ABSTRACT

Aim: Investigation of γ-secretase Inhibitor DAPT as a Potential Regulator of Notch Pathway in Rat‘s Neural Stem Cells after Spinal Cord Injury. Materials and Methods: A total of 120 male mice, aged between 3 and 4 months and weighing 30-35 g, were procured from the Experimental Animal Center of Southwest Medical University. The mice were kept in a controlled environment with a humidity range of 50-70% and a temperature range of 22-24°C, following a 12-hour light/dark cycle. The mice were allocated into three groups: Group 1, also known as the sham group, consisted of 40 mice; Group II, referred to as the I/R group, consisted of 40 mice that underwent I/R alone; and the DAPT group, which included 40 mice receiving DAPT therapy. The participants were organised into four distinct subgroups based on the duration of their respective periods: 1, 5, 10, and 15 days. Results: No discernible TUNEL-positive cells were seen in the spinal cord tissues of the sham group. In comparison to the sham group, a statistically significant increase in the number of TUNEL-positive cells was seen in mice subjected to spinal ischemia/reperfusion injury (P < 0.01). The results of the quantitative analysis revealed a statistically significant decrease in the number of TUNEL-positive neurons in the DAPT group compared to the I/R group (P < 0.05). The Notch1-positive signal exhibited cytoplasmic localization, whilst the nuclei were stained blue using 4′,6-diamidino-2-phenylin-dole (DAPI). In comparison to the sham group, a higher number of cells expressing Notch1 were seen in the spinal cord of the I/R group at each designated time point (P < 0.01). Following DAPT treatment, there was a significant reduction in the number of Notch1-positive cells as compared to the I/R group at various time intervals (P < 0.05). The western blot technique was used to quantify the amounts of Hes1 and Hes5 proteins in the cells of the spinal cord. In comparison to the sham group, the protein expression levels of Hes1 and Hes5 were shown to be significantly elevated in the I/R group (P < 0.01). The levels of IL-6 and TNF-α in the I/R group exhibited a progressive increase during the first 10-day period, followed by a subsequent drop from day 10 to day 15. Nevertheless, the levels of IL-6 and TNF-α were considerably suppressed after administration of DAPT (P < 0.05). Conclusion: In summary, DAPT demonstrates a beneficial effect on the improvement of neuronal structural damage in the spinal cord. The administration of DAPT has the potential to induce anti-inflammatory and anti-apoptotic effects via the inhibition of GFAP expression. The results of our study provide further theoretical support for the use of DAPT as a possible pharmacological intervention for spinal damage.