The impact of dehydroepiandrosterone on indomethacin-induced gastric lesions in rats.

UNLABELLED: Gastric ulcer is a common gastrointestinal disease. One suggested mechanism is increased oxidative stress. Puplished data showed that dehydroepiandrosterone (DHEA) may limit oxidative stress and lipid peroxidation. OBJECTIVE: To investigate the protective effect of DHEA on indomethacin-induced gastric ulcers in rats. METHODS: Forty male rats were randomly divided into four groups: l) CONTROL GROUP: receive the vehicle, 2) DHEA-treated group, 3) Indomethacin-induced ulcer group and 4) DHEA pretreated (prior to indomethacin) group. At the end of the experiment, rats were killed and the gastric contents were collected to determine the pH and acid concentration. Gastric mucosa was examined macroscopically and then parts of the tissues were collected for histopathological examination. Other parts of the gastric mucosa were homogenized to measure the levels of lipid peroxidation and oxidative stress parameters. RESULTS: Indomethacin-treated rats showed increased gastric acidity, acid concentration and ulcer index as compared to control rats. This is confirmed by histopathological studies. DHEA pre-treatment proir to indomethacin administration ameliorated all changes seen in the ulcered group. CONCLUSION: DHEA has a protective effect against indomethacin-induced gastric ulcers through decreasing acid secretion, prevention of lipid peroxidation and improving endogenous gastric antioxidant system.

Effect of testosterone replacement therapy on cardiac performance and oxidative stress in orchidectomized rats.

AIM: To investigate the effects of testosterone on myocardial contractility, oxidative stress status and expression of sodium channel protein (Nav1.5) and inward rectifying K channels (Kir 2.x) in normal and orchidectomized (ORX) rats. METHODS: One hundred four rats were randomly assigned into four groups (n = 26, each) as follows: (i) untreated controls, (ii) testosterone treated, (iii) orchidectomized rats and (iv) orchidectomized, testosterone-treated rats. Treatments with the vehicle or testosterone were carried out for 12 weeks, three times per week. At the end of treatment, surface ECG, isolated heart, tissue oxidative stress and lipid peroxidation experiments were carried out on the cardiac tissues. Also, immunohistochemical examination for Nav1.5 and PCR detection of mRNA of Kir2.1, Kir2.2 and Kir2.4 subunits of K channels were carried out. RESULTS: Orchidectomy impaired cardiac contractile function parameters left ventricular developed pressure (LVDP) and the peaks of the positive and negative pressure derivatives (dP/dtmax and -dP/dtmax respectively), increased heart rate and prolonged QT and QTc intervals, elevated pro-oxidant state in rat's hearts and decreased the expression of Kir 2.1 but not Kir2.2, Kir 2.4 and Nav1.5 channels. Exogenous testosterone administration to orchidectomized rats restored heart contractility and shortened QT and QTc intervals to their normal values, ameliorated the generated pro-oxidant state and improved the expression of Nav1.5 and Kir2.1, but not Kir2.2 or Kir2.4 channels. CONCLUSION: Testosterone improved cardiac contractility and shortened QT and QTc intervals in ORX rats. An effect that might be dependent of reduction in oxidative stress and enhancement of Kir2.1 channels but independent of Nav1.5 channel protein.