Leptin: structure, function and biology

Transcriptomics and non-targeted metabolomics provide mechanistic insights into the improvement of the growth performance and meat quality of lambs supplemented with fermented Lycium barbarum residues

This study investigated the effects of Lycium barbarum residues (LBR) and fermented L. barbarum residues (FLBR) on the growth performance and meat quality of lambs. Eighteen lambs were randomly assigned into three groups and fed either a basal diet (CON) or the same diet supplemented with 5.0% LBR or FLBR for a period of 90 days. The underlying mechanisms responsible for the beneficial effect of LBR and FLBR on the longissimus thoracis (LT) and intramuscular fat (IMF) tissues of lambs were examined using multiomics techniques. Our findings showed that FLBR supplementation significantly enhanced the average daily gain, feed efficiency, and nutrient digestibility (P < 0.05 or P < 0.01). Serum total protein (P = 0.007) and glucose (P = 0.002) levels were higher in the FLBR-fed lambs, while urea nitrogen level was lower (P = 0.001). Additionally, the levels of rumen acetate (P = 0.002) and propionate (P = 0.011) were significantly elevated, while ammonia-nitrogen (NH3-N), isobutyrate and isovalerate decreased (P < 0.05 or P < 0.01) following FLBR supplementation. Post-mortem meat quality was also improved by FLBR, as evidenced by enhanced total antioxidant capacity, superoxide dismutase activity, pH, redness (a∗), tenderness and water holding capacity (P < 0.05 or P < 0.01), alongside a reduction in the malonaldehyde content (P < 0.001). Transcriptomic analysis identified 962 differentially expressed genes (DEGs, FLBR vs CON) and 782 DEGs (FLBR vs LBR) in LT, and 1313 DEGs (FLBR vs CON) and 1221 DEGs (FLBR vs LBR) in IMF. The ribosome signaling pathway related genes in LT tissue were activated by the FLBR diet (P < 0.05), showing a higher anabolism of protein. The genes involved in fatty acid biosynthesis in IMF tissue were upregulated by the FLBR diet (P < 0.05), showing a higher anabolism of lipids. Metabolomics analysis identified the 1732 differential metabolites in LT tissue following FLBR supplementation, with significant alterations in metabolites such as carnosine, L-arginine and L-proline, which may serve as potential biomarkers for meat quality betterment. In conclusion, FLBR supplementation might have modified anabolism of proteins and fatty acid, as well as muscle metabolomic profiles, leading to improvements in both growth performance and meat quality in fattening lambs.

Gut Microbiota-Bone Axis

BACKGROUND

Knowledge of the complex interplay between gut microbiota and human health is gradually increasing as it has just recently been a field of such great interest.

SUMMARY

Recent studies have reported that communities of microorganisms inhabiting the gut influence the immune system through cellular responses and shape many physiological and pathophysiological aspects of the body, including muscle and bone metabolism (formation and resorption). Specifically, the gut microbiota affects skeletal homeostasis through changes in host metabolism, the immune system, hormone secretion, and the gut-brain axis. The major role on gut-bone axis is due to short-chain fatty acids (SCFAs). They have the ability to influence regulatory T-cell (Tregs) development and activate bone metabolism through the action of Wnt10. SCFA production may be a mechanism by which the microbial community, by increasing the serum level of insulin-like growth factor 1 (IGF-1), leads to the growth and regulation of bone homeostasis. A specific SCFA, butyrate, diffuses into the bone marrow where it expands Tregs. The Tregs induce production of the Wnt ligand Wnt10b by CD8+ T cells, leading to activation of Wnt signaling and stimulation of bone formation. At the hormonal level, the effect of the gut microbiota on bone homeostasis is expressed through the biphasic action of serotonin. Some microbiota, such as spore-forming microbes, regulate the level of serotonin in the gut, serum, and feces. Another group of bacterial species (Lactococcus, Mucispirillum, Lactobacillus, and Bifidobacterium) can increase the level of peripheral/vascular leptin, which in turn manages bone homeostasis through the action of brain serotonin.

