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

Dopaminergic afferents from the mesencephalic areas, such as ventral tegmental area (VTA), synapse with the gamma-aminobutyric acid (GABA)-ergic interneurons in the prefrontal cortex (PFC). Pharmacological and electrophysiological data show that the reinforcement, the dependence-producing properties, as well as the psychopharmacologic effects of nicotine depend to a great extent on activation of nicotinic receptors within the mesolimbocortical dopaminergic projection. To explore further the relationship between the mesencephalic dopaminergic neurons and PFC GABAergic neurons, we investigated the effects of nicotine and passive exposure to cigarette smoke on the regulation of tyrosine hydroxylase (TH) in VTA and substantia nigra (SNC) and dopamine (DA) D1 receptor levels in nucleus accumbens (NAc) and caudate-putamen (CPu). Also, the simultaneous changes in GABAB receptors mRNAs in the PFC were studied. The results showed that chronic nicotine and smoking treatment differentially changed the levels of TH protein in VTA and SNC and DA D1 receptor levels in Nac and CPu. GABAB1 and GABAB2 receptor mRNA levels also showed different change patterns. Ten and thirty minutes of smoke exposure increased GABAB1 receptor mRNA to a greater extent than that of GABAB2, whereas GABAB2 was greatly enhanced after 1 hr of smoke exposure. The TH levels in VTA were closely related to DA D1 receptor levels in NAc and with GABAB receptor mRNA changes in PFC. These results suggest that the mesolimbic pathway and GABAB receptor mRNA in PFC are modulated by nicotine and cigarette smoke, implying an important role in nicotine's psychopharmacological effects.

Chronic social defeat stress increases dopamine D2 receptor dimerization in the prefrontal cortex of adult mice

Abnormal DNA methylation has been observed in promoter regions of a number of genes in human alcoholics. It is unclear whether DNA methylation changes in alcoholics result directly from alcohol consumption or predated the occurrence of alcohol abuse or dependence and whether altered DNA methylation influences gene expression. We investigated ethanol (EtOH)-induced DNA methylation changes in mouse serotonin receptor 3a gene (Htr3a). A 5-day drinking-in-the-dark paradigm was applied to 28 male outbred CD-1 mice (15 EtOH-drinking and 13 water-drinking). The Sequenom MassARRAY approach was used to quantify methylation levels of 8 CpGs around Htr3a transcription start site in trunk blood and 9 brain regions (dorsomedial prefrontal cortex [DMPFC], ventromedial prefrontal cortex, ventral tegmental area, dorsolateral striatum, dorsomedial striatum [DMSTR], ventral striatum, amygdala, hippocampus [HIPPO], and cerebellum). DNA methylation differences between the 2 groups of mice (EtOH- and water-drinking) were analyzed using multivariate analysis of covariance with consideration of EtOH consumption amount. Expression levels of Htr3a in the DMSTR were measured by real-time PCR in 14 EtOH-drinking and 14 water-drinking male CD-1 mice. EtOH drinking increased methylation levels of specific Htr3a promoter CpGs in mouse blood (CpG-27: p = 0.028; CpG+54: p = 0.044) and HIPPO (CpG+151: p = 0.012) but reduced methylation levels of specific Htr3a promoter CpGs in mouse DMSTR (CpG-96: p = 0.020; CpG-27: p = 0.035) and DMPFC (CpG+138: p = 0.011; CpG+151: p = 0.040). Nevertheless, methylation levels of Htr3a promoter CpGs in 6 other brain regions were not significantly altered by EtOH consumption. Additionally, the expression level of Htr3a in the DMSTR was 1.43-fold higher in alcohol-drinking mice than in water-drinking mice (p = 0.044). Our findings indicate that alcohol consumption may induce tissue-specific DNA methylation changes and further suggest that Htr3a promoter methylation levels may be reversely correlated with Htr3a expression levels in specific brain regions such as DMSTR.

DNA (cytosine) methylation mechanism is another way through which plants respond to various cues including soil fertility amendments and abiotic stresses, and the mechanism has been used to infer some physiological, biochemical or adaptation processes. Despite numerous studies on global DNA methylation profiling in various crop species, however, researches on fresh corn (Zea mays L. saccharata or rugosa) remain largely unreported. The study aimed at investigating sulphur and chlorine induced DNA methylation changes in the fresh corn leaves of field-grown plants at the milk stage. Methylation sensitive amplification polymorphism (MSAP) technique was used to profile sulphur (S) and chlorine (Cl) induced DNA methylation patterns, levels and polymorphism alterations at the CCGG sites in fresh corn leaves of TDN21, JKN2000 and JKN928 hybrid cultivars. Twelve primer pairs used effectively detected 325 MSAP bands, exhibiting differentially methylated sites in the genomic DNA of all the three cultivars, with control showing higher (48.9-56.3%) type I bands as compared to sulphur (34.8-44.9%) and chlorine (40.9-47.4%) treatment samples. Consequently, total methylation levels were greater in S and Cl treatment samples than control; accounting for 43.7-59.7, 51.1-65.2 and 46.8-55.1% of total sites in TDN21, JKN2000 and JKN928, respectively. Full methylation of the internal cytosine was greater than hemi-methylation. Further, demethylation polymorphic loci significantly exceeded methylation polymorphic loci, being greater in S than Cl and control samples in all cultivars. Sulphur and chlorine have a profound influence on DNA methylation patterns and levels at the milk stage, principally by increasing the demethylation loci in the internal cytosine of the fresh corn genome. We speculate that these methylation alterations play an integral role in photosynthates assimilation and physiochemical pathways regulating quality parameters in kernels, as well as abiotic stress responses in fresh corn.

