Exercise Rescues Obesogenic-Related Genes in the Female Hypothalamic Arcuate Nucleus: A Potential Role of miR-211 Modulation.

Obesity is a major public health concern that is associated with negative health outcomes. Exercise and dietary restriction are commonly recommended to prevent or combat obesity. This study investigates how voluntary exercise mitigates abnormal gene expression in the hypothalamic arcuate nucleus (ARC) of diet-induced obese (DIO) rats. Using a transcriptomic approach, novel genes in the ARC affected by voluntary wheel running were assessed alongside physiology, pharmacology, and bioinformatics analysis to evaluate the role of miR-211 in reversing obesity. Exercise curbed weight gain and fat mass, and restored ARC gene expression. High-fat diet (HFD) consumption can dysregulate satiety/hunger mechanisms in the ARC. Transcriptional clusters revealed that running altered gene expression patterns, including inflammation and cellular structure genes. To uncover regulatory mechanisms governing gene expression in DIO attenuation, we explored miR-211, which is implicated in systemic inflammation. Exercise ameliorated DIO overexpression of miR-211, demonstrating its pivotal role in regulating inflammation in the ARC. Further, in vivo central administration of miR-211-mimic affected the expression of immunity and cell cycle-related genes. By cross-referencing exercise-affected and miR-211-regulated genes, potential candidates for obesity reduction through exercise were identified. This research suggests that exercise may rescue obesity through gene expression changes mediated partially through miR-211.

Dieting reverses histone methylation and hypothalamic AgRP regulation in obese rats.

Introduction: Although dieting is a key factor in improving physiological functions associated with obesity, the role by which histone methylation modulates satiety/hunger regulation of the hypothalamus through weight loss remains largely elusive. Canonically, H3K9me2 is a transcriptional repressive post-translational epigenetic modification that is involved in obesity, however, its role in the hypothalamic arcuate nucleus (ARC) has not been thoroughly explored. Here we explore the role that KDM4D, a specific demethylase of residue H3K9, plays in energy balance by directly modulating the expression of AgRP, a key neuropeptide that regulates hunger response. Methods: We used a rodent model of diet-induced obesity (DIO) to assess whether histone methylation malprogramming impairs energy balance control and how caloric restriction may reverse this phenotype. Using ChIP-qPCR, we assessed the repressive modification of H3K9me2 at the site of AgRP. To elucidate the functional role of KDM4D in reversing obesity via dieting, a pharmacological agent, JIB-04 was used to inhibit the action of KDM4D in vivo. Results: In DIO, downregulation of Kdm4d mRNA results in both enrichment of H3K9me2 on the AgRP promoter and transcriptional repression of AgRP. Because epigenetic modifications are dynamic, it is possible for some of these modifications to be reversed when external cues are altered. The reversal phenomenon was observed in calorically restricted rats, in which upregulation of Kdm4d mRNA resulted in demethylation of H3K9 on the AgRP promoter and transcriptional increase of AgRP. In order to verify that KDM4D is necessary to reverse obesity by dieting, we demonstrated that in vivo inhibition of KDM4D activity by pharmacological agent JIB-04 in naïve rats resulted in transcriptional repression of AgRP, decreasing orexigenic signaling, thus inhibiting hunger. Discussion: We propose that the action of KDM4D through the demethylation of H3K9 is critical in maintaining a stable epigenetic landscape of the AgRP promoter, and may offer a target to develop new treatments for obesity.

Nitric oxide and l-arginine have mixed effects on mammalian feeding in condition of a high motivation to feed.

Feeding inhibition caused by satiation in rats is partially mediated by the unconventional neurotransmitter nitric oxide (NO). Thus, in satiated rats blocking NO production increases feeding, and treatment with the NO precursor l-arginine or with an NO donor reduces feeding beyond that caused by satiation. Do NO and l-arginine also inhibit feeding when feeding motivation is high? When feeding motivation in satiated animals was hedonically increased by offering a highly attractive food, blocking NO production reduced the quantity eaten, rather than increasing it, indicating that hedonic aspects of food are partially mediated by NO. Increasing NO via an NO donor or l-arginine did not further increase the quantity eaten, indicating a ceiling effect. The NO donor, but not l-arginine, also decreased some motivation-dependent parameters of feeding. When feeding motivation was increased by hunger, quantities of food eaten were unaffected by an NO donor, blocker or precursor, with only the blocker of NO production affecting feeding patterning. We also examined effects on feeding of dissolving l-arginine in drinking water over 3 weeks. Chronic l-arginine administration had different effects during the first and in subsequent weeks, increasing feeding at first, but not later. The data indicate that NO has complex, state dependent effects on both the quantity of food eaten, and on patterns of feeding, probably reflecting different sites and mechanisms of action in the nervous system.

Nitric oxide and l-arginine regulate feeding in satiated rats.

Nitric Oxide (NO) and its precursor l-arginine were found to inhibit feeding in rats with a low motivation to eat, as they do in Aplysia. In rats that are relatively satiated, treatment with an NO blocker increased feeding, and treatment with an NO donor or with either of 2 doses of l-arginine inhibited feeding. NO and l-arginine modulated several parameters of feeding, such as the total duration of appetitive behaviors, the time spent feeding, the quantity of food eaten and the number of feeding bouts. The inhibitory effect of l-arginine on feeding could not be attributed to changes in locomotion. These data indicate that satiation is partially mediated by increased production of NO. NADPH-Diaphorase histochemical staining, which is specific for tissues actively producing NO, showed significantly greater staining in satiated compared to hungry rats in all 4 hypothalamic nuclei (paraventricular and arcuate nuclei, lateral and ventromedial hypothalamus) that were examined. l-arginine may act as a regulator of feeding by controlling NO production in several hypothalamic nuclei, specifically under condition of a low feeding motivation.

Effects of cannabidiol in males and females in two different rat models of depression.

The current study explores the therapeutic potential of Cannabidiol (CBD), a compound in the Cannabis plant, using both sexes of 2 "depressive-like" genetic models, Wistar Kyoto (WKY) and Flinders Sensitive Line (FSL) rats. Rats ingested CBD (30 mg/kg) orally. In the saccharin preference test, following a previous report of a pro-hedonic effect of CBD in male WKY, we now found similar results in female WKY. CBD also decreased immobility in the forced swim test in males (both strains) and in female WKY. These findings suggest a role for CBD in treating mental disorders with prominent symptoms of helplessness and anhedonia.