The central melanocortin system as a treatment target for obesity and diabetes: A brief overview

Jinkui Shenqi pills ameliorate diabetes by regulating hypothalamic insulin resistance and POMC/AgRP expression and activity

BACKGROUND

Research on the imbalance of proopiomelanocortin (POMC)/agouti-related protein (AgRP) neurons in the hypothalamus holds potential insights into the pathophysiology of diabetes. Jinkui Shenqi pills (JSP), a prevalent traditional Chinese medicine, regulate hypothalamic function and treat diabetes.

PURPOSE

To investigate the hypoglycemic effect of JSP and explore the probable mechanism in treating diabetes.

METHODS

A type 2 diabetes mouse model was used to investigate the pharmacodynamics of JSP. The glucose-lowering efficacy of JSP was assessed through various metrics including body weight, food consumption, fasting blood glucose (FBG), serum insulin levels, and an oral glucose tolerance test (OGTT). To elucidate the modulatory effects of JSP on hypothalamic mechanisms, we quantified the expression and activity of POMC and AgRP and assessed the insulin-mediated phosphoinositide 3-kinase (PI3K)/protein kinase A (AKT)/forkhead box O1 (FOXO1) pathway in diabetic mice via western blotting and immunohistochemistry. Additionally, primary hypothalamic neurons were exposed to high glucose and palmitic acid levels to induce insulin resistance, and the influence of JSP on POMC/AgRP protein expression and activation was evaluated by PI3K protein inhibition using western blotting and immunofluorescence.

RESULTS

Medium- and high-dose JSP treatment effectively inhibited appetite, resulting in a steady declining trend in body weight, FBG, and OGTT results in diabetic mice (p < 0.05). These JSP groups also had significantly increased insulin levels (p < 0.05). Importantly, the medium-dose group exhibited notable protection of hypothalamic neuronal and synaptic structures, leading to augmentation of dendritic length and branching (p < 0.05). Furthermore, low-, medium-, and high-dose JSP groups exhibited increased phosphorylated (p) INSR, PI3K, pPI3K, AKT, and pAKT expression, as well as decreased FOXO1 and increased pFOXO1 expression, indicating improved hypothalamic insulin resistance in diabetic mice (p < 0.05). Treatment with 10% JSP-enriched serum produced a marked elevation of both expression and activation of POMC (p < 0.05), with a concurrent reduction in AgRP expression and activation within primary hypothalamic neurons (p < 0.05). Intriguingly, these effects could be attributed to the regulatory dynamics of PI3K activity.

CONCLUSION

Our findings suggest that JSP can ameliorate diabetes by regulating POMC/AgRP expression and activity. The insulin-mediated PI3K/AKT/FOXO1 pathway plays an important regulatory role in this intricate process.

Immunohistochemical determination of the excitatory and inhibitory axonal endings contacting NUCB2/nesfatin-1 neurons

Nesfatin-1 is an anorexigenic peptide suppressing food intake and is synthesized and secreted by neurons located in the hypothalamus. Our study was aimed to demonstrate the effect of excitatory and inhibitory neurotransmitters on NUCB2/nesfatin-1 neurons. In this context, dual peroxidase immunohistochemistry staining was performed using NUCB2/nesfatin-1 primary antibody with each of the primary antibodies of vesicular transporter proteins applied as markers for neurons using glutamate, acetylcholine, and GABA as neurotransmitters. In double labeling applied on floating sections, the NUCB2/nesfatin-1 reaction was determined in brown color with diaminobenzidine, while vesicular carrier proteins were marked in black. Slides were analyzed to determine the ratio of nesfatin-1 neurons in the three hypothalamic nucleus in contact with a relevant vesicular carrier protein. The ratios of NUCB2/nesfatin-1 neurons with the innervation were compared among neurotransmitters. In addition, possible gender differences between males and females were examined. The difference in the number of VGLUT2-contacting NUCB2/nesfatin-1 neurons was significantly higher in males when compared to females. When both genders were compared in different nuclei, it was seen that there was no statistical significance in terms of the percentage of NUCB2/nesfatin-1 neuron apposition with VGLUT3. The statistical evaluation showed that number of NUCB2/nesfatin-1 neurons receiving GABAergic innervation is higher in males when compared to females (*p ≤ 0.05; p = 0.045). When the axonal contact of vesicular neurotransmitter transporter proteins was compared between the neurotransmitters, it was determined that the most prominent innervation is GABAergic. In the supraoptic region, no contacts of VAChT-containing axons were found on NUCB2/nesfatin-1 neurons in both female and male subjects. In conclusion, it is understood that both excitatory and inhibitory neurons can innervate the NUCB2/nesfatin-1 neurons and the glutamatergic system is effective in the excitatory innervation while the GABAergic system plays a role in the inhibitory mechanism.

