PPARA and opioid use disorder: Peroxisome proliferator-activated receptor-alpha (PPAR-α) is known to regulate cellular inflammatory response [20,21], and polyphenols, such as resveratrol, quercetin, magnolol, and β-catechin, found in many different plants [22,23,24,25], possess immune-modulatory properties, likely through the activation of PPAR-α [26,27,28,29], and their potential efficacy for treating opioid use disorder seems to be promising.