EFFECTS OF GLYCYL-L-GLUTAMINE ON CELL DEATH AND INFLAMMATORY PARAMETERS IN A RAT CORTICAL BRAIN SLICE OXYGEN-GLUCOSE DEPRIVATION/REOXYGENATION (OGD/R) MODEL

Objective: Ischemia-reperfusion (I/R) injury occurs when cerebral blood flow is restored to tissue after ischemia, triggering cell death and inflammatory responses. Therefore, there is a need to develop effective neuroprotective strategies. Glycyl-L-glutamine (Gly-Gln) is an endogenous dipeptide synthesized following the metabolism of β-endorphin1-31. This study aimed to investigate the effects of Gly-Gln on inflammatory parameters (IL-1β, IL-10), ferroptosis marker glutathione peroxidase-4 (GPX4), and the intracellular signal transduction transforming growth factor-β–activated kinase-1 (TAK1) levels in an in-vitro cortical brain slice I/R model.
Method: In this study, cortical brain slices obtained from male Wistar Albino rats (200-250 g) were used. The groups: Control, IR, and IR+Gly-Gln (n=5 in each group). The slices were subjected to a protocol consisting of 60-minutes of equilibration, 30-minutes of ischemia, and 30-minutes of reperfusion. The IR+Gly-Gln group received 2000 µM concentration of Gly-Gln. Tissue viability was assessed using TTC staining; IL-1β, IL-10, GPX4, and TAK1 levels were measured using the ELISA method.
Results: Tissue viability significantly increased in the I/R+Gly-Gln group compared to the I/R group (p<0.0001). When compared to the I/R group, IL-1β levels decreased in the I/R+Gly-Gln group (p=0.0007), while GPX4 levels significantly increased (p=0.03). When compared to the I/R group, no significant difference was found between the groups in terms of IL-10 and TAK1 levels.
Conclusion: Gly-Gln improved the viability of tissue damaged by I/R. This effect may be mediated by suppressing IL-1β-mediated inflammatory responses and enhancing antioxidant defense by suppressing GPX4-mediated ferroptosis. These findings suggest that Gly-Gln may be a potential neuroprotective agent against cerebral I/R.