Estradiol prevented intestinal ischemia and reperfusion-induced changes in intestinal permeability and motility in male rats

Abstract

Objectives: Ischemia and reperfusion (I/R) in the intestine could lead to severe endothelial injury, compromising intestinal motility. Reportedly, estradiol can control local and systemic inflammation induced by I/R injury. Thus, we investigated the effects of estradiol treatment on local repercussions in an intestinal I/R model.

Methods: Rats were subjected to ischemia via the occlusion of the superior mesenteric artery (45 min) followed by reperfusion (2h). Thirty minutes after ischemia induction (E30), 17β-estradiol (E2) was administered as a single dose (280 μg/kg, intravenous). Sham-operated animals were used as controls.

Results: I/R injury decreased intestinal motility and increased intestinal permeability, accompanied by reduced mesenteric endothelial nitric oxide synthase (eNOS) and endothelin (ET) protein expression. Additionally, the levels of serum injury markers and inflammatory mediators were elevated. Estradiol treatment improved intestinal motility, reduced intestinal permeability, and increased eNOS and ET expression. Levels of injury markers and inflammatory mediators were also reduced following estradiol treatment.

Conclusion: Collectively, our findings indicate that estradiol treatment can modulate the deleterious intestinal effects of I/R injury. Thus, estradiol mediates the improvement in gut barrier functions and prevents intestinal dysfunction, which may reduce the systemic inflammatory response.

Figure 1. Effect of intestinal I/R injury on the gastrointestinal transit (%). In rats with I/R injury, the superior mesenteric artery was clamped (45 min), followed by intestinal reperfusion (2h). Estradiol (180 µg/kg, i.v.) was administered 30 min after the induction of intestinal ischemia (E30). Sham-operated rats were used as controls. Data are expressed as the mean±standard error of the mean (SEM) from 6 animals. *p=0.011 compared with the sham group; ^γp=0.0457 versus intestinal I/R group. I/R, ischemia and reperfusion.

Figure 2. The effect of reperfusion in intestinal I/R on intestinal mucosal permeability. In rats with I/R injury, the superior mesenteric artery was clamped (45 min), followed by intestinal reperfusion (2h). Estradiol (180 µg/kg, i.v.) was administered 30 min after the induction of intestinal ischemia (E30). Sham-operated rats were used as controls. Data are expressed as the mean±standard error of the mean (SEM) from 6 animals. *p<0.0001 compared with sham; ^γp=0.0036 versus intestinal I/R. I/R, ischemia and reperfusion.

Figure 3. Quantification of eNOS (panel A) and endothelin-1 (panel B) expression in mesenteric vessels. In rats with I/R injury, the superior mesenteric artery was clamped (45 min), followed by intestinal reperfusion (2h). Estradiol (180 µg/kg, i.v.) was administered 30 min after induction of intestinal ischemia (E30). Sham-operated rats were used as control. Data are expressed as the mean±standard error of the mean (SEM) from 4 animals/group (2 tissue sections/animal). Panel A: *p=0.0026 compared with the sham group; ^γp<0.0001 compared to intestinal I/R. Panel B: *p<0.0001 versus sham group; ^γp<0.0001 versus intestinal I/R. eNOS, endothelial nitric oxide synthase; I/R, ischemia and reperfusion.

Figure 4. Immunohistochemistry analysis of the expression of endothelial nitric oxide synthase (eNOS) and endothelin (ET-1) in mesenteric vessels. Original magnification, ×40 for all images. In rats with I/R injury, the superior mesenteric artery was clamped (45 min), followed by intestinal reperfusion (2h). Estradiol (180 µg/kg, i.v.) was administered 30 min after the induction of intestinal ischemia (E30). Sham-operated rats were used as controls. I/R, ischemia and reperfusion.

Figure 5. Serum concentrations of lactate dehydrogenase (Panel A) and alkaline phosphatase activity. (Panel B). A group of rats had their superior mesenteric arteries clamped (45 min), followed by intestinal reperfusion (2h). Estradiol (180 µg/kg, i.v.) was administered 30 min after induction of intestinal ischemia (E30). Sham-operated rats were used as control. Data are expressed as the mean±standard error of the mean (SEM) from 8 animals. Panel A: *p=0.0081 compared with sham; ^γp=0.0066 compared with I/R. Panel B: ^γp=0.0088 compared with I/R. I/R, ischemia and reperfusion.

Figure 6. Effects of intestinal I/R injury and estradiol treatment on the serum levels of VEGF (panel A), IP-10 (panel B), TNFα (panel C), IL-10 (panel D), IL-1β (panel D), and IL-6 (panel E). In I/R injury rats, the superior mesenteric artery was clamped (45 min), followed by intestinal reperfusion (2h). Estradiol (180 µg/kg, i.v.) was administered 30 min after induction of intestinal ischemia (E30). Sham-operated rats were used as controls. Data are expressed as the mean±standard error of the mean (SEM) from 8 animals. *p≤0.05 compared with sham; ^γp≤0.05 compared with I/R. I/R, ischemia and reperfusion; VEGF, vascular endothelial growth factor; IP-10, inducible-protein-10 IL-10, interleukin 10; IL-1β, interleukin-1β; TNFα, tumor necrosis factor-alpha.