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Curcumin exerts a hypoglycemic action and induces heme-oxygenase-1 (HO-1).We evaluated the effect of curcumin on isolated islets of Langerhans and studied whether its action on insulin secretion is mediated by inducible HO-1. Islets were isolated from rats and divided into control islets, islets incubated in different curcumin concentrations, islets incubated in hemin, islets incubated in curcumin and HO inhibitor, stannous mesoporphyrin (SnMP), islets incubated in hemin and SnMP, islets incubated in SnMP only, and islets incubated in 16.7 mmol/L glucose. Heme-oxygenase activity, HO-1 expression, and insulin estimation was assessed. Insulin secretion, HO-1 gene expression and HO activity were significantly increased in islets incubated in curcumin, hemin, and glucose compared with controls. This increase in insulin secretion was significantly decreased by incubation of islets in SnMP. The action of curcumin on insulin secretion from the isolated islets may be, in part, mediated through increased HO-1 gene expression. [ABSTRACT FROM AUTHOR]

Aim: To assess heme oxygenase-1 (HO-1) activity in the cavernous tissue of sildenafil citrate-treated rats. Methods: One hundred and ninety-two Sprague-Dawley male rats, divided into four equal groups, were investigated. Group 1, the control group, received regular animal chow; group 2 received sildenafil citrate by intragastric tube; group 3 received sildenafil and HO inhibitor (zinc protoporphyrin, ZnPP); and group 4 received sildenafil and nitric oxide synthase (NOS) inhibitor L-nitroarginine methyl ester (L-NAME). Twelve rats from each group were killed after 0.5 h, 1 h, 2 h and 3 h of drug administration. Then HO-1 activity, cGMP levels and NOS enzymatic activity in the cavernous tissues were estimated. Results: In cavernous tissue, HO-1 activity, NOS enzymatic activity and cGMP concentration increased significantly in sildenafil-treated rats compared to other groups throughout the experiment. Rats receiving either HO or NOS inhibitors showed a significant decrease in these parameters. HO-1 cavernous tissue activity and NOS enzymatic activity demonstrated a positive significant correlation with cGMP levels ( r= 0.646, r= 0.612 respectively; P < 0.001). Conclusion: The actions of PDE5 inhibitor sildenafil citrate in the cavernous tissue are partly mediated through the interdependent relationship between both HO-1 and NOS activities. [ABSTRACT FROM AUTHOR]

Introduction. Curcumin is an inducer of heme oxygenase enzyme-1 (HO-1) that is involved in erectile signaling via elevating cyclic guanosine monophosphate (cGMP)levels. Aim. To assess the effect of oral administration of a water-soluble long-acting curcumin derivative on erectile signaling. Methods. Two hundred and thirty six male white albino rats were divided into four groups; group 1 (N = 20) includes control. Group 2 (N = 72) was equally divided into four subgroups; subgroup 1 received pure curcumin (10 mg/kg), subgroup 2 received the long-acting curcumin derivative (2 mg/kg), subgroup 3 received the long-acting curcumin derivative (10 mg/kg), and subgroup 4 received sildenafil (4 mg/kg). Subgroups were sacrificed after the first, second, and third hour. Group 3 (N = 72) was equally divided into the same four subgroups already mentioned and were sacrificed after 24 hours, 48 hours, and 1 week. Group 4 (N = 72) was subjected to intracavernosal pressure (ICP) measurements 1 hour following oral administration of the same previous doses in the same rat subgroups. Main Outcome Measure. Cavernous tissue HO enzyme activity, cGMP, and ICP. Results. In group 2, there was a significant progressive maintained elevation of HO activity and cGMP tissue levels starting from the first hour in subgroups 3 and 4, whereas, the rise in HO activity and cGMP started from second hour regarding the other rat subgroups. Sildenafil effect decreased after 3 hours. In group 3, there was a significant maintained elevation of HO activity and cGMP tissue levels extended to 1 week as compared to controls for all rat subgroups that received both forms of curcumin. In group 4, long-acting curcumin derivative exhibited more significant potentiation of intracavernosal pressure as compared to control and to the pure curcumin. Conclusion. Water-soluble long-acting curcumin derivative could mediate erectile function via upregulating cavernous tissue cGMP. Abdel Aziz MT, El Asmer MF, Rezq A, Kumosani TA, Mostafa S, Mostafa T, Atta H, Abdel Aziz Wassef M, Fouad HH, Rashed L, Sabry D, Hassouna AA, Senbel A, and Abdel Aziz A. Novel water-soluble curcumin derivative mediating erectile signaling. J Sex Med 2010;7:2714–2722. [ABSTRACT FROM AUTHOR]

Introduction. Heme oxygenase (HO) enzyme catalyzes oxidative degradation of heme to biliverdin and carbon monoxide (CO). CO shares many properties with nitric oxide (NO) including the activation of soluble guanyl cyclase. Aim. To assess cavernous tissue HO activity and cyclic guanosine monophosphate (cGMP) levels in response to oral phosphodiesterse type 5 (PDE5) inhibitors. Methods. Seven hundred twenty male Sprague-Dawley rats, divided into six groups, were investigated. Group 1, controls; group 2 received sildenafil citrate orally; group 3 received vardenafil hydrochloride; and group 4 received tadalafil. Group 5 was subdivided into three equal subgroups, received the same dose of each drug added to the HO inhibitor, Zn protoporphyrin. Group 6 was subdivided into three equal subgroups, received the same dose of each drug added to the NO inhibitor, L-nitroarginine methylester. Eight rats from each group/subgroup were sacrificed at 0.5, 1, 2, 3, 4, 6, 18, 24, and 36 hours, respectively. Main Outcome Measures. HO enzyme activity assay and cGMP tissue levels in dissected rat cavernous tissues. Results. Both cavernous tissue HO enzyme activity and cGMP levels were increased significantly in sildenafil-, vardenafil-, and tadalafil-treated rats compared with the controls, with significant decreases after either HO or NO inhibition. Cavernous tissue HO enzyme activity and cGMP showed a positive significant correlation ( r = 0.854, P < 0.001). Conclusion. The effects of PDE5 inhibitors in cavernous tissue are partly mediated through HO enzyme activity. Abdel Aziz MT, Mostafa T, Atta H, Rashed L, Marzouk SA, Obaia EM, Sabry D, Hassouna AA, El-Shehaby AM, and Abdel Aziz AT. The role of PDE5 inhibitors in heme oxygenase–cGMP relationship in rat cavernous tissues. J Sex Med 2008;5:1636–1645. [ABSTRACT FROM AUTHOR]