Addition of caffeine to equine thawed sperm increases motility and decreases nitrite concentration.

The aim of this study was to improve the quality of frozen-thawed equine sperm by the addition of caffeine to it. Semen from nine stallions was frozen and different concentrations of caffeine (3, 5 and 7.5 mM) were added to frozen-thawed semen. The sperm kinetic parameters, membrane functionality and integrity, and acrosome integrity and spontaneous acrosome reacted sperm were evaluated with a computer-assisted sperm analysis, a hypoosmotic swelling test and epifluorescent microscopy, respectively. Nitrite and hydroperoxide concentrations of frozen-thawed semen were measured using spectrophotometry. Sperm fertility was evaluated by artificial insemination (AI) of 16 mares with thawed ejaculates (control and 5 mM caffeine-treated groups). Compared to that in the control, the addition of 5 mM caffeine induced an increase in sperm motility (38.9 ± 2.8 versus 32.6 ± 3.4%), and a decrease in nitrite concentration (11.4 ± 2.1 versus 12.8 ± 2.9 µM/µg protein, p < .05). Moreover, the pregnancy rate from AI in the caffeine group was significantly higher (62.5%) than that in the control group (12.5%). These data suggest that caffeine reduced the nitrite concentration and enhanced sperm motility in thawed equine sperm, thus increasing the fertility rate in mares inseminated with caffeine-treated equine semen.

Neuronal nitric oxide synthase-derived hydrogen peroxide effect in grafts used in human coronary bypass surgery.

Recently, H2O2 has been identified as the endothelium-dependent hyperpolarizing factor (EDHF), which mediates flow-induced dilation in human coronary arteries. Neuronal nitric oxide synthase (nNOS) is expressed in the cardiovascular system and, besides NO, generates H2O2 The role of nNOS-derived H2O2 in human vessels is so far unknown. The present study was aimed at investigating the relevance of nNOS/H2O2 signaling in the human internal mammary artery (IMA) and saphenous vein (SV), the major conduits used in coronary artery bypass grafting. In the IMA, but not in the SV, ACh (acetylcholine)-induced vasodilatation was decreased by selective nNOS inhibition with TRIM or Inhibitor 1, and by catalase, which specifically decomposes H2O2 Superoxide dismutase (SOD), which generates H2O2 from superoxide, decreased the vasodilator effect of ACh on SV. In the IMA, SOD diminished phenylephrine-induced contraction in endothelium-containing, but not in endothelium-denuded vessels. Importantly, while exogenous H2O2 produced vasodilatation in IMA, it constricted SV. ACh increased H2O2 production in both sets of vessels. In the IMA, the increase in H2O2 was inhibited by catalase and nNOS blockade. In SV, H2O2 production was abolished by catalase and reduced by nNOS inhibition. Immunofluorescence experiments showed the presence of nNOS in the vascular endothelium and smooth muscle cells of both the IMA and SV. Together, our results clearly show that H2O2 induced endothelium-dependent vascular relaxation in the IMA, whereas, in the SV, H2O2 was a vasoconstrictor. Thus, H2O2 produced in the coronary circulation may contribute to the susceptibility to accelerated atherosclerosis and progressive failure of the SV used as autogenous graft in coronary bypass surgery.

Experimental Periodontal Disease Triggers Coronary Endothelial Dysfunction in Middle-Aged Rats: Preventive Effect of a Prebiotic ß-Glucan.

This study was aimed to verify the hypothesis that periodontal disease contributes to endothelial dysfunction in the coronary arteries of middle-aged rats. Besides we evaluated the effects of a prebiotic (ß-glucan isolated from Saccharomyces cerevisiae) in preventing vascular dysfunction. The sample comprised young (sham and induced to periodontal disease) and middle-aged rats (sham, periodontal disease, sham-treated and periodontal disease-treated), at 12 and 57 weeks, respectively. The treated-groups received daily doses of ß-glucan (50 mg/kg) orally (gavage) for 4 weeks, and periodontal disease was induced in the last 2 weeks by ligature. A myograph system assessed vascular reactivity. The expression of endothelial nitric oxide synthase (eNOS), cyclooxygenase 1 (COX-1), COX-2, p47phox, gp91phox, NF-KB p65, p53, p21, and p16 was quantified by western blotting. Serum hydroperoxide production was measured by the ferrous oxidation-xylenol orange (FOX-2) assay method. Interleukin-1 beta (IL-1ß), IL-10, and tumor necrosis factor-alpha (TNF-α) levels were evaluated by spectroscopic ultraviolet-visible analysis. Periodontal disease in middle-aged rats was associated with reduced acetylcholine-induced relaxations of coronary artery rings affecting the endothelium-dependent hyperpolarization- and the nitric oxide-mediated relaxations. The endothelial dysfunction was related to eNOS downregulation, pronounced impairment of the EDH-mediated relaxation, increased IL-1ß and TNF-α proinflammatory cytokines, and also upregulation of NADPH oxidase and COXs, starting accumulate aging markers such as p53/p21 and the p16. Treatment with ß-glucan effectively reduced bone loss in periodontal disease and delayed endothelial dysfunction in the coronary artery. Our data show that yeast ß-glucan ingestion prevented oxidative stress and synthesis of proinflammatory marker and prevented eNOS reduction induced by periodontal disease in middle-aged rats. These results suggest that ß-glucan has a beneficial effect on the coronary vascular bed.