Retinal degeneration is a major cause of irreversible blindness. Stimulation with controlled low-level electrical fields, such as transcorneal electrical stimulation (TES), has recently been postulated as a therapeutic strategy. With promising results, there is a need for detailed molecular characterization of the therapeutic effects of TES. Controlled, non-invasive TES was delivered using a custom contact lens electrode to the retinas of Royal College of Surgeons (RCS) rats, a model of retinal degeneration. DNA methylation in the retina, brain and cell-free DNA in plasma was assessed by reduced representation bisulfite sequencing (RRBS) and gene expression by RNA sequencing. TES induced DNA methylation and gene expression changes implicated in neuroprotection in the retina of RCS rats. We devised an epigenomic-based retinal health score, derived from DNA methylation changes observed with disease progression in RCS rats, and showed that TES improved the epigenomic health of the retina. TES also induced DNA methylation changes in the superior colliculus: the brain which is involved in integrating visual signaling. Lastly, we demonstrated that TES-induced retinal DNA methylation changes were detectable in cell-free DNA derived from plasma. TES induced DNA methylation changes with therapeutic effects, which can be measured in circulation. Based on these changes, we were able to devise a liquid biopsy biomarker for retinal health. These findings shed light on the therapeutic potential and molecular underpinnings of TES, and provide a foundation for the further development of TES to improve the retinal health of patients with degenerative eye diseases.

During the transit through the oviduct, the early embryo initiates an extensive DNA methylation reprogramming of its genome. Given that these epigenetic modifications are susceptible to environmental factors, components present in the oviductal milieu could affect the DNA methylation marks of the developing embryo. The aim of this study was to examine if culture of bovine embryos with oviductal fluid (OF) can induce DNA methylation changes at specific genomic regions in the resulting blastocysts. In vitro produced zygotes were cultured in medium with 3 mg/mL bovine serum albumin (BSA) or 1.25% OF added at the one- to 16-cell stage (OF1-16), one- to 8-cell stage (OF1-8) or 8- to 16-cell stage (OF8-16), and then were cultured until Day 8 in medium with 3 mg/mL BSA. Genomic regions in four developmentally important genes (MTERF2, ABCA7, OLFM1, GMDS) and within LINE-1 retrotransposons were selected for methylation analysis by bisulfite sequencing on Day 7-8 blastocysts. Blastocysts derived from OF1-16 group showed lower CpG methylation levels in MTERF2 and ABCA7 compared with the BSA group. However, CpG sites within MTERF2, ABCA7 and OLFM1 showed higher methylation levels in groups OF1-8 and OF8-16 than in OF1-16. For LINE-1 elements, higher CpG methylation levels were observed in blastocysts from the OF1-16 group than in the other experimental groups. In correlation with the methylation changes observed, mRNA expression level of MTERF2 was increased, while LINE-1 showed a decreased expression in blastocysts from OF1-16 group. Our results suggest that embryos show transient sensitivity to OF at early stages, which is reflected by specific methylation changes at the blastocyst stage.

Emerging evidence indicates that persistent alcohol consumption escalates psychosocial trauma achieved by social defeat stress (SDS)-induced neurobiological changes and behavioral outcomes. Treatment with compounds with neuroprotective functions is believed to reverse ethanol (EtOH)-aggravated SDS-induced behavioral impairments. We investigated the outcomes of diosgenin treatment, a phytosteroidal sapogenin in mice co-exposed to repeated SDS and EtOH administration. During a period of 14days, SDS male mice were repeatedly administered EtOH (20%, 10mL/kg) orally from days 8-14 (n = 9). Within days 1-14, SDS mice fed with EtOH were simultaneously treated with diosgenin (25 and 50mg/kg) or fluoxetine (10mg/kg) by oral gavage. Locomotor, cognitive-, depressive-, and anxiety-like behaviors were assessed. Adrenal weight, serum glucose, and corticosterone levels were assayed. Brain markers of oxido-inflammatory, neurochemical levels, monoamine oxidase-B, and acetylcholinesterase activities were measured in the striatum, prefrontal cortex, and hippocampus. The anxiety-like behavior, depression, low stress resilience, social, and spatial/non-spatial memory decline exhibited by SDS mice exposed to repeated EtOH administration were alleviated by diosgenin (25 and 50mg/kg) and fluoxetine, illustrated by increased dopamine and serotonin concentrations and reduced monoamine oxidase-B and acetylcholinesterase activities in the prefrontal cortex, hippocampus, and striatum. Diosgenin attenuated SDS + EtOH interaction induced corticosterone release and adrenal hypertrophy, accompanied by reduced TNF-α, IL-6, malondialdehyde, and nitrite levels in the striatum, prefrontal cortex, and hippocampus. Diosgenin increased glutathione, superoxide dismutase, and catalase levels in SDS + EtOH-exposed mice. Our data suggest that diosgenin reverses SDS + EtOH interaction-induced behavioral changes via normalization of hypothalamic-pituitary-adrenal axis, neurochemical neurotransmissions, and inhibition of oxidative and inflammatory mediators in mice brains.

