Level of mRNA of orexin receptors of second type (ORXR2) in conditions of chronic alcoholation in structures of the rat brain

BACKGROUND: Orexin and its receptors are involved in the mechanisms of pathological craving for alcohol, but there is no unambiguous answer about the expression of the OX2R gene in the rat brain under conditions of alcohol addiction. AIM: The aim of this study was to determine the level of OX2R mRNA in brain structures in rats under conditions of prolonged alcoholization and during the period of abstinence. MATERIALS AND METHODS: Adult male Wistar rats were alcoholized with 15% ethanol as the only source of liquid for 6 months. The rats were decapitated after chronic alcoholization, as well as on the 1st and 7th days of alcohol withdrawal. Samples of brain structures (prefrontal cortex, hippocampus, ventral tegmental area) were frozen in liquid nitrogen and stored at 80C. Determination of the level of OX2R mRNA was carried out using the method of PCR-analysis. RESULTS: The level of ORXR2 gene expression significantly increased in the hippocampus on the 7th day of abstinence in relation to the group of intact animals and in relation to the group of chronically alcoholized rats. The level of OX2R mRNA in the prefrontal cortex and ventral tegmental area in animal groups of abstinence (1st and 7th days) did not change in relation to both alcohol and the intact animals. CONCLUSIONS: It is concluded that the orexin brain system may represent a new potential therapeutic target for the prevention of relapse in alcohol withdrawal. Together with the previously obtained data it was concluded that orexin receptor antagonists can be used to reduce the pathological craving for alcohol.