Beneficial effect of omega-3 fatty acids supplementation on leaky gut, inflammation and oxidative stress in propionic acid-induced autism in aged rats

This study examined the effects of omega-3 fatty acids supplementation on gut barrier integrity, systemic inflammation, neurotrans-mission and oxidative stress, in an aged rat model of propionic acid (PPA)-induced neurotoxicity. Twenty-four aged male rats were divided into four groups: control, omega-3, PPA and PPA + omega-3. Serum cytokines, tight-junction proteins (TJP1), dopamine, serotonin, short-chain fatty acids (SCFAs), oxidative stress markers, and histopathology of the brain and small intestine were evaluated. PPA exposure significantly increased tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) and reduced TJP1 expression, confirming gut barrier disruption and systemic inflammation. Omega-3 fatty acids supplementation selectively reduced IL-6 but did not reverse PPA-induced TNF-α elevation or oxidative stress. CLDN2 expression increased in PPA + omega-3 rats, suggesting a compensatory but incomplete barrier response. Dopamine, serotonin, and SCFA levels showed upward trends with supplementation but were not statistically significant. Histological analysis demonstrated partial preservation of neuronal and intestinal structure in the PPA + omega-3 group. Overall, omega-3 fatty acids exerted modest anti-inflammatory effects but failed to fully restore oxidative balance or barrier integrity in aged rats, suggesting that omega-3 fatty acids may be more effective as a preventive rather than restorative intervention in ageing-related gut-brain axis disruption.