detected by ELISA.The protein and mRNA levels of corticosteroid receptors (MR), glucocorticoid receptors (GR) and inducible nitric oxide synthase (iNOS), transient receptor potential vanilloid 1 (TRPV1) and 11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1) in hippocampus were determined by immunohistochemistry and in situ hybridization, respectively. The apoptosis of hippocampal cells was examined with TUNEL apoptosis staining. RESULTS: After stimulation with high temperature and high humidity stress for 3 weeks, the serum levels of CRH, ACTH and CORT in the high temperature and high humidity group were significantly increased compared to that of control group; the levels of these indicators in drug intervention group were decreased compared to that of high temperature and high humidity group (P<0.05). In high temperature and high humidity group, the protein and mRNA levels of MR, GR, iNOS in hippocampus of rats were significantly increased compared with that of control group (p<0.05); and the levels of these indicators in drug intervention group were lower than that of high temperature and high humidity group (p<0.05). In addition, compared with the control group, the TRPV1 protein level in hippocampus of rats in high temperature and high humidity group was not significantly changed (p>0.05), while the TRPV1 mRNA level was significantly increased (p<0.05). Neither the protein nor mRNA levels of 11ß-HSD1 showed significant difference compared to control group (p>0.05). The apoptosis of hippocampus cells in the high temperature and high humidity group was significantly increased compared with that of control group (p<0.05); and it was lower in the drug intervention group than that of in high temperature and high humidity group while the result was not significant (p>0.05). CONCLUSION: High temperature and high humidity stress may up-regulate the local expression of iNOS in hippocampus and decrease the activity of glucocorticoids (GC) receptor, then the effective binding of GR-GC would be decreased and the negative feedback regulation of hippocampus on HPA axis would be inhibited. The glucocorticoid receptor antagonist can improve the negative feedback regulation of hippocampus on HPA axis in rat.
RESUMO
OBJECTIVE: To investigate the protective effect and mechanism of Shenqi Compound on diabetic angiopathy modeled rats. METHODS: Totally 18 SD rats were randomized into 3 groups, i.e., the normal control group, the diabetic mellitus (DM) group, and Shenqi Compound group, 6 in each group. The DM rat model was established by feeding high-fat diet (to induce hyperlipidemia) +intraperitoneal injection of small dose streptozotocin (STZ). Shenqi Compound was given to rats in the Shenqi Compound group at the daily dose of 2 g/kg. Equal volume of normal saline was given to rats in the model group and the normal control group by gastrogavage. All treatment was lasted for 12 weeks. Then 2-D and ultrasonic integrated backscatter technique were used to evaluate structural and functional changes of abdominal aorta in the progression of diabetic macroangiopathy. The fibrosis degree of the aorta vessel and myocardium capillaries were observed by using HE and Masson trichrome staining. The tension of the aortic vascular ring was determined. The transforming growth factor beta (TGF-beta) mRNA expression was detected by real time PCR (RT-PCR). The protein expression of TGF-beta, collagen I, collagen III, connective tissue growth factor (CTGF), and phosphorylation P38 MAPK were detected by Western blot. RESULTS: Compared with the normal control group, abdominal aortic systolic inner diameter, diastolic inner diameter, Peterson elastic modulus, stiffness index, and backscatter integral significantly increased; the rangeability of integral backscatter and the extension coefficient of cross section significantly decreased in the DM group (all P < 0.05). After 12 weeks aforesaid indices were obviously improved in the Shenqi Compound group (P < 0.05). Results of HE and Masson staining showed that the fibrosis degree of the aorta vessel and myocardium capillaries was obviously alleviated in rats of the Shenqi Compound group (P < 0.05). Results of the aortic vascular ring tension showed that acetylcholine induced vasodilatation and maximum diastolic percent were obviously elevated in the Shenqi Compound group (P < 0.05). Compared with the normal control group, the mRNA expression of TGF-beta, and the protein expression of TGF-beta, collagen I, and collagen III, and phosphorylation of P38 MAPK all significantly increased in the DM group (P < 0.05). Compared with the DM group, the mRNA expression of TGF-beta, and the protein expression of TGF-beta, collagen I, and collagen III, and phosphorylation of P38 MAPK all decreased (P < 0.05). CONCLUSIONS: Shenqi Compound could effectively improve the arterial function in diabetic marcoangiopathy and microvascular dysfunction. The mechanism might be due to the down-regulating the expression of TGF-beta, and further suppressing the phosphorylation of P38 MAPK, reducing the synthesis of collagen I and collagen III, therefore, ameliorating arterial and myocardial interstitial fibrosis.