Dysregulation of Metabolic Peptides Precedes Hyperinsulinemia and Inflammation Following Exposure to Rotenone in Rats

Rotenone, a naturally occurring compound derived from the roots of tropical plants, is used as a broad-spectrum insecticide, piscicide, and pesticide. It is a classical, high-affinity mitochondrial complex I inhibitor that causes not only oxidative stress, α-synuclein phosphorylation, DJ-1 (Parkinson's disease protein 7) modifications, and inhibition of the ubiquitin-proteasome system but it is also widely considered an environmental contributor to Parkinson's disease (PD). While prodromal symptoms, such as loss of smell, constipation, sleep disorder, anxiety/depression, and the loss of dopaminergic neurons in the substantia nigra of rotenone-treated animals, have been reported, alterations of metabolic hormones and hyperinsulinemia remain largely unknown and need to be investigated. Whether rotenone and its effect on metabolic peptides could be utilized as a biomarker for its toxic metabolic effects, which can cause long-term detrimental effects and ultimately lead to obesity, hyperinsulinemia, inflammation, and possibly gut-brain axis dysfunction, remains unclear. Here, we show that rotenone disrupts metabolic homeostasis, altering hormonal peptides and promoting infiltration of inflammatory T cells. Specifically, our results indicate a significant decrease in glucagon-like peptide-1 (GLP-1), C-peptide, and amylin. Interestingly, levels of several hormonal peptides related to hyperinsulinemia, such as insulin, leptin, pancreatic peptide (PP), peptide YY (PYY), and gastric inhibitory polypeptide (GIP), were significantly upregulated. Administration of rotenone to rats also increased body weight and activated macrophages and inflammatory T cells. These data strongly suggest that rotenone disrupts metabolic homeostasis, leading to obesity and hyperinsulinemia. The potential implications of these findings are vast, given that monitoring these markers in the blood could not only provide a crucial tool for assessing the extent of exposure and its relevance to obesity and inflammation but could also open new avenues for future research and potential therapeutic strategies.

Porcine transient receptor potential channel 1 promotes adipogenesis and lipid deposition

Adipose tissue, an important organ involved in energy metabolism and endocrine, is closely related to animal meat quality and human health. Transient receptor potential channel 1 (TRPC1), an ion transporter, is adipocytes' major Ca2+ entry channel. However, its function in fat deposition is poorly understood, particularly in pigs, which are both an ideal model for human obesity research and a primary meat source for human diets. In the present investigation, our findings demonstrate a prominent expression of TRPC1 within the adipose tissue of pigs with a strong fat deposition ability. Functional analysis showed that TRPC1 promotes primary preadipocyte proliferation and adipogenic differentiation. In vivo, transgenic mice expressing porcine TRPC1 exhibited aggravated high-fat diet-induced obesity, hepatic steatosis, and insulin resistance. Moreover, TRPC1 may facilitate adipogenesis via activating phosphatidylinositol 3 kinase/AKT and β-catenin signaling pathways. Our research underscores the pivotal role of porcine TRPC1 as a positive regulator in adipogenesis and lipid accumulation processes, providing a potential target for improving animal meat quality and treating obesity-related diseases in humans.

[The role of leptin in endometrium disorders: literature review]

Leptin is not only the main regulator of energy balance, but also it affects the reproductive and immune systems. Leptin and its receptors are expressed in the endometrium and are actively involved in the embryo implantation. According to numerous studies, expression and level changes of leptin are associated with the inflammatory and autoimmune diseases, including endometriosis and chronic endometritis. Hyperplastic and inflammatory diseases of the uterus are accompanied by a violation of the receptivity of the endometrium due to the dysregulation of many factors involved in proliferation, vascularization and decidualization of cells. Activity of most of these factors is due to the leptin action, however, there are no studies of the direct effect of leptin in the pathogenesis of disorders of the endometrium in hyperplastic and inflammatory diseases.Thus, the purpose of this literature review was to describe the putative molecular mechanisms of the effect of leptin on the development of endometrial pathology.Literature search was carried out from 03/20/2023 to 05/11/2023 using scientific literature databases: NCBI PubMed, Google Scholar (foreign sources), Cyberleninka, Elibrary (domestic sources): references for the period 1995-2023 were analyzed. The following keywords were used for the search: leptin, endometrial dysfunction, endometrial receptivity, inflammation, pelvic inflammatory disease.

