Effects of eupatilin on the contractility of corpus cavernosal smooth muscle through nitric oxide-independent pathways.

Eupatilin (5,7-dihydroxy-3,4,6-trimethoxyflavone) is one of the main compounds present in Artemisia species. Eupatilin has both antioxidative and anti-inflammatory properties and a relaxation effect on vascular contraction regardless of endothelial function. We evaluated the relaxant effects of eupatilin on the corpus cavernosum (CC) of rabbits and the underlying mechanisms of its activity in human corpus cavernosum smooth muscle (CCSM) cells. Isolated rabbit CC strips were mounted in an organ bath system. A conventional whole-cell patch clamp technique was used to measure activation of calcium-sensitive K+ -channel currents in human CCSM cells. The relaxation effect of eupatilin was evaluated by cumulative addition (10-5  m ~ 3 × 10-4  m) to CC strips precontracted with 10-5  m phenylephrine. Western blotting analysis was performed to measure myosin phosphatase targeting subunit 1 (MYPT1) and protein kinase C-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17-kDa (CPI-17) expression and to evaluate the effect of eupatilin on the RhoA/Rho-kinase pathway. Eupatilin effectively relaxed the phenylephrine-induced tone in the rabbit CC strips in a concentration-dependent manner with an estimated EC50 value of 1.2 ± 1.6 × 10-4  m (n = 8, p < 0.05). Iberiotoxin and tetraethylammonium significantly reduced the relaxation effect (n = 8, p < 0.001 and p = 0.003, respectively). Removal of the endothelium or the presence of L-NAME or indomethacin did not affect the relaxation effect of eupatilin. In CCSM cells, the extracellular application of eupatilin 10-4  m significantly increased the outward currents, and the eupatilin-stimulated currents were significantly attenuated by treatment with 10-7  m iberiotoxin (n = 13, p < 0.05). Eupatilin reduced the phosphorylation level of MYPT1 at Thr853 of MLCP and CPI-17 at Thr38. Eupatilin-induced relaxation of the CCSM cells via NO-independent pathways. The relaxation effects of eupatilin on CCSM cells were partially due to activation of BKCa channels and inhibition of RhoA/Rho-kinase.

DHEA treatment reduces fat accumulation and protects against insulin resistance in male rats.

The purpose of this study was to determine whether administration of dehydroepiandrosterone (DHEA) protects male rats against the accumulation of body fat the development of insulin resistance with advancing age. We found that supplementation of the diet with 0.3% DHEA between the ages of 5 months and approximately 25 months resulted in a significantly lower final body weight (DHEA, 593 +/- 18 g vs control, 668 +/- 12 g, p < 0.02), despite no decrease in food intake. Lean body mass was unaffected by the DHEA, and the lower body weight was due to a approximately 25% reduction in body fat. The rate of glucose disposal during a euglycemic, hyperinsulinemic clamp was 30% higher in the DHEA group than in the sedentary controls due to a greater insulin responsiveness. The DHEA administration was as effective in reducing body fat content and maintaining insulin responsiveness as exercise in the form of voluntary wheel running. The DHEA had no significant effect on muscle GLUT4 content. A preliminary experiment provided evidence suggesting that muscle insulin signaling, as reflected in binding of phosphatidylinositol 3-kinase to the insulin receptor substrate-1, was enhanced in the DHEA-treated and wheel running groups as compared to controls. These results provide evidence that DHEA, like exercise, protects against excess fat accumulation and development of insulin resistance in rats.