Expression of the mRNA of neurotrophins in brain regions of rats after spontaneous morphine withdrawal

Abstract

The expression of specific genes is an important factor of neuroplastic changes during the formation of opiate dependence. Neurotrophic factors participate in structural-functional modifications in CNS regions after opiate intoxication. Here, we studied the levels of mRNAs of the brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and insulin-like growth factor 1 (IGF1) in the frontal cortex, striatum, hippocampus, and midbrain after spontaneous morphine withdrawal in dependent rats. To induce physical dependence, morphine was injected intraperitoneally twice a day with increasing doses of 10–100 mg/kg for 6 days. The expression of mRNAs of BDNF, NGF, and IGF1 in the brain areas was estimated 40 hours after spontaneous morphine withdrawal using the real-time PCR method. We found that spontaneous morphine withdrawal induced an elevation of BDNF and IGF1 mRNAs in the frontal cortex. In the hippocampus and the midbrain only BDNF mRNA increased. The content of NGF mRNA did not change in all regions studied. We believe that changes in the expression of BDNF and IGF1 are involved in the mechanisms of neuroplastic modification during the formation of opiate dependence.