The role of context in repeated confrontations between male rats using the resident-intruder paradigm

Vinyl chloride (VC) is a confirmed human carcinogen associated with hepatocellular carcinoma and angiosarcoma. However, the role of microRNAs (miRNAs) in liver cell cycle changes under VC exposure remains unclear, which prevents research on the mechanism of VC-induced carcinogenesis. In this study, male rats were injected intraperitoneally with VC (0, 5, 25, and 125 mg/kg body weight) for 6, 8, and 12 weeks. Cell cycle analysis of liver cells, miRNA-222, miRNA-199a, miRNA-195, and miRNA-125b expression in the liver and serum, and target protein expression were performed at different time points. The results showed a higher percentage of hepatocytes in the G1/G0 and S phases at the end of 6 and 12 weeks of VC exposure, respectively. MiRNA-222 expression decreased initially and then increased, whereas miRNA-199a, miRNA-195, and miRNA-125b expression increased initially and then decreased, which corresponded with changes in cell cycle distribution and related target proteins expression (p27, cyclinA, cyclinD1, and CDK6). The corresponding expression levels of miRNAs in serum did not change. Dynamic changes in miR-222, miR-199a, miR-195, and miR-125b induced by VC can lead to cell cycle deregulation by affecting cell cycle-related proteins, and these miRNAs can serve as early biomarkers for malignant transformation caused by VC.

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Role of nucleus accumbens microRNA-181a and MeCP2 in incubation of heroin craving in male rats

Psychopharmacology ◽

10.1007/s00213-021-05854-3 ◽

2021 ◽

Author(s):

Wenjin Xu ◽

Qingxiao Hong ◽

Zi Lin ◽

Hong Ma ◽

Weisheng Chen ◽

...

Keyword(s):

Nucleus Accumbens ◽

Male Rats

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DNA Methyltransferase 3A Is Involved in the Sustained Effects of Chronic Stress on Synaptic Functions and Behaviors

Cerebral Cortex ◽

10.1093/cercor/bhaa337 ◽

2020 ◽

Author(s):

Jing Wei ◽

Jia Cheng ◽

Nicholas J Waddell ◽

Zi-Jun Wang ◽

Xiaodong Pang ◽

...

Keyword(s):

Dna Methylation ◽

Dna Methyltransferase ◽

Epigenetic Modification ◽

Substantial Reduction ◽

Dna Methyltransferases ◽

Male Rats ◽

Neural Pathways ◽

Dnmt Inhibitors ◽

Synaptic Functions

Abstract Emerging evidence suggests that epigenetic mechanisms regulate aberrant gene transcription in stress-associated mental disorders. However, it remains to be elucidated about the role of DNA methylation and its catalyzing enzymes, DNA methyltransferases (DNMTs), in this process. Here, we found that male rats exposed to chronic (2-week) unpredictable stress exhibited a substantial reduction of Dnmt3a after stress cessation in the prefrontal cortex (PFC), a key target region of stress. Treatment of unstressed control rats with DNMT inhibitors recapitulated the effect of chronic unpredictable stress on decreased AMPAR expression and function in PFC. In contrast, overexpression of Dnmt3a in PFC of stressed animals prevented the loss of glutamatergic responses. Moreover, the stress-induced behavioral abnormalities, including the impaired recognition memory, heightened aggression, and hyperlocomotion, were partially attenuated by Dnmt3a expression in PFC of stressed animals. Finally, we found that there were genome-wide DNA methylation changes and transcriptome alterations in PFC of stressed rats, both of which were enriched at several neural pathways, including glutamatergic synapse and microtubule-associated protein kinase signaling. These results have therefore recognized the potential role of DNA epigenetic modification in stress-induced disturbance of synaptic functions and cognitive and emotional processes.

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Stress Modifies the Expression of Glucocorticoid-Responsive Genes by Acting at Epigenetic Levels in the Rat Prefrontal Cortex: Modulatory Activity of Lurasidone

International Journal of Molecular Sciences ◽

10.3390/ijms22126197 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6197

Author(s):

Paola Brivio ◽

Giulia Sbrini ◽

Letizia Tarantini ◽

Chiara Parravicini ◽

Piotr Gruca ◽

...

