α-Ketoglutarate Is a Circulatory Exercise Factor That Promotes Learning and Memory Recall and Has Antidepressant Properties.

Background: Depression poses a significant societal burden, necessitating effective treatment options. Conventional approaches often fall short, highlighting the need for alternatives. Exercise has emerged as a promising nonpharmacological strategy for improving mental health outcomes. Exercise promotes memory recall and alleviates depression by modulating BDNF (brain-derived neurotrophic factor) expression. The effects of exercise on BDNF are influenced by circulatory metabolites known as exercise factors. Methods: Associative and spatial memory were evaluated in mice receiving α-ketoglutarate (aKG) and in exercise mice given a glutaminase inhibitor. To prevent and treat depression-like behaviors, male mice underwent daily defeat sessions by a CD1 aggressor for 10 days. Behavior was assessed on day 11 using social interaction and open-field tests. Mice received aKG for 5 days prior to the stress paradigm or as treatment for 14 days following the stress paradigm, after which social behavior was reassessed. BDNF signaling was examined via Western blots. Results: aKG was identified as a metabolite released into the bloodstream following exercise in male mice. aKG was shown to mediate the positive effects of exercise on spatial learning and memory formation. aKG was also shown to have prophylactic and antidepressant effects in a chronic social defeat stress model of depression. Conclusions: aKG acts as a prophylactic and antidepressant to effectively counteract social avoidance behaviors by modulating BDNF levels in the hippocampus and nucleus accumbens.