Sex differences in progesterone-induced relaxation in the coronary bed from normotensive rats.

Progesterone seems to play a role in cardiovascular physiology since its receptors are expressed on endothelial cells from both sexes of mammals. However, little is known about its role on the coronary circulation. Thus, this study aims to evaluate the effect of acute administration of progesterone on the coronary bed and the endothelial pathways involved in this action in normotensive rats of both sexes. A dose-response curve of progesterone (1-50 µmol/L) in isolated hearts using the Langendorff preparation was performed. Baseline coronary perfusion pressure (CPP) was determined, and the vasoactive effect of progesterone was evaluated before and after infusion with Nω-nitro-L-arginine methyl ester (L-NAME), indomethacin, catalase, and Tiron. The analysis of nitric oxide (NO) and superoxide anion (O2 · -) was performed by DAF-2DA and DHE, respectively. Female group showed higher CPP. Nevertheless, progesterone promoted a similar relaxing response in both sexes. The use of L-NAME increased vasodilatory response in both sexes. When indomethacin was used, only the males showed a reduced relaxing response, and in the combined inhibition with L-NAME, indomethacin, and catalase, or with the use of Tiron, only the females presented reduced responses. NO and O2 ·- production has increased in female group, while the male group has increased only NO production. Our results suggest that progesterone is able to modulate vascular reactivity in coronary vascular bed with a vasodilatory response in both sexes. These effects seem to be, at least in part, mediated by different endothelial pathways, involving NO and EDH pathways in females and NO and prostanoids pathways in males.

Effects of progesterone treatment on endothelium-dependent coronary relaxation in ovariectomized rats.

AIM: Although progesterone (P4) has a beneficial effect on the cardiovascular system, P4 actions on the coronary bed have not yet been fully elucidated. This study evaluated the effect of progesterone treatment on endothelium-dependent coronary vascular reactivity in Wistar rats. MAIN METHODS: Eight-week-old adult rats were divided into Sham, Ovariectomized (OVX), Ovariectomized and progesterone treated (OVX P4). The OVX P4 group received daily doses of progesterone (2 mg/kg/day). Vascular reactivity was assessed by a modified Langendorff technique. The intensity of eNOS, Akt, and gp91phox protein expression was quantified by Western blotting. Superoxide anion (O2●-) and hydrogen peroxide (H2O2) production was measured by dihydroethidium and 2',7'-dichlorofluorescein, respectively. KEY FINDINGS: Treatment with P4 was able to prevent the reduction in baseline coronary perfusion pressure induced by ovariectomy. We observed that endothelium-dependent coronary vasodilation was reduced in the OVX group and potentiated in the OVX P4 group. Following the inhibition of the nitric oxide (NO) pathway, the bradykinin-induced relaxing response was potentiated in the OVX P4 group. With regard to the combined inhibition of NO and prostanoids pathways, the OVX P4 group showed a greater relaxing response, similar to what was found upon individual inhibition of NO. After the combined inhibition of NO, prostanoids and epoxyeicosatrienoic acids' pathways, the vasodilatory response induced by BK was abolished in all groups. SIGNIFICANCE: Treatment with P4 prevented oxidative stress induced by ovariectomy. These results suggest that progesterone has a beneficial action on the coronary vascular bed.

Sex difference in GPER expression does not change vascular relaxation or reactive oxygen species generation in rat mesenteric resistance arteries.

AIM: An imbalance between antioxidant and pro-oxidant factors, with a predominance of the latter, characterises oxidative stress and is indicative of a loss of vascular function. The beneficial vascular effects of oestrogen may be related to its ability to stimulate the G protein-coupled oestrogen receptor (GPER) and produce antioxidant activity. This study evaluated the GPER-dependent relaxation response in the mesenteric resistance arteries of female and male rats and measured the contributions of pro-oxidant and antioxidant enzymes in this response. MAIN METHODS: The relaxation response was characterised in third-order mesenteric arteries using concentration-response curves of the selective GPER agonist G-1 (1 nM-10 µM), target protein levels were measured using Western blots, and vascular superoxide anion (O2-) and hydrogen peroxide (H2O2) levels were measured using dihydroethidium (DHE) and dichlorofluorescein (DCF) staining, respectively. KEY FINDINGS: The GPER agonist induced concentration-dependent vasorelaxation without showing differences between sexes. However, GPER expression was greater in male rats. No sex differences were detected in the expression of antioxidant proteins (catalase, SOD-1, and SOD-2). The basal vascular production of O2- and H2O2 was similar in the studied groups, and stimulation with G-1 maintained this response. SIGNIFICANCE: Together, our results show that the expression of GPER is greater in male mesenteric arteries, despite of the lack of a difference in vascular response. Nevertheless, antioxidant enzyme expression levels and the generation rates of pro-oxidants were similar between the studied groups. These results offer a new perspective for understanding GPER expression and functionality in resistance arteries.