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Variants of the opioid receptors are the obvious candidates underlying addiction. The kappa opioid receptor (KOR) system seems to play a role in stress responsivity, opiate withdrawal and responses to psycho-stimulants, inhibiting mesolimbic dopamine. KOR gene polymorphisms have been reported to contribute to predisposition to voluntary alcohol-drinking behavior in experimental animals. In humans, the 36G > T single nucleotide polymorphism (SNP) on KOR gene, that was recently identified, has been found associate with substance dependence, with inconclusive findings. In the present study, 106 heroin addicts (West European, Caucasians) and 70 healthy control subjects matched for race and gender, with no history of substance use disorder, have been genotyped. The frequency of KOR 36G > T SNP was significantly higher among heroin-dependent individuals compared with control subjects (Fisher's exact = 0.044; Pearson chi(2) = 4.2734, P = 0.039; likelihood ratio chi(2) tests = 4.6156, P = 0.032). Although KOR silent polymorphisms may apparently have no consequences on mRNA transcription, post-transcriptional mechanisms, such as mRNA stability, translation efficiency, and regulability may impair the function of kappa receptors system, with increased risk for substance use disorders. In specific, the neurobiological changes induced by mu-kappa opioid imbalance could underlie vulnerable personality traits and risk behavior.

An open randomized study was conducted to compare different treatments of alcoholism on ethanol intake, craving, and on biochemical measures of alcohol consumptions. Eighty-six alcoholics were abstinent for a mean of two weeks prior to random assignment to g-hydroxybutyrate (GHB, 50 mg/kg of body weight t.i.d), naltrexone (NTX, 50 mg/day) or disulfiram (DSF, 200 mg/ day) treatment for 12 months. All treatments were equally effective in reducing alcohol intake and in maintaining abstinence. In all patients, the treatments were able to reduce both craving and the altered biological markers of alcohol abuse. The maximum effects were observed in GHB-treated patients. The results of the present study suggest that GHB might act both as anticraving and cellular protector agent.

In 42 alcoholic inpatients we performed an open randomized study to compare the effects of diazepam and gamma-hydroxybutyrate (GHB) on the suppression of severe alcohol withdrawal syndrome and hypercortisolism. Both diazepam (.5 mg/kg bodyweight, q.i.d.) and GHB (50 mg/kg bodyweight, q.i.d.) were orally administered for three weeks. During all study period, GHB was more able than diazepam in reducing both withdrawal syndrome and hypercortisolism. These effects were evident during the first week of treatment and persisted throughout the study period. The results confirm a strict correlation between high levels of plasma cortisol and alcohol withdrawal symptoms and they show a slight superiority of GHB over diazepam in the suppression of both ethanol withdrawal and hypercortisolism. Taken together, our data suggest that GHB may act as potent anti-withdrawal agent in severe abstinent alcoholics.