Endogenous bacteria-triggered inducible nitric oxide synthase activation protects the ovariectomized rat stomach

The role of sex hormones in the intestinal injury after brain death using a surgical menopause model in rats

Among transplantable organs, the intestine is one of the most challenging organs to transplant. While there is considerable research on the effects of brain death (BD), little is known about the specific intestinal changes that occur, particularly in females. Here we investigated the role of female sex hormones in the BD-induced intestinal inflammation, using an ovariectomy (OVx) model for sex hormones depletion. Wistar rats (female) were divided into four experimental groups: Control non-OVx - non-manipulated; Control-OVx -ovariectomized; BD non-OVx - animals submitted to BD (6h); BD-OVx -ovariectomized animals submitted to BD. OVx was performed 10 days before BD induction. non-OVx groups were chosen during proestrus phase (heat period). Inflammatory mediators and white blood cell count were quantified in the blood. Intestine tissue was sampled for histopathological analysis, myeloperoxidase (MPO) activity, Evans blue dye extravasation assay and immunohistochemistry. Results show higher intestinal injury in BD-OVx than BD non-OVx animals, presenting reduced crypt depth and increased serum inflammatory mediators. Independently from the previous hormonal status, BD increased intestinal inflammation, with higher leukocyte infiltration, MPO activity, ICAM-1 expression, and higher serum MIP-1α. In summary, BD modulates intestinal inflammation by increasing leukocyte mobilization. Whereas OVx, and its consequences on the female hormonal profile, influences homeostasis and BD-induced inflammation, increasing inflammatory mediators and altering intestinal morphology.

Endotoxemia-mediated induction of cardiac inducible nitric-oxide synthase expression accounts for the hypotensive effect of ethanol in female rats

We have recently shown that intragastric (i.g.) ethanol lowers blood pressure (BP) in conscious female rats via a reduction in cardiac output (CO). However, the mechanisms implicated in these hemodynamic effects of ethanol are not known. Therefore, we tested the hypothesis that ethanol-evoked endotoxemia mediates the reduction in CO via enhanced myocardial inducible nitric-oxide synthase (iNOS) expression. Immunoblot (myocardial iNOS), biochemical (plasma endotoxin and nitrite/nitrate), and integrative [BP, heart rate, CO, stroke volume (SV), and total peripheral resistance (TPR)] studies were conducted in conscious female rats that received i.g. ethanol (1 g/kg) in the absence or presence of 1400W (N-(3-[aminomethyl]benzyl) acetamidine) or ampicillin to selectively inhibit iNOS and to eliminate endogenous endotoxin, respectively. Ethanol-evoked hypotension coincided with reductions in CO and SV and increases in: 1) TPR, 2) plasma endotoxin and nitrite/nitrate, and 3) myocardial iNOS expression. These effects of ethanol were virtually abolished in rats pretreated with ampicillin (200 mg/kg/day for 2 days by gavage) or with 1400W (5 mg/kg i.p.) except for the increase in plasma endotoxin, which persisted in 1400W-pretreated rats. These findings yield insight into the mechanistic role of endotoxin-myocardial iNOS signaling in the cardiodepressant action of ethanol, which accounts for its hypotensive effect in conscious female rats.