Orexin A expression and promoter methylation in patients with alcohol dependence comparing acute and protracted withdrawal

Abstract

The orexins (hypocretins) are neuropeptides deriving from the lateral hypothalamus and may be of importance within the context of drug craving, withdrawal, and relapse. Therefore, the orexin A expression and promoter methylation in peripheral blood cells of 68 patients (41 male and 27 female patients at three different time points during withdrawal and 27 patients during stationary dehabituation therapy) suffering from alcohol dependence were assessed by quantitative reverse transcription-polymerase chain reaction and bisulfite sequencing. There was a statistically significant difference of orexin A expression between the three time points of withdrawal and long-term (LT) abstinence (F=4.16, P=.011). This difference was most prominent in comparison with LT abstinence (t=-3.08, P=.0032). Expression was significantly associated with the severity of withdrawal symptoms measured with the Withdrawal Syndrome Scale for Alcohol and Related Psychoactive Drugs (WSA) (t=2.17, P=.0356). The stronger the withdrawal symptoms, the lower the orexin A expression (F=4.69, P=.036). Body mass index (t=2.15, P=.041), the severity of withdrawal measured with the WSA (t=2.595, P=.0133), craving measured either by the Obsessive Compulsive Drinking Scale (t=2.77, P=.0085) or the Lübecker Craving Questionnaire (t=-2.23, P=.0314) had a significant influence on orexin A expression taking into account mean methylation of the CpG island of the orexin A promoter during withdrawal. Orexin A may be a possible candidate to further elucidate mechanisms of alcohol withdrawal taking into account energy homoeostasis in the circuit of reward and motivation.