Modulation of DNA Methylation and Gene Expression in Rodent Cortical Neuroplasticity Pathways Exerts Rapid Antidepressant-Like Effects

• Published in: Molecular neurobiology 2021-02, Vol.58 (2), p.777-794
• Main Authors: Sales, Amanda J., Maciel, Izaque S., Suavinha, Angélica C. D. R., Joca, Sâmia R. L.
• Format: Article
• Language: English
• Subjects: Animals; Antidepressants; Antidepressive Agents - pharmacology; Behavior, Animal; Biomedical and Life Sciences; Biomedicine; Brain-derived neurotrophic factor; Brain-Derived Neurotrophic Factor - genetics; Brain-Derived Neurotrophic Factor - metabolism; Cell Biology; Deoxyribonucleic acid; DNA; DNA (Cytosine-5-)-Methyltransferases - antagonists & inhibitors; DNA (Cytosine-5-)-Methyltransferases - metabolism; DNA methylation; DNA Methylation - drug effects; DNA Methylation - genetics; Epigenetics; Gene expression; Gene Expression Regulation - drug effects; Helplessness, Learned; Learned helplessness; Male; Mental depression; Mood; N-Methyl-D-aspartic acid; Nervous system; Neurobiology; Neurology; Neuronal Plasticity - drug effects; Neuronal Plasticity - genetics; Neuroplasticity; Neurosciences; Prefrontal cortex; Prefrontal Cortex - physiology; Rapamycin; Rats; Rats, Wistar; Receptor, trkB - genetics; Receptor, trkB - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Serotonin S1 receptors; Signal Transduction - drug effects; Stress, Psychological - metabolism; Synaptic plasticity; TOR protein; TOR Serine-Threonine Kinases - metabolism; Transcription; TrkB receptors; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid
• ISSN: 0893-7648; 1559-1182
• DOI: 10.1007/s12035-020-02145-4

Background Stress increases DNA methylation, primarily a suppressive epigenetic mechanism catalyzed by DNA methyltransferases (DNMT), and decreases the expression of genes involved in neuronal plasticity and mood regulation. Despite chronic antidepressant treatment decreases stress-induced DNA methylation, it is not known whether inhibition of DNMT would convey rapid antidepressant-like effects. Aim This work tested such a hypothesis and evaluated whether a behavioral effect induced by DNMT inhibitors (DNMTi) corresponds with changes in DNA methylation and transcript levels in genes consistently associated with the neurobiology of depression and synaptic plasticity (BDNF, TrkB, 5-HT 1A , NMDA, and AMPA). Methods Male Wistar rats received intraperitoneal (i.p.) injection of two pharmacologically different DNMTi (5-AzaD 0.2 and 0.6 mg/kg or RG108 0.6 mg/kg) or vehicle (1 ml/kg), 1 h or 7 days before the learned helplessness test (LH). DNA methylation in target genes and the correspondent transcript levels were measured in the hippocampus (HPC) and prefrontal cortex (PFC) using meDIP-qPCR. In parallel separate groups, the antidepressant-like effect of 5-AzaD and RG108 was investigated in the forced swimming test (FST). The involvement of cortical BDNF-TrkB-mTOR pathways was assessed by intra-ventral medial PFC (vmPFC) injections of rapamycin (mTOR inhibitor), K252a (TrkB receptor antagonist), or vehicle (0.2 μl/side). Results We found that both 5-AzaD and RG108 acutely and 7 days before the test decreased escape failures in the LH. LH stress increased DNA methylation and decreased transcript levels of BDNF IV and TrkB in the PFC, effects that were not significantly attenuated by RG108 treatment. The systemic administration of 5-AzaD (0.2 mg/kg) and RG108 (0.2 mg/kg) induced an antidepressant-like effect in FST, which was, however, attenuated by TrkB and mTOR inhibition into the vmPFC. Conclusion These findings suggest that acute inhibition of stress-induced DNA methylation promotes rapid and sustained antidepressant effects associated with increased BDNF-TrkB-mTOR signaling in the PFC.