Novel perspectives on leptin in osteoarthritis: Focus on aging

Osteoarthritis (OA) is a common chronic joint disease characterized by articular cartilage degeneration, subchondral sclerosis, synovitis, and osteophyte formation. OA is associated with disability and impaired quality of life, particularly among the elderly. Leptin, a 16-kD non-glycosylated protein encoded by the obese gene, is produced on a systemic and local basis in adipose tissue and the infrapatellar fat pad located in the knee. The metabolic mechanisms employed by leptin in OA development have been widely studied, with attention being paid to aging as a corroborative risk factor for OA. Hence, in this review, we have attempted to establish a potential link between leptin and OA, by focusing on aging-associated mechanisms and proposing leptin as a potential diagnostic and therapeutic target in aging-related mechanisms of OA that may provide fruitful guidance and emphasis for future research.

A peptide derived from the amino terminus of leptin improves glucose metabolism and energy homeostasis in myotubes and db/db mice

Leptin is an adipokine, which plays key roles in regulation of glucose metabolism and energy homeostasis. Therefore, identification of a short peptide from leptin which improves glucose-metabolism and energy-homeostasis could be of significant therapeutic importance. Mutational studies demonstrated that N-terminal of human leptin hormone is crucial for activation of leptin-receptor while its C-terminal seems to have lesser effects in it. Thus, for finding a metabolically active peptide and complimenting the mutational studies on leptin, we have identified a 17-mer (leptin-1) and a 16-mer (leptin-2) segment from its N-terminal and C-terminal, respectively. Consistent with the mutational studies, leptin-1 improved glucose-metabolism by increasing glucose-uptake, GLUT4 expression and its translocation to the plasma membrane in L6-myotubes, while leptin-2 was mostly inactive. Leptin-1-induced glucose-uptake is mediated through activation of AMPK, PI3K, and AKT proteins since inhibitors of these proteins inhibited the event. Leptin-1 activated leptin-receptor immediate downstream target protein, JAK2 reflecting its possible interaction with leptin-receptor while leptin-2 was less active. Furthermore, leptin-1 increased mitochondrial-biogenesis and ATP-production, and increased expression of PGC1α, NRF1, and Tfam proteins, that are important regulators of mitochondrial biogenesis. The results suggested that leptin-1 improved energy-homeostasis in L6-myotubes, whereas, leptin-2 showed much lesser effects. In diabetic, db/db mice, leptin-1 significantly decreased blood glucose level and improved glucose-tolerance. Leptin-1 also increased serum adiponectin and decreased serum TNF-α and IL-6 level signifying the improvement in insulin-sensitivity and decrease in insulin-resistance, respectively in db/db mice. Overall, the results show the identification of a short peptide from the N-terminal of human leptin hormone which significantly improves glucose-metabolism and energy-homeostasis.

Nutrition, Growth, and Age at Puberty in Heifers

Puberty onset and age at first calving have a critical impact on livestock production for good reproductive efficiency of the herd and to reduce the duration of the non-productive stage of the growing heifer. Besides genetic factors, sexual maturation is also affected by environmental factors, such as nutrition, which can account for up to 20% of the observed variability. The rate of body weight gain during growth is considered the main variable influencing the age at puberty, dependent on planes of nutrition in growing animals during the prepubertal-to-pregnancy stage. This paper reviews current knowledge concerning nutrition management and attainment of puberty in heifers, considering the relevance of some indicators such as body measurements and hormones strictly linked to the growth and puberty process. Puberty onset is dependent on the acquisition of adequate subcutaneous adipose tissue mass, as it is the main source of the hormone leptin. Until a certain level, body condition score and age at puberty are negatively correlated, but beyond that, for fatter animals, such correlation is gradually lost. Age at puberty in heifers was reported to be negatively related to IGF-1. Future research should be planned considering the need to standardize the experimental animals and conditions.