Perinatal metabolic inflammation in the hypothalamus impairs the development of homeostatic feeding circuitry

Over the past few decades, there has been a global increase in childhood obesity. This rise in childhood obesity contributes to the susceptibility of impaired metabolism during both childhood and adulthood. The hypothalamus, specifically the arcuate nucleus (ARC), houses crucial neurons involved in regulating homeostatic feeding. These neurons include proopiomelanocortin (POMC) and agouti-related peptide (AGRP) secreting neurons. They play a vital role in sensing nutrients and metabolic hormones like insulin, leptin, and ghrelin. The neurogenesis of AGRP and POMC neurons completes at birth; however, axon development and synapse formation occur during the postnatal stages in rodents. Insulin, leptin, and ghrelin are the essential regulators of POMC and AGRP neurons. Maternal obesity and postnatal overfeeding or a high-fat diet (HFD) feeding cause metabolic inflammation, disrupted signaling of metabolic hormones, netrin-1, and neurogenic factors, neonatal obesity, and defective neuronal development in animal models; however, the mechanism is unclear. Within the hypothalamus and other brain areas, there exists a wide range of interconnected neuronal populations that regulate various aspects of feeding. However, this review aims to discuss how perinatal metabolic inflammation influences the development of POMC and AGRP neurons within the hypothalamus.

Alpha-melanocyte stimulating hormone (α-MSH): biology, clinical relevance and implication in melanoma

Alpha-melanocyte stimulating hormone (α-MSH) and its receptor, melanocortin 1 receptor (MC1R), have been proposed as potential target for anti-cancer strategies in melanoma research, due to their tissue specific expression and involvement in melanocyte homeostasis. However, their role in prevention and treatment of melanoma is still debated and controversial. Although a large body of evidence supports α-MSH in preventing melanoma development, some preclinical findings suggest that the α-MSH downstream signalling may promote immune escape and cancer resistance to therapy. Additionally, in metastatic melanoma both MC1R and α-MSH have been reported to be overexpressed at levels much higher than normal cells. Furthermore, targeted therapy (e.g. BRAF inhibition in BRAFV600E mutant tumours) has been shown to enhance this phenomenon. Collectively, these data suggest that targeting MC1R could serve as an approach in the treatment of metastatic melanoma. In this review, we explore the molecular biology of α-MSH with particular emphasis into its tumor-related properties, whilst elaborating the experimental evidence currently available regarding the interplay between α-MSH/MC1R axis, melanoma and antitumor strategies.

Mechanisms of sex and gender differences in hypertension

The mechanisms that control blood pressure are multifaceted including the sympathetic nervous system and the renin-angiotensin system leading to vasoconstriction and sodium reabsorption that causes a shift in the pressure-natriuesis relationship to higher blood pressures. Sex steroids can affect these mechanisms either directly or indirectly, and the effects may be different depending on the sex of the individual. This review will discuss some of the major blood pressure-controlling mechanisms and how sex steroids may affect them and the need for future studies to better clarify the mechanisms responsible for sex and gender differences in blood pressure control. New mechanisms that are identified, along with what is already known, will provide better tools for treatment of hypertension in men and women of all ethnicities and decrease the risk of cardiovascular disease in the future.

