Comparative study between the effects of yohimbine and sildenafil on erectile dysfunction in stressed male rats

The incidence of erectile dysfunction increases as a result of stressful conditions such as industrialized lifestyles. Both physical and psychological stress may interfere with the reproductive capacity of several species. In this work stress was induced by immersion of rats in cold water [15 minutes/day] for 14 consecutive days. The effects of yohimbine [0.2mg/Kg, i.p.] and sildenafil [20mg/Kg, i.p] on erectile dysfunction of stressed rats were assessed in comparison with control group. Furthermore the levels of testosterone, LH and FSH in blood were evaluated. Results revealed that, immersion of rats in cold water significantly increased mount, intromission, ejaculation latencies and intercopulatory interval indicating a decrease in sexual arousal and motivation, and also decreased ejaculation frequency indicating a decrease in copulatory performance and potency. In addition immersion of rats in cold water for prolonged period could decrease the copulatory activity as evidenced by mating test and decreased testosterone, LH and FSH levels. Results revealed that treatment with yohimbine or sildenafil significantly increased the sexual arousal and potency and corrected the effects induced by stress on the mating behavior of male rats. On the contrary they did not significantly alter testosterone, follicle stimulating hormone [FSH] and luteinizing hormone [LH] levels

Potential antihypertensive and antioxidative effects of Nigella sativa seeds or biomass and Syzygium aromaticum extracts on L-NAME- induced hypertensive rats

Plant tissue culture techniques had captured the attention of researchers in a wide range of scientific areas. The aim of the present investigation is to assess the potential antihypertensive and antioxidative effects of Nigella sativa seeds or biomass and Syzigium aromaticum buds extracts on L-NAME - induced hypertension in rats. In the present study, rats were randomly allocated into 5 groups, all groups except the normal control one were administered N[omega] -nitro-L-arginine methyl ester [L.NAME][50 mg/kg/day p.o] for two weeks. The treatment started after the first week of L-NAME administration; Nigella sativa seeds and biomass extracts were used in a dose of 400 mg/kg and Syzygium aromaticum extract was used in a dose of 100 mg/kg. Blood pressure [systolic, mean and diastolic] and oxidative stress biomarkers: serum LDH activity and nitric oxide level were measured. A significant increase in systolic, mean and diastolic blood pressure was observed by administration of L-NAME, in addition to a significant increase in serum LDH activity and a significant decrease in serum nitric oxide level. Nigella sativa seeds or biomass and Syzigium aromaticum buds extracts normalized the increment in systolic, mean and diastolic blood pressure [p<0.05]. Furthermore, all the test agents reversed the elevated serum LDH level and increased serum nitric oxide level up to three fold. It could be concluded that Nigella sativa seeds and Syzigium aromaticum might have antihypertensive effect which may be mediated through antioxidant action and that the biomass of Nigella sativa may possess an active constituent possessing antihypertensive activity similar to that of the original plant

Protective effect of selenium against the thallium or mercury-induced oxidative stress in rats

In the present study, the possible protective effect of sodium selenite [250. microg/kg] against thallium nitrate [3 mg/kg] and mercuric acetate [1.5 mg/kg] induced oxidative stress was studied in rats. The measured parameters were lipid peroxides [measured as MDA] and lactate dehydrogenase activity [LDH] in serum, liver and kidney. The effects of thallium nitrate and mercuric acetate as well as the combination of each of them with sodium selenite were determined on the aforementioned parameters. Results of the present study showed that thallium nitrate as well as mercuric acetate significantly increased lipid peroxides in serum, liver and kidney. Administration of sodium selenite together with thallium nitrate or mercuric acetate resulted in significant decrease in lipid peroxides in serum, liver and kidney thus exerting significant protection against thallium and mercury-induced oxidative stress Thallium nitrate significantly elevated lactate dehydrogenase activity [LDH] in serum, liver and kidney while mercuric acetate significantly, elevated LDH activity only in serum and liver. Sodium selenite significantly antagonized the effect of thallium and mercury and protected against their toxicity. It could be concluded that sodium selenite can effectively protect against thallium and mercury- induced oxidative stress

Contribution of nitric oxide, monoaminergic and opioidergic systems to the antinociceptive effects of tramadol and clonidine in rats and mice

In this study, thermal and chemical stimuli using hot plate and acetic acid tests were used. Tramadol hydrochloride produced antinociception in both hot plate test in rats and acetic acid analysis in mouse. The antinociceptive activity of tramadol was abolished by naloxone. Administration of yohimbine also reduced antinociception produced by administration of tramadol. These results suggested that tramadol- induced antinociception might be mediated by opioid and non-opioid mechanisms. Clonidine produced dose dependent antinociception using hot plate test. It was concluded that opioid receptors, alpha 2-adrenergic receptors and nitric oxide might play a role in pain transmission