Puberty in beef heifers: effects of prenatal and postnatal nutrition on the development of the neuroendocrine axis

Reproductive maturation is a complex physiological process controlled by the neuroendocrine system and is characterized by an increase in gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) pulsatile secretion. Nutrition during early development is a key factor regulating puberty onset, which is defined as first ovulation in females. In heifers, nutrient restriction after weaning delays puberty, whereas elevated levels of nutrition and energy reserves advance reproductive maturation. Recent studies in cattle and other animal models have shown that the dam's nutrition during gestation can also program the neuroendocrine system in the developing fetus and has the potential to alter timing of puberty in the offspring. Among the metabolic signals that modulate brain development and control timing of puberty is leptin, a hormone produced primarily by adipocytes that communicates energy status to the brain. Leptin acts within the arcuate nucleus of the hypothalamus to regulate GnRH secretion via an upstream network of neurons that includes neurons that express neuropeptide Y (NPY), an orexigenic peptide with inhibitory effects on GnRH secretion, and alpha melanocyte-stimulating hormone (αMSH), an anorexigenic peptide with excitatory effects on GnRH neurons. Another important population of neurons are KNDy neurons, neurons in the arcuate nucleus that co-express the neuropeptides kisspeptin, neurokinin B, and dynorphin and have strong stimulatory effects on GnRH secretion. Our studies in beef heifers indicate that increased nutrition between 4 to 8 months of age advances puberty by diminishing NPY inhibitory tone and by increasing excitatory inputs of αMSH and kisspeptin, which collectively lead to increased GnRH/LH pulsatility. Our ongoing studies indicate that different planes of nutrition during gestation can alter maternal leptin concentrations and promote changes in the fetal brain. Nonetheless, at least in Bos indicus-influenced heifers, deficits programmed prenatally can be overcome by adequate postnatal nutrition without negatively impacting age at puberty or subsequent fertility.

Examining the Potential Applicability of Orexigenic and Anorexigenic Peptides in Veterinary Medicine for the Management of Obesity in Companion Animals

This review article comprehensively explores the role of orexigenic and anorexigenic peptides in the management of obesity in companion animals, with a focus on clinical applications. Obesity in domestic animals, particularly dogs and cats, is prevalent, with significant implications for their health and well-being. Factors contributing to obesity include overfeeding, poor-quality diet, lack of physical activity, and genetic predispositions. Despite the seriousness of this condition, it is often underestimated, with societal perceptions sometimes reinforcing unhealthy behaviors. Understanding the regulation of food intake and identifying factors affecting the function of food intake-related proteins are crucial in combating obesity. Dysregulations in these proteins, whether due to genetic mutations, enzymatic dysfunctions, or receptor abnormalities, can have profound health consequences. Molecular biology techniques play a pivotal role in elucidating these mechanisms, offering insights into potential therapeutic interventions. The review categorizes food intake-related proteins into anorexigenic peptides (inhibitors of food intake) and orexigenic peptides (enhancers of food intake). It thoroughly examines current research on regulating energy balance in companion animals, emphasizing the clinical application of various peptides, including ghrelin, phoenixin (PNX), asprosin, glucagon-like peptide 1 (GLP-1), leptin, and nesfatin-1, in veterinary obesity management. This comprehensive review aims to provide valuable insights into the complex interplay between peptides, energy balance regulation, and obesity in companion animals. It underscores the importance of targeted interventions and highlights the potential of peptide-based therapies in improving the health outcomes of obese pets.

Altered leptin level in autism spectrum disorder and meta-analysis of adipokines

BACKGROUND

Increasing evidence suggests that leptin is involved in the pathology of autism spectrum disorder (ASD). In this study, our objective was to investigate the levels of leptin in the blood of children with ASD and to examine the overall profile of adipokine markers in ASD through meta-analysis.

METHODS

Leptin concentrations were measured using an enzyme-linked immunosorbent assay (ELISA) kit, while adipokine profiling, including leptin, was performed via meta-analysis. Original reports that included measurements of peripheral adipokines in ASD patients and healthy controls (HCs) were collected from databases such as Web of Science, PubMed, and Cochrane Library. These studies were collected from September 2022 to September 2023 and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Standardized mean differences were calculated using a random effects model for the meta-analysis. Additionally, we performed meta-regression and explored heterogeneity among studies.