Intermittent social defeat stress enhances mesocorticolimbic ΔFosB/BDNF co-expression and persistently activates corticotegmental neurons: Implication for vulnerability to psychostimulants

Approaching the Molecular Pathology of Suicide

The lower levels of dopamine D2 receptor (D2R) in the striatum and the heightened levels of dopamine D2 receptor (D3R) in the midbrain have been linked to impulsive behavior and risky decision-making associated with drug dependence. While D3R has been considered a potential target for treating drug dependence, the connection between D3R in the prefrontal-striatal regions and maladaptive drug-related behaviors remains poorly understood. This study utilized two high-cost tasks to investigate perseverative reward seeking, specifically conflict-based approaching behavior and persistent responding behavior under a progesterone receptor (PR) procedure. Additionally, D2R and D3R levels in the medial prefrontal cortex (mPFC) and striatum were examined through Western blotting. After each task, male rats were divided into two subpopulations: high-approaching vs. low-approaching and high-responding vs. low-responding. Rats treated with morphine (MOR) exhibited a 3 fold increase in the likelihood of developing high-approaching or high-responding behaviors compared to drug-naïve rats. D2R expression was higher in the ventral striatum of morphine-treated, low-approaching rats than high-approaching rats, negatively correlating with approaching behaviors within the morphine-exposed group. After six consecutive PR sessions, D3R levels in the dorsal striatum differed significantly between morphine-treated, low-responding rats and morphine-treated, high-responding rats, negatively correlating with responding behaviors within the morphine-exposed group. An intriguing finding was the non-linear relationships, resembling an inverted U shape, observed between the level of D3R in the mPFC and reward-seeking behaviors, as revealed by both tasks. The elevated or relatively higher levels of D2R and D3R in the frontal-striatal regions may serve as protective factors for individuals abstaining from opioids, enabling them to control their reward-seeking behavior better.

M40 - Effect of Chronic Treatment With Psychiatric Medications Aripiprazole And Riluzole on Dna Methylation Profiles In The Rat Striatum And Prefrontal Cortex

Calorie restriction (CR) increases healthy life span and is accompanied by slowing or reversal of aging-associated DNA methylation (DNAm) changes in animal models. In the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIETM) human trial, we evaluated associations of CR and changes in whole-blood DNAm. CALERIETM randomized 220 healthy, nonobese adults in a 2:1 allocation to 2 years of CR or ad libitum (AL) diet. The average CR in the treatment group through 24 months of follow-up was 12%. Whole blood (baseline, 12, and 24 months) DNAm profiles were measured. Epigenome-wide association study (EWAS) analysis tested CR-induced changes from baseline to 12 and 24 months in the n = 197 participants with available DNAm data. CR treatment was not associated with epigenome-wide significant (false discovery rate [FDR] < 0.05) DNAm changes at the individual-CpG-site level. Secondary analysis of sets of CpG sites identified in published EWAS revealed that CR induced DNAm changes opposite to those associated with higher body mass index and cigarette smoking (p < .003 at 12- and 24-month follow-ups). In contrast, CR altered DNAm at chronological-age-associated CpG sites in the direction of older age (p < .003 at 12- and 24-month follow-ups). Although individual CpG site DNAm changes in response to CR were not identified, analyses of sets CpGs identified in prior EWAS revealed CR-induced changes to blood DNAm. Altered CpG sets were enriched for insulin production, glucose tolerance, inflammation, and DNA-binding and DNA-regulation pathways, several of which are known to be modified by CR. DNAm changes may contribute to CR effects on aging.

Depression can disrupt neural circuits in depression. This industry-supported study used rodents to examine how two antidepressants with grossly different actions affect a neural reward circuit involving the prefrontal cortex (PFC), nucleus accumbens, hippocampus, and amygdala. This circuit is involved in susceptibility, resistance, and antidepressant response to depressogenic circumstances. The test used here was social defeat stress (SDS), a validated animal model of depression. Identically raised inbred mice were determined …

How Mice Cope with Stressful Social Situations

Cross-Reactive DNA Microarray Probes Lead to False Discovery of Autosomal Sex-Associated DNA Methylation