Alcohol use is extremely prevalent in Brazil and it is very harmful, creating problems not only for the users but for the whole society. Alcohol addiction is a complex phenomenon and involves multifactorial causes. Exposure to stressful situations during childhood can increase an individual's vulnerability to becoming an addict in adulthood. Although the relevance, the neurobiology of this interaction is not yet fully understood. Studies demonstrate the participation of the nociceptin system in mediating the ethanol seeking and taking behaviors consumption. It also demonstrated that the nociceptin system is involved in stress responses. Evidence shows that stress and alcohol consumption can alter the expression of nociceptin and its receptor through epigenetic changes. The present project aims to assess whether maternal separation stress may promote epigenetic changes in the nociceptin system and whether these changes may correlate with the increase in alcohol consumption in adult mice. From postnatal day (PND) 1 to 14, pups will be separated from the dam (maternal separation, MS) daily for 180 min or will be left undisturbed, only will be handled during cage cleaning (animal facility rearing, AFR). On PND 45, they will be assigned to operant oral alcohol self-administration. At the end of the third week of alcohol self-administration, a cannula will be implanted unilaterally into the lateral ventricle. Seven days after surgery, three additional self-administration sessions will be held. Twenty-four hours after the last session, distinct groups of animals will receive an intraventricular injection of sodium butyrate (histone deacetylation inhibitor) or 5-aza-2'-deoxycytidine (DNA demethylating agent), or vehicle. The next day, animals will be subjected to the alcohol binge protocol and soon after, the animals will be deeply anesthetized and the brain will be removed. Structures of the extended amygdala (nucleus accumbens, BNST and amygdala) will be dissected and processed for the analysis of nociceptin and its receptor expression through the RT-PCR and for the analysis of HDAC and DNMT enzyme activity, through enzymatic assays.
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