RESULTS

Our findings revealed a significant increase in leptin levels in children with ASD compared to HCs (p = 0.0319). This result was consistent with the findings obtained from the meta-analysis (p < 0.001). Furthermore, progranulin concentrations were significantly reduced in children with ASD. However, for the other five adipokines analyzed, there were no significant differences observed between the children with ASD and HCs children. Heterogeneity was found among the studies, and the meta-regression analysis indicated that publication year and latitude might influence the results of the meta-analysis.

CONCLUSIONS

These findings provide compelling evidence that leptin levels are increased in children with ASD compared to healthy controls, suggesting a potential mechanism involving adipokines, particularly leptin, in the pathogenesis of ASD. These results contribute to a better understanding of the pathology of ASD and provide new insights for future investigations.

Advances in uremic toxin detection and monitoring in the management of chronic kidney disease progression to end-stage renal disease

Patients with end-stage kidney disease (ESKD) rely on dialysis to remove toxins and stay alive. However, hemodialysis alone is insufficient to completely remove all/major uremic toxins, resulting in the accumulation of specific toxins over time. The complexity of uremic toxins and their varying clearance rates across different dialysis modalities poses significant challenges, and innovative approaches such as microfluidics, biomarker discovery, and point-of-care testing are being investigated. This review explores recent advances in the qualitative and quantitative analysis of uremic toxins and highlights the use of innovative methods, particularly label-mediated and label-free surface-enhanced Raman spectroscopy, primarily for qualitative detection. The ability to analyze uremic toxins can optimize hemodialysis settings for more efficient toxin removal. Integration of multiple omics disciplines will also help identify biomarkers and understand the pathogenesis of ESKD, provide deeper understanding of uremic toxin profiling, and offer insights for improving hemodialysis programs. This review also highlights the importance of early detection and improved understanding of chronic kidney disease to improve patient outcomes.

AMP-activated protein kinase activation suppresses leptin expression independently of adipogenesis in primary murine adipocytes

Adipogenesis, defined as the development of mature adipocytes from stem cell precursors, is vital for the expansion, turnover and health of adipose tissue. Loss of adipogenic potential in adipose stem cells, or impairment of adipogenesis is now recognised as an underlying cause of adipose tissue dysfunction and is associated with metabolic disease. In this study, we sought to determine the role of AMP-activated protein kinase (AMPK), an evolutionarily conserved master regulator of energy homeostasis, in adipogenesis. Primary murine adipose-derived stem cells were treated with a small molecule AMPK activator (BI-9774) during key phases of adipogenesis, to determine the effect of AMPK activation on adipocyte commitment, maturation and function. To determine the contribution of the repression of lipogenesis by AMPK in these processes, we compared the effect of pharmacological inhibition of acetyl-CoA carboxylase (ACC). We show that AMPK activation inhibits adipogenesis in a time- and concentration-dependent manner. Transient AMPK activation during adipogenic commitment leads to a significant, ACC-independent, repression of adipogenic transcription factor expression. Furthermore, we identify a striking, previously unexplored inhibition of leptin gene expression in response to both short-term and chronic AMPK activation irrespective of adipogenesis. These findings reveal that in addition to its effect on adipogenesis, AMPK activation switches off leptin gene expression in primary mouse adipocytes independently of adipogenesis. Our results identify leptin expression as a novel target of AMPK through mechanisms yet to be identified.

Methylation of the leptin gene promoter is associated with a negative correlation between leptin concentration and body fat in Tupaia belangeri

AIMS

Leptin is a signaling protein secreted by white adipose tissue encoded by the obesity gene, and its main function is to regulate the food intake and energy metabolism in mammals. Previous studies had found that animal leptin concentration was positively correlated with its body fat, but the leptin concentration of Tupaia belangeri was negatively correlated with its body fat mass. The present study attempted to investigate the mechanisms of leptin concentration negatively correlated with its body fat mass in T. belangeri.

