Effect of morphine exposure on novel object memory of the offspring: The role of histone H3 and ΔFosB.

It has been demonstrated that alteration in histone acetylation in the regions of the brain involved in the reward which may have an important role in morphine addiction. It is well established that epigenetic changes prior to birth influence the function and development of the brain. The current study was designed to evaluate changes in novel object memory, histone acetylation and ΔFosB in the brain of the offspring of morphine-withdrawn parents. Male and female Wistar rats received morphine orally for 21 following days. After ten days of abstinent, they were prepared for mating. The male offspring of the first parturition were euthanized on postnatal days 5, 21, 30 and 60. The novel object recognition (NOR) test was performed on adult male offspring. The amount of acetylated histone H3 and ΔFosB were evaluated in the prefrontal cortex (PFC) and hippocampus using western blotting. Obtained results indicated that the discrimination index in the NOR test was decreased in the offspring of morphine-withdrawn parents as compared with morphine-naïve offspring. In addition, the level of acetylated histone H3 was decreased in the PFC and hippocampus in the offspring of morphine-withdrawn parents during lifetime (postnatal days 5, 21, 30 and 60). In the case of ΔFosB, it also decreased in these regions in the morphine-withdrawn offspring. These results demonstrated that parental morphine exposure affects NOR memory, and decreased the level of histone H3 acetylation and ΔFosB in the PFC and hippocampus. Taken together, the effect of morphine might be transmitted to the next generation even after stop consuming morphine.