Mutation of the histidin residue of the DRH motif in vasopressin V2 receptor expression and function

Vasopressin type 2 receptor [V2R], a G protein coupled receptor [GPCR], plays an important role in the regulation of renal antidiuretic function. The highly conserved DRH motif is essential for G protein signaling of V2R; however its role especially regarding the histidin residue is not fully understood. Site directed mutagenesis was performed with replacements of the histidin to isoleucine by using nested polymerase chain reaction. ELISA was performed for receptor expression assay and the adenylyl cyclase activity assay was performed for functional characterization of DRI mutation on V2R signaling. The adenylyl cyclase activity assay in COS-7 cells showed no difference in the amount of cAMP production between the wild type and the mutant V2 receptors. The V2 receptor expression was not changed in the presence of this mutation using ELISA assay. These results suggest that the role of histidin residue is not critical in the V2 receptor function, however further mutagenesis studies are required to define the role of this motif in V2R function

effect of AT[1] receptor blockade on BAX and BCL-2 expression in bleomycin-induced pulmonary fibrosis

Recent studies have indicated the role of apoptosis and angiotensin in the pathogenesis of bleomycin induced-pulmonary fibrosis. Losartan, an angiotensin type 1 receptor [AT1R] antagonist, has ameliorated apoptosis and fibrosis from bleomycin. In this study, alterations in the expression of apoptosis-regulatory genes [bcl-2 and bax] were investigated in different cells of lung tissue of mice treated with bleomycin in the presence of losartan. Losartan [10 mg/kg, i.p.] was given to mice two days before administration of bleomycin [3 U/kg] and throughout the test period. After two weeks, lung tissues of mice were evaluated for fibrosis by biochemical measurement of collagen deposition and semiquantitative analysis of pathological changes of the lung. The expression of bcl-2 and bax was assessed by immunohistochemical assay using biotin-streptavidin staining method on paraffin-embedded lung tissues. Pre-treatment with losartan significantly [P < 0.05] reduced the increase in lung collagen content and also inhibited the histological changes induced by bleomycin. Immunohistochemical studies showed that losartan significantly [P < 0.05] reduced the bax/bcl-2 expression ratio in the alveolar epithelial cells, lymphocytes, macrophages and interstitial myofibroblasts. Losartan also inhibited the bcl-2 upregulation which was educed by bleomycin in neutrophils. By reduction of bax/bcl-2 ratio as a determinant of susceptibility of a cell to apoptosis, losartan exerted protective effects on the alveolar epithelial cells that may be important in the amelioration of pulmonary fibrosis. These results may help to better understanding of the role of angiotensin II and apoptosis in pulmonary fibrosis

[Water extract of juglans regia L. and diabetes mellitus in Iranian traditional medicine]

There are many reports about the glucose lowering effects of medicinal plants in animal models. There are a some reports in Iranian traditional medicine about glucose lowering effect of septum water extract of Juglans Regia L. In the present study, effect of aqueous extract of the septum of Juglans Regia L. on plasma glucose is assessed. After preparing the water extract of Juglans Regia L. and concentrating of it the lyophilized extract, was tested in diabetic [ip injection of streptozocin] and normal rats. Comparison between groups was made by analysis of variance [ANOVA] and the differences between the means assessed using student's t test. In an oral glucose tolerance test [OGGT], a single oral administration of the water extract at doses of 50, 250 and 750 mg/kg body weight didn't lowered the plasma glucose level in the normal rats. Although that insulin administration [5IU/kg] caused a reduction of serum glucose[P<0.001], none of the extract doses [1000, 750, 500, 250mg/Kg] could cause a significant reduction in such level [P>0.005]. These results demonstrated that the water extract of the septum of Juglans regia's fruit didn't have a significant hypoglycemic effect in rats

[ effects of silymarin in bleomycin-induced pulmonary fibrosis in mice]

Silymarin, the active principle of Silybum marianum, has antifibrotic effects in hepatic fibrosis by several mechanisms. Since the pathogenesis of fibroproliferative diseases is similar, the effect of silymarin in bleomycin-induced pulmonary fibrosis was evaluated in this study. Silymarin [50 mg/kg, i.p.] was administered two days before the bleomycin instillation [3 U/kg] and throughout the test interval in mice. After two weeks, lung tissues of mice were evaluated for fibrosis by biochemical measurement of collagen deposition and histological analysis of pathological lung changes. Data were evaluated by one-way ANOVA and Dunnett analysis. P<0.05 was considered as significant. Pretreatment with Silymarin significantly [P<0.05] prevented the increase in lung collagen content and also partially inhibited the histologic changes induced by bleomycin. The wet lung weight in silymarin group was similar to that of control group and significantly lower than bleomycin group [P<0.001]. The results of this study indicate that silymarin may prevent the collagen deposition and inflammation and may be protective in fibrogenic effects of bleomycin on lung