MATERIAL AND METHODS

We measured the leptin concentration of the two groups of animals by enzyme linked immunosorbent assay (ELISA) and quantified the leptin mRNA expression by qPCR. Then, the histological, transcriptomic, and bisulfite sequencing of the two groups of animals were studied. Moreover, to investigate the energy metabolism under the negative correlation, we also analyzed the metabolomics and metabolic rate in T. belangeri.

KEY FINDINGS

We revealed the negative correlation was mediated by leptin gene methylation of subcutaneous adipose tissue. Further, we also found that T. belangeri increased energy metabolism with leptin decreased.

SIGNIFICANCE

We challenge the traditional view that leptin concentration was positively correlated with body fat mass, and further revealed its molecular mechanism and energy metabolism strategy. This special leptin secretion mechanism and energy metabolism strategy enriched our understanding of energy metabolism of animals, which provided an opportunity for the clinical transformation of metabolic diseases.

Sleep and cardiometabolic risk. Narrative revision

OBJECTIVES

Sleep disturbances, including disrupted sleep and short sleep duration, are highly prevalent and are prospectively associated with an increased risk for various chronic diseases, including cardiometabolic, neurodegenerative, and autoimmune diseases.

MATERIAL AND METHODS

This is a narrative review of the literature based on numerous articles published in peer-reviewed journals since the beginning of this century.

RESULTS

The relationship between sleep disorders and metabolic dysregulation has been clearly established, mainly in the setting of modern epidemic of cardiometabolic disease, a cluster of conditions include obesity, insulin resistance, arterial hypertension, and dyslipidaemia, all of them considered as main risk factor for atherosclerotic cardiovascular disease (ACVD) and its clinical expression such as ischemic ictus, myocardial infarction and type 2 diabetes. Clinically viable tools to measure sleep duration and quality are needed for routine screening and intervention.

CONCLUSIONS

In view of what has been exposed in this review, it is evident that the timing, amount, and quality of sleep are critical to reduce the burden of risk factors for several chronic disease, including ACVD and type 2 diabetes, and most relevant in young people. Future research studies should elucidate the effectiveness of multimodal interventions to counteract the risk of short sleep for optimal patient outcomes across the healthcare continuum, especially in young people.

Expression of Genes Encoding Selected Orexigenic and Anorexigenic Peptides and Their Receptors in the Organs of the Gastrointestinal Tract of Calves and Adult Domestic Cattle (Bos taurus taurus)

The regulation of food intake occurs at multiple levels, and two of the components of this process are orexigenic and anorexigenic peptides, which stimulate or inhibit appetite, respectively. The study of the function of these compounds in domestic cattle is essential for production efficiency, animal welfare, and health, as well as for economic benefits, environmental protection, and the contribution to a better understanding of physiological aspects that can be applied to other species. In this study, the real-time PCR method was utilized to determine the expression levels of GHRL, GHSR, SMIM20, GPR173, LEP, LEPR, and NUCB2 (which encode ghrelin, its receptor, phoenixin-14, its receptor, leptin, its receptor, and nesfatin-1, respectively) in the gastrointestinal tract (GIT) of Polish Holstein-Friesian breed cattle. In all analyzed GIT segments, mRNA for all the genes was present in both age groups, confirming their significance in these tissues. Gene expression levels varied distinctly across different GIT segments and between young and mature subjects. The differences between calves and adults were particularly pronounced in areas such as the forestomachs, ileum, and jejunum, indicating potential changes in peptides regulating food intake based on the developmental phase. In mature individuals, the forestomachs predominantly displayed an increase in GHRL expression, while the intestines had elevated levels of GHSR, GPR173, LEP, and NUCB2. In contrast, the forestomachs in calves showed upregulated expressions of LEP, LEPR, and NUCB2, highlighting the potential importance of peptides from these genes in bovine forestomach development.

Carbon Dioxide (CO2) Dietary Emissions Are Related to Oxidative and Inflammatory Status in Adult Population

BACKGROUND

Carbon dioxide (CO2) is a primary greenhouse gas (GHG) causing global temperature to rise. Unsustainable diets induce an increment in the risk of obesity and noncommunicable diseases but also contribute to the global GSG burden.

