In the present study, we investigated the pharmacological action of hydrogen sulfide (H2S, using sodium hydrosulfide, NaHS, and/or sodium sulfide, Na2S as donors) on sympathetic neurotransmission from isolated, superfused porcine iris-ciliary bodies. We also examined the effect of H2S on norepinephrine (NE), dopamine and epinephrine concentrations in isolated porcine anterior uvea. Release of [3H]NE was triggered by electrical field stimulation and basal catecholamine concentrations was measured by high performance liquid chromatography (HPLC). Both NaHS and Na2S caused a concentration-dependent inhibition of electrically evoked [3H]NE release from porcine iris-ciliary body without affecting basal [3H]NE efflux. The inhibitory action of H2S donors on NE release was attenuated by aminooxyacetic acid (AOA) and propargyglycine (PAG), inhibitors of cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE), respectively. With the exception of dopamine, NaHS caused a concentration-dependent reduction in endogenous NE and epinephrine concentrations in isolated iris-ciliary bodies. We conclude that H2S can inhibit sympathetic neurotransmission from isolated porcine anterior uvea, an effect that is dependent, at least in part, on intramural biosynthesis of this gas. Furthermore, the observed action of H2S donors on sympathetic transmission may be due to a direct action of this gas on neurotransmitter pools.

Super CitriMax (HCA-SX) is a novel calcium/potassium salt of (-)-hydroxycitric acid extracted from the dried fruit rind of the plant Garcinia cambogia, and commonly consumed as weight loss dietary supplement. In the present study, we investigated the effect of HCA-SX on inflammation, oxidative stress and insulin resistance in developing obese Zucker rats, an animal model of type II diabetes associated with inflammation and oxidative stress. Male Zucker rats (5-week old) were supplemented with vehicle (control) and HCA-SX in drinking water for 7 weeks. Oxidative stress markers, including malondialdehyde (MDA), protein carbonyl (DNPH), and protein tyrosine nitration (tyr-NO(2)) were measured in the liver and kidney tissues using biochemical and immunoblotting techniques. Compared to controls, the levels of MDA, DNPH and tyr-NO(2) were lower in the liver and kidney of HCA-SX-treated animals. Furthermore, the levels of C-reactive protein and interleukin-6, markers of inflammation measured by ELISA, were lower in the plasma of HCA-SX-supplemented animals compared to controls, as were levels of fasting plasma insulin, glucose, and triglycerides. Interestingly, insulin resistance did not develop in HCA-SX-supplemented rats. Food-intake and body weight gain was also lower in rats supplemented with HCA-SX compared to their control counterparts. These results suggest that HCA-SX supplementation in obese Zucker rats reduces food-intake, body weight gain, and also attenuates the increases in inflammation, oxidative stress, and insulin resistance observed in untreated animals. Therefore, HCA-SX may be used as an intervention to overcome obesity-related complications, including inflammation, oxidative stress, and insulin resistance.

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The inhibitory action of L-cysteine in isolated porcine irides is dependent on the endogenous production of H(2)S by cystathionine gamma-lyase and cystathionine beta-synthase. Furthermore, prostanoids and K(ATP) channels are involved in the inhibitory action of L-cysteine in this tissue.

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