Influence of Surgical Trauma in the Nasal Cavity on the Expression of p53 Protein in the Hippocampus of Rats

The Relationship between p53-Positive Neurons and Dark Neurons in the Hippocampus of Rats after Surgical Interventions on the Nasal Septum

The study evaluates the dependence of p53 protein expression on the appearance of dark neurons (DNs) in the hippocampus in rats during experimental modeling of septoplasty. Septoplasty simulation was carried out on 15 sexually mature male Wistar rats. We studied histological sections of the hippocampus stained with Nissl toluidine blue and antibodies to the p53 protein. In the CA1 subfield, the number of p53-positive neurons significantly increased on the 2nd, 4th (p < 0.001) and 6th days (p < 0.05). In the dynamics, the peak of the growth of p53 protein expression in the cytoplasm of CA1 and CA2 neurons fell on the 2-4th day after the operation, and on the 6th day the number of these neurons decreased (p < 0.001). In the cytoplasm of CA3 neurons in all periods after surgery, an increase in the expression of the p53 protein as compared to the control group was noted. In the CA1 pyramidal layer, the number of DNs decreased on the 6th day (p < 0.001). In CA2, after 2 days, a minimum of DNs as compared with the 4th day (p < 0.001) was noted. In CA3, on the 4th day, there was a peak in DNs as compared with the rest of the days (p < 0.001). A positive strong association was found in all periods of assessment and in all subfields of the hippocampus between an increase in the number of dark and p53-positive neurons. The appearance of dark and p53-positive neurons in the hippocampal formation in rats after simulating septoplasty are typical responses of nervous tissue to stress. It is obvious that the expression of the p53 protein is associated with the basophilia of the cytoplasm of neurons, their morpho-functional state. Presumably, the p53 protein can trigger not only the activation of damaged neurons in the hippocampus but also play a neuroprotective role. Upcoming studies should determine the role of the p53 protein in the further fate of damaged neurons in the pyramidal layer and differentiate the mechanisms of its expression.

Changes in the Time-Domain of Heart Rate Variability and Corticosterone after Surgical Trauma to the Nasal Septum in Rats

The aim of the work was to study changes in the time range of heart rate variability (HRV) against the background of changes in the concentration of corticosterone in blood plasma in rats after surgical trauma to the nasal septum. Septoplasty was simulated in 30 mature male Wistar rats weighing 210-290 g. ECG was recorded with subsequent analysis of the time domain of HRV, as well as blood sampling to estimate changes in the concentration of corticosterone in the blood plasma was performed. As a result, SDNN significantly increased in comparison with the control on days 2 and 3 (p < 0.001) but decreased on days 4-5 (p < 0.001) and 6 (p < 0.01). rMSSD changed in waves with two irregular peaks on days 1 and 6. SDNN/rMSSD, in comparison with the 1st day of the postoperative period, increased on the 2nd day, continued to increase (p < 0.05), and then began to decrease on day 4 (p < 0.01). The total HRV power of was low throughout the postoperative period (p < 0.001), except for day 3, when it was equal to the control data. The increase in the total power index fell on day 3 after the operation (p <0.01), after which its decline was observed again. The concentration of corticosterone in the blood plasma in rats was significantly higher than before (p < 0.001). On postoperative day 2 to 4, its plateau was determined. Simulation of septoplasty leads to changes in the time range of HRV, an increase in the concentration of corticosterone in the blood plasma in rats with its maximum at the time of surgery and 24 h later, and the formation of a "plateau" on postoperative days 2 to 4, which coincides with the changes in HRV.