OBJECTIVE

To assess whether CO2 dietary emissions influence the inflammatory and oxidative status of subjects with metabolic syndrome (MetS).

METHODS

As part of the PREDIMED-Plus study, 100 adults (55-75 years old) from the Balearic Islands, Spain, were recruited and classified according to their dietary CO2 emissions. Anthropometric parameters were determined, fasting blood samples were collected and plasma, neutrophils, and peripheral blood mononuclear cells (PBMCs) were obtained. Dietary inflammatory index (DII), adherence to a Mediterranean diet (ADM), fatty liver index (FLI), and estimated glomerular filtration (eGFR) were calculated. Clinical biochemical parameters, blood count, and oxidative stress and inflammatory biomarker levels were also determined.

RESULTS

DII was higher in participants with high dietary CO2 emissions. Adherence to the MedDiet was inversely associated with CO2 emissions. Malondialdehyde (MDA) levels were higher in urine and plasma samples from subjects with high dietary CO2 emissions. Reactive oxygen species (ROS) production by PBMCs was greater in participants with high CO2 emissions. Interleukin-15, resistin, and leptin plasma levels were increased in participants with high dietary CO2 emissions.

CONCLUSION

Dietary CO2 emissions influence oxidative status and inflammation in relation to the increased prooxidative and proinflammatory status in PBMCs and plasma. These biomarkers were useful for monitoring diet sustainability and health.

Leptin and male fertility: unraveling the molecular pathways, receptor functions, and therapeutic potential

Leptin, an adipokine hormone, is a critical regulator of energy homeostasis, appetite, and metabolism. Recent advances have elucidated its role in male fertility. This forum provides an overview of the interplay between leptin, its receptors, and signaling pathways in the context of male fertility, revealing its multifaceted impact on reproductive health.

Genetic Association of LEP Gene Polymorphisms with Obesity in Moroccan Individuals: Case-Control Study and Updated Meta-analysis

Obesity is a global epidemic disease representing the fifth leading cause of death in the world. It was shown that it is caused by the interaction between environmental factors and genes including leptin gene (LEP). This paper aimed to analyze the association between the LEP gene polymorphisms rs7799039 and rs11761556 with obesity in Moroccan individuals as well as to perform an update meta-analysis of this genetic association. Both polymorphisms were genotyped in 146 obesity patients and 104 controls using real-time PCR technique. The genetic association analysis and the comparison of quantitative parameters were carried out using the R language. Moreover, a meta-analysis including 20 genetic association studies was performed using Review Manager 5.3 software. No significant association was found between the polymorphisms rs7799039 and rs11761556 and the risk of obesity. The comparison of biochemical and clinical parameters between the genotypes of the rs7799039 polymorphism, showed a significant increased triglycerides levels in carriers of AA or GA genotypes (P value = 0.040). The meta-analysis showed no significant association between the rs7799039 polymorphism and obesity under all genetic models. In conclusion, the case-control study and meta-analysis demonstrated that the LEP gene polymorphisms rs7799039 and rs11761556 cannot be considered as genetic risk factors for obesity.

Targeting Renal Proximal Tubule Cells in Obesity-Related Glomerulopathy

As a metabolic disorder, obesity can cause secondary kidney damage, which is called obesity-related glomerulopathy (ORG). As the incidence of obesity increases worldwide, so does the incidence of end-stage renal disease (ESRD) caused by ORGs. However, there is still a lack of effective strategies to prevent and delay the occurrence and development of ORG. Therefore, a deeper understanding and elaboration of the pathogenesis of ORG is conducive to the development of therapeutic drugs for ORG. Here, we review the characteristics of pathological lesions of ORG and describe the roles of lipid metabolism disorders and mitochondrial oxidative stress in the development of ORG. Finally, we summarize the current available drugs or compounds for the treatment of ORG and suggested that ameliorating renal lipid metabolism and mitochondrial function may be potential therapeutic targets for ORG.

