Chronic aerobic exercise: Autoradiographic assessment of GABA(a) and mu-opioid receptor binding in adult rats

Exercise programs have shown great potential for both the prevention and treatment of substance use disorder (SUD). As exercise has been shown to have potent effects on physical and psychological health, it is reasonable to examine the mechanism of how exercise can be used as an adjunct treatment for addiction. The present study examined the effects of chronic aerobic (treadmill) exercise on both GABA(a) and mu-opioid receptor levels in the brains of male and female rats. GABA(a) receptor binding, measured by [³H] Flunitrazepam, was increased in the cingulate cortex following exercise, but only in females. Mu-opioid receptor expression, measured by [³H] ([D-Ala², N-MePhe⁴, Gly-ol]-enkephalin) (DAMGO), showed no effect of exercise while showing an effect of sex, with increased [³H] DAMGO binding in the brains of sedentary males compared to that of sedentary females. Our findings support the potential role for GABA(a) signaling in the cingulate cortex as part of the mechanism of action of aerobic exercise. These data, along with prior reports, aid our understanding of the neurochemical impact and mechanism of chronic aerobic exercise on neuropsychiatric disease, particularly regarding addiction.