As learn more mentioned earlier, global histone methylation of H3K9 is also regulated by cocaine and, in turn, alters behavioral responses to the drug. For example, inhibition of a particular H3K9 histone methyltransferase, KMT1C (G9a), whose expression is regulated in the NAc by chronic cocaine administration, potentiates behavioral responses to the drug.37

These findings are consistent with histone acetylation findings, since inhibition of H3K9 methylation would also be expected Inhibitors,research,lifescience,medical to enhance gene activity. Together, these data suggest that, in general, increases in gene expression potentiate behavioral sensitivity to drugs of abuse. As well, advances are being made in identifying the individual gene promoters where chronic cocaine induces Inhibitors,research,lifescience,medical alterations in H3K9 methylation and thereby regulates gene expression in the NAc.37 Overall, these findings implicate changes in histone acetylation, phosphorylation, and methylation in mediating expression changes in specific sets of genes that are crucial for controlling behavioral responses to drugs of abuse. Epigenetic mechanisms in depression

Depression is a chronic disorder characterized by many debilitating symptoms including dysphoria, anhedonia, Inhibitors,research,lifescience,medical sleep disturbances, and weight changes. Most people diagnosed with depression are prescribed some type of antidepressant medication, of which selective Inhibitors,research,lifescience,medical serotonin reuptake inhibitors (SSRIs) or mixed serotonin-norepinephrine reuptake inhibitors (SNRIs) are the most common. Unfortunately, less than 50% of patients exhibit a complete response to SSRIs, SNRIs, or related antidepressants, thus leaving a substantial portion of depressed patients with a chronic syndrome for which few effective clinical alternatives are available. Psychiatric Inhibitors,research,lifescience,medical research is thus focused on identifying new mechanisms that are involved in the pathogenesis and maintenance of depression, which may serve as novel targets for more effective therapeutics. One of the most challenging obstacles for depression

research has been the development of an animal model that accurately recapitulates human depression. While no model of can effectively model all aspects of human depression (eg, suicide), some of the major symptoms such as anhedonia and sleep and weight disturbances, and their reversal by antidepressant treatment, can be studied in rodents. The pathogenesis of depressed-like states is typically modeled in rodents by chronic exposure to stress.44 One such model, chronic social defeat stress, involves the repeated exposure of an experimental mouse to a series of aggressive mice over 10 days. Each day the stress begins as a brief physical encounter (typically 5 to 10 minutes) followed by a full day of sensory contact (eg, smell, sight) as the mice are separated by a screen.