Keyword(s):

Gene Expression ◽

Dna Methylation ◽

Chronic Stress ◽

Chronic Mild Stress ◽

Male Rats ◽

Mild Stress ◽

Experimental Conditions ◽

Glucocorticoid Responsive Element ◽

Responsive Element

Epigenetics is one of the mechanisms by which environmental factors can alter brain function and may contribute to central nervous system disorders. Alterations of DNA methylation and miRNA expression can induce long-lasting changes in neurobiological processes. Hence, we investigated the effect of chronic stress, by employing the chronic mild stress (CMS) and the chronic restraint stress protocol, in adult male rats, on the glucocorticoid receptor (GR) function. We focused on DNA methylation specifically in the proximity of the glucocorticoid responsive element (GRE) of the GR responsive genes Gadd45β, Sgk1, and Gilz and on selected miRNA targeting these genes. Moreover, we assessed the role of the antipsychotic lurasidone in modulating these alterations. Chronic stress downregulated Gadd45β and Gilz gene expression and lurasidone normalized the Gadd45β modification. At the epigenetic level, CMS induced hypermethylation of the GRE of Gadd45β gene, an effect prevented by lurasidone treatment. These stress-induced alterations were still present even after a period of rest from stress, indicating the enduring nature of such changes. However, the contribution of miRNA to the alterations in gene expression was moderate in our experimental conditions. Our results demonstrated that chronic stress mainly affects Gadd45β expression and methylation, effects that are prolonged over time, suggesting that stress leads to changes in DNA methylation that last also after the cessation of stress procedure, and that lurasidone is a modifier of such mechanisms.

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Role of Melanocortin Signaling in Neuroendocrine and Metabolic Actions of Leptin in Male Rats With Uncontrolled Diabetes

Endocrinology ◽

10.1210/en.2014-1169 ◽

2014 ◽

Vol 155 (11) ◽

pp. 4157-4167 ◽

Cited By ~ 16

Author(s):

Thomas H. Meek ◽

Miles E. Matsen ◽

Vincent Damian ◽

Alex Cubelo ◽

Streamson C. Chua ◽

...

Keyword(s):

Male Rats ◽

Melanocortin Receptor ◽

Glucose Lowering ◽

Glucose Levels ◽

Blood Glucose Levels ◽

Uncontrolled Diabetes ◽

Streptozotocin Induced Diabetes ◽

Melanocortin Signaling ◽

Antidiabetic Effects

Abstract Although the antidiabetic effects of leptin require intact neuronal melanocortin signaling in rodents with uncontrolled diabetes (uDM), increased melanocortin signaling is not sufficient to mimic leptin's glucose-lowering effects. The current studies were undertaken to clarify the role of melanocortin signaling in leptin's ability to correct metabolic and neuroendocrine disturbances associated with uDM. To accomplish this, bilateral cannulae were implanted in the lateral ventricle of rats with streptozotocin-induced diabetes, and leptin was coinfused with varying doses of the melanocortin 3/4 receptor (MC3/4R) antagonist, SHU9119. An additional cohort of streptozotocin-induced diabetes rats received intracerebroventricular administration of either the MC3/4R agonist, melanotan-II, or its vehicle. Consistent with previous findings, leptin's glucose-lowering effects were blocked by intracerebroventricular SHU9119. In contrast, leptin-mediated suppression of hyperglucagonemia involves both melanocortin dependent and independent mechanisms, and the degree of glucagon inhibition was associated with reduced plasma ketone body levels. Increased central nervous system melanocortin signaling alone fails to mimic leptin's ability to correct any of the metabolic or neuroendocrine disturbances associated with uDM. Moreover, the inability of increased melanocortin signaling to lower diabetic hyperglycemia does not appear to be secondary to release of the endogenous MC3/4R inverse agonist, Agouti-related peptide (AgRP), because AgRP knockout mice did not show increased susceptibility to the antidiabetic effects of increased MC3/4R signaling. Overall, these data suggest that 1) AgRP is not a major driver of diabetic hyperglycemia, 2) mechanisms independent of melanocortin signaling contribute to leptin's antidiabetic effects, and 3) melanocortin receptor blockade dissociates leptin's glucose-lowering effect from its action on other features of uDM, including reversal of hyperglucagonemia and ketosis, suggesting that brain control of ketosis, but not blood glucose levels, is glucagon dependent.

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