Ketamine and imipramine in the nucleus accumbens regulate histone deacetylation induced by maternal deprivation and are critical for associated behaviors

Epigenetic and epistatic interactions between serotonin transporter and brain-derived neurotrophic factor genetic polymorphism: insights in depression

Epidemiological studies have shown significant results in the interaction between the functions of brain-derived neurotrophic factor (BDNF) and 5-HT in mood disorders, such as major depressive disorder (MDD). The latest research has provided convincing evidence that gene transcription of these molecules is a target for epigenetic changes, triggered by stressful stimuli that starts in early childhood and continues throughout life, which are subsequently translated into structural and functional phenotypes culminating in depressive disorders. The short variants of 5-HTTLPR and BDNF-Met are seen as forms which are predisposed to epigenetic aberrations, which leads individuals to a susceptibility to environmental adversities, especially when subjected to stress in early life. Moreover, the polymorphic variants also feature epistatic interactions in directing the functional mechanisms elicited by stress and underlying the onset of depressive disorders. Also emphasized are works which show some mediators between stress and epigenetic changes of the 5-HTT and BDNF genes, such as the hypothalamic-pituitary-adrenal (HPA) axis and the cAMP response element-binding protein (CREB), which is a cellular transcription factor. Both the HPA axis and CREB are also involved in epistatic interactions between polymorphic variants of 5-HTTLPR and Val66Met. This review highlights some research studying changes in the epigenetic patterns intrinsic to genes of 5-HTT and BDNF, which are related to lifelong environmental adversities, which in turn increases the risks of developing MDD.

Evaluation of inhibitory effect of recreational drugs on dopaminergic terminal neuron by PET and whole-body autoradiography

There is little investigation for the functional roles of peripheral dopamine. [¹⁸F]FDOPA has been used in cancer imaging (i.e., neuroendocrine and tumors pancreatic tumors) and neuroimaging (i.e., Parkinson's disease and Huntington's disease). Here, we accessed side effects of recreational drugs such as ketamine, cocaine, and methamphetamine on dopamine neurons in peripheral organs by using positron emission tomography (PET) imaging and quantitative whole-body autoradiography (QWBAR) with [¹⁸F]FDOPA. The images were applied for the measurement of specific binding ratios (SBRs) of striatum with the cerebellum as the reference region. Clear striatal [¹⁸F]FDOPA-derived radioactivity was observed. Moderate level of radiotracer accumulation was presented in the mucosal layers of the stomach and small intestine. The medulla layers of kidney had higher radioactivity than that of the cortex. Blocking images markedly eliminated the specific binding of [¹⁸F]FDOPA in the striatum and in peripheral organs such as stomachs, intestines, and kidney. Ketamine showed the highest inhibitory effect on striatal [¹⁸F]FDOPA-derived radioactivity followed by cocaine and methamphetamine. The current results demonstrated a useful crossing-validating tool that enhances the capability of [¹⁸F]FDOPA for further investigations of the alteration of dopaminergic neurons in the brain disorder or cancer diseases in peripheral tissues.

Environmental alterations of epigenetics prior to the birth

The etiology of many brain diseases remains allusive to date after intensive investigation of genomic background and symptomatology from the day of birth. Emerging evidences indicate that a third factor, epigenetics prior to the birth, can exert profound influence on the development and functioning of the brain and over many neurodevelopmental syndromes. This chapter reviews how aversive environmental exposure to parents might predispose or increase vulnerability of offspring to neurodevelopmental deficit through alteration of epigenetics. These epigenetic altering environmental factors will be discussed in the category of addictive agents, nutrition or diet, prescriptive medicine, environmental pollutant, and stress. Epigenetic alterations induced by these aversive environmental factors cover all aspects of epigenetics including DNA methylation, histone modification, noncoding RNA, and chromatin modification. Next, the mechanisms how these environmental inputs influence epigenetics will be discussed. Finally, how environmentally altered epigenetic marks affect neurodevelopment is exemplified by the alcohol-induced fetal alcohol syndrome. It is hoped that a thorough understanding of the nature of prenatal epigenetic inputs will enable researchers with a clear vision to better unravel neurodevelopmental deficit, late-onset neuropsychiatric diseases, or idiosyncratic mental disorders.