Flaxseed Oil Mitigates Stress-Induced Immunoreactivity Loss of Midbrain Tyrosine Hydroxylase-Positive neurons caused by High- intensity exercise training

Exercise training exerts complex effects on brain plasticity, particularly in dopaminergic midbrain regions, yet its interaction with neuroprotective compounds remains underexplored. Plant-derived omega-3 fatty acids, such as alpha-linolenic acid in flaxseed oil, possess antioxidant and neuroprotective properties, that may buffer exercise-induced stress on neuron-glia dynamics. This study evaluated the effects of flaxseed oil supplementation on the morphology, density, and protein expression of dopaminergic neurons and astrocytes in the midbrain under high-intensity exercise conditions. Male Wistar rats were assigned to four groups: sedentary (CN), sedentary with flaxseed oil (OLSE), exercise (EX), and exercise with flaxseed oil (OLEX). Mesencephalic tissue was analyzed by immunohistochemistry for tyrosine hydroxylase (TH), glial fibrillary acidic protein (GFAP), and calbindin, assessing morphological changes, optical density, and cell density. Morphometric analysis revealed significant increases in TH + neuronal soma area and perimeter in the OLEX group compared to EX and CN (p < 0.05), without significant morphological changes observed in the ventral tegmental area (VTA) neurons. The density of TH + neurons and GFAP + astrocytes were similar across groups; however, optical density analysis showed significant differences in TH, GFAP, and calbindin expression (p < 0.05), particularly between OLEX and EX. These findings suggest that flaxseed oil alters protein expression and neuronal morphology in a region-specific manner. This study highlights the potential of flaxseed oil as a bioactive compound in preserving midbrain integrity, offering new insights into its therapeutic applications for neuroprotection under physiological stress, potentially mitigating exercise-induced stress on the dopaminergic regions.