Nitric oxide mediates an inflammatory effect of Escherichia coli in the porcine uterus
Treść / Zawartość
The purpose of this study was to determine whether inflammatory changes in uterus caused by Escherichia coli are associated with changes in nitric oxide (NO) production. Therefore, the activity of NADPH-diaphorase (NADPH-d), a histochemical marker for nitric oxide synthase (NOS), localization of inducible isoform of NOS (iNOS) and tissue content of nitrite were studied in the uterine structures after inoculation of Escherichia coli into the uterus in gilts. Twelve sexually matured gilts with controlled estrous cycle were used. The animals were laparotomized on the 2nd day of the estrous cycle and polyvinyl cannulas were inserted into the uterine horns to infuse saline or Escherichia coli. In the group I (control; n=6), 25 ml of saline was infused into each uterine horn on the 4,h day of the estrous cycle. At the same time, 25 ml of Escherichia coli (strain 025:K23/α/:Hl) suspension, containing 107 colony forming units/ml was inoculated into each uterine horn of the treated gilts (group II; n=6). The middle part of the uterine horn was collected on the 14th day of the next estrous cycle immediately after slaughter. Cryostat sections from paraformaldehyde fixed tissues were stained histochemically to study the activity of NADPH-d and immunohistochemi- cally to investigate the distribution of iNOS. Optical density was assessed to evaluate the intensity of the histochemical reaction. Nitrite content was measured spectrophotometrically. In the Escherichia coli-treated gilts, the activitý of NADPH-d in the luminal epithelium and in external parts of excretory ducts of uterine glands was higher (P < 0.001) as compared to that in the control animals. In the secretory part of the uterine glands the activity of this enzyme was similar in both groups of the gilts. In the gilts that received Escherichia coli, the histochemical reaction of NADPH-d in endometrial blood vessels was stronger than that found in the control animals. Immunoreactivity for iNOS in the luminal epithelium, in external parts of excretory ducts of uterine glands and in vascular endothelial cells was stronger in the Escherichia coli-treated gilts as compared to that observed in the control animals. Only weak or no immunoreactivity was found in the secretory part of the uterine glands in both groups of the gilts. After Escherichia coli inoculation, nitrite content in the uterine tissues was higher (P < 0.05) than that determined in the controls. Our study has revealed that infusion of Escherichia coli into the porcine uterus induces the activity of NADPH-d, iNOS and increases the tissue content of nitrite in this organ. The data obtained indicate that NO can mediate an inflammatory effect of Escherichia coli in the uterus.