OPRK1 and cocaine abuse: In search for a molecular pattern associated with altered response to cocaine we measured neuromodulators related to the HPA axis and hypothalamic peptides, namely corticosterone, proopiomelanocortin (POMC), β-endorphin, along with CART 55–102 levels in plasma, and mRNA levels for D2 dopaminergic receptor, κ-opioid receptor (KOR), orexin 1 receptor (OX1R), CART 55–102, and previously suggested markers of cocaine abuse: microRNA-124 (miRNA-124) and microRNA-137 (miRNA-137) levels, in the PFC [40–42].