Risperidone Induced DNA Methylation Changes in Dopamine Receptor and Stathmin Genes in Mice Exposed to Social Defeat Stress

Objective@#Understanding complex epigenetic mechanisms is necessary to fully elucidate the effects of antipsychotic drug. This study investigated DNA methylation and mRNA expression levels of dopamine D2 and D1 receptor (Drd2 and Drd1, respectively), nuclear receptor subfamily 3, group C, member 1 (Nr3c1) and stathmin 1 (Stmn1) in brain regions of mice exposed to social defeat stress (SDS) and effects of risperidone on altered methylation and mRNA expression levels induced by SDS. @*Methods@#Following SDS for 10 days, risperidone (0.2 mg/kg) or vehicle was administered to adult mice for 7 days. Brain tissues from the prefrontal cortex (PFC), hippocampus (HIP) and amygdala (AMY) were processed to measure methylation and mRNA levels of Drd2, Drd1, Nr3c1 and Stmn1 using pyrosequencing and real time-polymerase chain reaction. @*Results@#We found altered methylation status of Nr3c1 and Stmn1 in the HIP and AMY of mice exposed to SDS. These changes were reversed by risperidone treatment. In addition, different methylation patterns of Drd2 and Drd1 in the PFC and AMY between defeated and control mice were identified with risperidone treatment. @*Conclusion@#These findings suggest that risperidone can cause epigenetic changes in Drd2, Drd1, Nr3c1 and Stmn1 in defeated mice. These changes could be epigenetic mechanisms underlying antipsychotic efficacy.

Impact of Social Defeat Stress on DNA Methylation in Drd2, Nr3c1, and Stmn1 in Wild-type and Stmn1 Knock-out Mice

Objective@#Epigenetic profiles can be modified by stress. Dopamine receptor D2 (Drd2), glucocorticoid receptor gene (Nr3c1) and Stathmin 1 (Stmn1) genes are all implicated in adaptation to stress. The aim of study is to investigate impact of social defeat on DNA methylation in Drd2, Nr3c1, and Stmn1 in wild-type (WT) and Stmn1 knock-out (KO) mice. @*Methods@#The WT and Stmn1 KO mice were subjected to chronic social defeat. Brain tissues of the prefrontal cortex (PFC), amygdala (AMY) and hippocampus (HIP) were obtained. We measured DNA methylation levels of the Drd2, Nr3c1, and Stmn1 genes in the PFC, AMY, and HIP using pyrosequencing. @*Results@#In WT mice, social defeat stress did not induce any changes in Drd2 methylation, whereas significant hypermethylation occurred in Nr3c1 and Stmn1 in the susceptible and unsusceptible groups, respectively, compared to the control group. The methylation responses in the Stmn1 KO mice differed from those seen in the WT mice, such that hypermethylation was evident in all three genes in the susceptible and unsusceptible groups compared to control group. Comparison of the Stmn1 KO and WT mice revealed the same pattern of hypermethylation for all three genes. @*Conclusion@#Social defeat stress induced different epigenetic modifications in three genes among control, unsusceptible, and susceptible groups of WT and Stmn1 KO mice. In particular, hypermethylation of Nr3c1 in the HIP of the susceptible group, and of Stmn1 in the AMY of the unsusceptible group in WT mice, could serve as epigenetic biomarkers of stress susceptibility and stress resilience, respectively.

A role for endocannabinoids in acute stress-induced suppression of the hypothalamic-pituitary-gonadal axis in male rats / 대한생식의학회지

OBJECTIVE: Stress is known to be an inhibitor of the reproductive hypothalamic-pituitary-gonadal (HPG) axis. However, the neural and molecular connections between stress and reproduction are not yet understood. It is well established that in both humans and rodents, kisspeptin (encoded by the kiss1 gene) is a strong stimulator of the HPG axis. In the present study we hypothesized that endocannabinoids, an important neuromodulatory system in the brain, can act on the HPG axis at the level of kiss1 expression to inhibit reproductive function under stress. METHODS: Adult male Wistar rats were unilaterally implanted with an intracerebroventricular cannula. Afterwards, the animals were exposed to immobilization stress, with or without the presence of the cannabinoid CB1 receptor antagonist AM251 (1 microg/rat). Blood samples were collected through a retro-orbital plexus puncture before and after stress. Five hours after the stress, brain tissue was collected for reverse transcriptase-quantitative polymerase chain reaction measurements of kiss1 mRNA. RESULTS: Immobilization stress (1 hour) resulted in a decrease in the serum luteinizing hormone concentration. Additionally, kiss1 gene expression was decreased in key hypothalamic nuclei that regulate gonadotrophin secretion, the medial preoptic area (mPOA), and to some extent the arcuate nucleus (ARC). A single central administration of AM251 was effective in blocking these inhibitory responses. CONCLUSION: These findings suggest that endocannabinoids mediate, at least in part, immobilization stress-induced inhibition of the reproductive system. Our data suggest that the connection between immobilization stress and the HPG axis is kiss1 expression in the mPOA rather than the ARC.