NITRIC OXIDE METABOLISM IN RAT SMALL INTESTINE TISSUES FOLLOWING SURGICAL TRAUMA REPRODUCED IN EXPERIMENTAL MODEL OF POSTTRAUMATIC STRESS DISORDER

The article investigates the parameters of the nitric oxide (NO) system in the small intestine tissues of rats subjected to surgical trauma within an experimental model of post-traumatic stress disorder (PTSD). The study involved 42 white Wistar rats weighing 210-230 g, divided into 6 groups: Group 1 comprised intact animals, Group 2 included animals with the PTSD induced through single-prolonged stress (SPS), Group 3 consisted of rats subjected to a sham surgical operation, Group 4 comprised animals undergoing laparotomy, Group 5 involved rats undergoing a sham surgical operation following SPS, and Group 6 included animals undergoing laparotomy under modeled SPS. Nitric oxide synthase (NOS) activity in small intestine homogenates was assessed using spectrophotometric methods; peroxynitrite formation was determined by analyzing the content of peroxynitrite of alkali and alkaline earth metals. The study has demonstrated the SPS results in evident signs of nitrosative stress in the small intestine tissues of rats: it enhances NOS activity by activating the inducible isoform, reduces the constitutive NOS activity and coupling, and elevates the concentration of peroxynitrites of alkali and alkaline-earth metals. On the 7th day following laparotomy under PTSD modelling, nitrosative stress indicators in the small intestine tissues such as total and inducible NOS activity, as well as peroxynitrite concentrations of alkaline and alkaline-earth metals, significantly surpassed their levels following a single laparotomy under simulated single prolonged stress.