CRH and nicotine dependence: Although the molecular mechanisms that contribute to nicotine dependence are poorly understood, the neuromodulatory role of nicotinic cholinergic system in the central nervous system is principally implicated for it.[6] Numerous other neural pathways and neurotransmitters, including GABA, serotonin, glutamate, noradrenaline, endogenous opioid, and corticotropin releasing hormone, have also been shown to play a role in nicotine dependence [Figure 1].[7]