Association of the rs17782313, rs17773430 and rs34114122 Polymorphisms of/near MC4R Gene with Obesity-Related Biomarkers in a Spanish Pediatric Cohort

Obesity is a multifactorial disease whose onset and development are shaped by the individual genetic background. The melanocortin 4 receptor gene (MC4R) is involved in the regulation of food intake and energy expenditure. Some of the single nucleotide polymorphisms (SNPs) of this gene are related to obesity and metabolic risk factors. The present study was undertaken to assess the relationship between three polymorphism SNPs, namely, rs17782313, rs17773430 and rs34114122, and obesity and metabolic risk factors. One hundred seventy-eight children with obesity aged between 7 and 16 years were studied to determine anthropometric variables and biochemical and inflammatory parameters. Our results highlight that metabolic risk factors, especially alterations in carbohydrate metabolism, were related to rs17782313. The presence of the minor C allele in the three variants (C-C-C) was significantly associated with anthropometric measures indicative of obesity, such as the body mass and fat mass indexes, and increased the values of insulinemia to 21.91 µIU/mL with respect to the wild type values. Our study suggests that the C-C-C haplotype of the SNPs rs17782313, rs17773430 and rs34114122 of the MC4R gene potentiates metabolic risk factors at early ages in children with obesity.

Weight Loss Supplements

Being overweight or obese can predispose people to chronic diseases and metabolic disorders such as cardiovascular illnesses, diabetes, Alzheimer's disease, and cancer, which are costly public health problems and leading causes of mortality worldwide. Many people hope to solve this problem by using food supplements, as they can be self-prescribed, contain molecules of natural origin considered to be incapable of causing damage to health, and the only sacrifice they require is economic. The market offers supplements containing food plant-derived molecules (e.g., primary and secondary metabolites, vitamins, and fibers), microbes (probiotics), and microbial-derived fractions (postbiotics). They can control lipid and carbohydrate metabolism, reduce appetite (interacting with the central nervous system) and adipogenesis, influence intestinal microbiota activity, and increase energy expenditure. Unfortunately, the copious choice of products and different legislation on food supplements worldwide can confuse consumers. This review summarizes the activity and toxicity of dietary supplements for weight control to clarify their potentiality and adverse reactions. A lack of research regarding commercially available supplements has been noted. Supplements containing postbiotic moieties are of particular interest. They are easier to store and transport and are safe even for people with a deficient immune system.

Herbal medicine for the treatment of obesity-associated asthma: a comprehensive review

Obesity is fast growing as a global pandemic and is associated with numerous comorbidities like cardiovascular disease, hypertension, diabetes, gastroesophageal reflux disease, sleep disorders, nephropathy, neuropathy, as well as asthma. Studies stated that obese asthmatic subjects suffer from an increased risk of asthma, and encounter severe symptoms due to a number of pathophysiology. It is very vital to understand the copious relationship between obesity and asthma, however, a clear and pinpoint pathogenesis underlying the association between obesity and asthma is scarce. There is a plethora of obesity-asthma etiologies reported viz., increased circulating pro-inflammatory adipokines like leptin, resistin, and decreased anti-inflammatory adipokines like adiponectin, depletion of ROS controller Nrf2/HO-1 axis, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) associated macrophage polarization, hypertrophy of WAT, activation of Notch signaling pathway, and dysregulated melanocortin pathway reported, however, there is a very limited number of reports that interrelates these pathophysiologies. Due to the underlying complex pathophysiologies exaggerated by obese conditions, obese asthmatics respond poorly to anti-asthmatic drugs. The poor response towards anti-asthmatic drugs may be due to the anti-asthmatics approach only that ignores the anti-obesity target. So, aiming only at the conventional anti-asthmatic targets in obese-asthmatics may prove to be futile until and unless treatment is directed towards ameliorating obesity pathogenesis for a holistic approach towards amelioration of obesity-associated asthma. Herbal medicines for obesity as well as obesity-associated comorbidities are fast becoming safer and more effective alternatives to conventional drugs due to their multitargeted approach with fewer adverse effects. Although, herbal medicines are widely used for obesity-associated comorbidities, however, a limited number of herbal medicines have been scientifically validated and reported against obesity-associated asthma. Notable among them are quercetin, curcumin, geraniol, resveratrol, β-Caryophyllene, celastrol, tomatidine to name a few. In view of this, there is a dire need for a comprehensive review that may summarize the role of bioactive phytoconstituents from different sources like plants, marine as well as essential oils in terms of their therapeutic mechanisms. So, this review aims to critically discuss the therapeutic role of herbal medicine in the form of bioactive phytoconstituents against obesity-associated asthma available in the scientific literature to date.

Decoding Diabetes Biomarkers and Related Molecular Mechanisms by Using Machine Learning, Text Mining, and Gene Expression Analysis

The molecular basis of diabetes mellitus is yet to be fully elucidated. We aimed to identify the most frequently reported and differential expressed genes (DEGs) in diabetes by using bioinformatics approaches. Text mining was used to screen 40,225 article abstracts from diabetes literature. These studies highlighted 5939 diabetes-related genes spread across 22 human chromosomes, with 112 genes mentioned in more than 50 studies. Among these genes, HNF4A, PPARA, VEGFA, TCF7L2, HLA-DRB1, PPARG, NOS3, KCNJ11, PRKAA2, and HNF1A were mentioned in more than 200 articles. These genes are correlated with the regulation of glycogen and polysaccharide, adipogenesis, AGE/RAGE, and macrophage differentiation. Three datasets (44 patients and 57 controls) were subjected to gene expression analysis. The analysis revealed 135 significant DEGs, of which CEACAM6, ENPP4, HDAC5, HPCAL1, PARVG, STYXL1, VPS28, ZBTB33, ZFP37 and CCDC58 were the top 10 DEGs. These genes were enriched in aerobic respiration, T-cell antigen receptor pathway, tricarboxylic acid metabolic process, vitamin D receptor pathway, toll-like receptor signaling, and endoplasmic reticulum (ER) unfolded protein response. The results of text mining and gene expression analyses used as attribute values for machine learning (ML) analysis. The decision tree, extra-tree regressor and random forest algorithms were used in ML analysis to identify unique markers that could be used as diabetes diagnosis tools. These algorithms produced prediction models with accuracy ranges from 0.6364 to 0.88 and overall confidence interval (CI) of 95%. There were 39 biomarkers that could distinguish diabetic and non-diabetic patients, 12 of which were repeated multiple times. The majority of these genes are associated with stress response, signalling regulation, locomotion, cell motility, growth, and muscle adaptation. Machine learning algorithms highlighted the use of the HLA-DQB1 gene as a biomarker for diabetes early detection. Our data mining and gene expression analysis have provided useful information about potential biomarkers in diabetes.

Effects of the POMC System on Glucose Homeostasis and Potential Therapeutic Targets for Obesity and Diabetes

The hypothalamus is indispensable in energy regulation and glucose homeostasis. Previous studies have shown that pro-opiomelanocortin neurons receive both central neuronal signals, such as α-melanocyte-stimulating hormone, β-endorphin, and adrenocorticotropic hormone, as well as sense peripheral signals such as leptin, insulin, adiponectin, glucagon-like peptide-1, and glucagon-like peptide-2, affecting glucose metabolism through their corresponding receptors and related signaling pathways. Abnormalities in these processes can lead to obesity, type 2 diabetes, and other metabolic diseases. However, the mechanisms by which these signal molecules fulfill their role remain unclear. Consequently, in this review, we explored the mechanisms of these hormones and signals on obesity and diabetes to suggest potential therapeutic targets for obesity-related metabolic diseases. Multi-drug combination therapy for obesity and diabetes is becoming a trend and requires further research to help patients to better control their blood glucose and improve their prognosis.