Normal diet ameliorates obesity more safely and effectively than ketogenic diet does in high-fat diet-induced obesity mouse based on gut microbiota and lipid metabolism

Growing evidence supports the efficacy of ketogenic diets for inducing weight loss, but there are also potential health risks due to their unbalanced nutrient composition. We aim at assessing relative effectiveness of a balanced diet and ketogenic diet for reversing metabolic syndrome in a diet-induced C57BL/6J mouse model. Mice were fed high-fat diet to induce obesity. Obese individuals were then fed either ketogenic or balanced diets as an obesity intervention. Serum, liver, fat and faecal samples were analysed. We observed that both diet interventions led to significant decrease in body weight. The ketogenic intervention was less effective in reducing adipocyte cell size and led to dyslipidaemia. The composition of the gut microbiome in the balanced diet intervention was more similar to the non-obese control group and had improved functional attributes. Our results indicate intervention with balanced diets ameliorates obesity more safely and effectively than ketogenic diets in diet-induced obesity mouse model.

Sleep Deprivation and Gut Microbiota Dysbiosis: Current Understandings and Implications

Gut microbiota comprises the microbial communities inhabiting our gastrointestinal (GI) tracts. Accordingly, these complex communities play a fundamental role in many host processes and are closely implicated in human health and diseases. Sleep deprivation (SD) has become increasingly common in modern society, partly owing to the rising pressure of work and the diversification of entertainment. It is well documented that sleep loss is a significant cause of various adverse outcomes on human health including immune-related and metabolic diseases. Furthermore, accumulating evidence suggests that gut microbiota dysbiosis is associated with these SD-induced human diseases. In this review, we summarize the gut microbiota dysbiosis caused by SD and the succedent diseases ranging from the immune system and metabolic system to various organs and highlight the critical roles of gut microbiota in these diseases. The implications and possible strategies to alleviate SD-related human diseases are also provided.

Controlled light exposure and intermittent fasting as treatment strategies for metabolic syndrome and gut microbiome dysregulation in night shift workers

The mammalian circadian clocks are entrained by environmental time cues, such as the light-dark cycle and the feeding-fasting cycle. In modern society, circadian misalignment is increasingly more common under the guise of shift work. Shift workers, accounting for roughly 20% of the workforce population, are more susceptible to metabolic disease. Exposure to artificial light at night and eating at inappropriate times of the day uncouples the central and peripheral circadian clocks. This internal circadian desynchrony is believed to be one of the culprits leading to metabolic disease. In this review, we discuss how alterations in the rhythm of gut microbiota and their metabolites during chronodisruption send conflicting signals to the host, which may ultimately contribute to disturbed metabolic processes. We propose two behavioral interventions to improve health in shift workers. Firstly, by carefully timing the moments of exposure to blue light, and hence shifting the melatonin peak, to improve sleep quality of daytime sleeping episodes. Secondly, by timing the daily time window of caloric intake to the biological morning, to properly align the feeding-fasting cycle with the light-dark cycle and to reduce the risk of metabolic disease. These interventions can be a first step in reducing the worldwide burden of health problems associated with shift work.

Review: Gestational and postnatal nutritional effects on the neuroendocrine control of puberty and subsequent reproductive performance in heifers

Pubertal attainment is an intricate biological process that involves maturation of the reproductive neuroendocrine axis and increased pulsatile release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone. Nutrition is a critical environmental factor controlling the timing of puberty attainment. Nutrient restriction during early postnatal development delays puberty, whereas increased feed intake and adiposity during this period hasten pubertal maturation by imprinting the hypothalamus. Moreover, the dam's nutrition during gestation can program the neuroendocrine system in the developing fetus and has the potential to advance or delay puberty in the offspring. Leptin, a hormone produced primarily by adipose cells, plays an important role in communicating energy status to the brain and regulating sexual maturation. Leptin's regulation of GnRH release is mediated by an upstream neuronal network since GnRH neurons do not contain the leptin receptor. Two groups of neurons located in the arcuate nucleus of the hypothalamus that express neuropeptide Y (NPY), an orexigenic peptide, and alpha melanocyte-stimulating hormone (αMSH), an anorexigenic peptide, are central elements of the neural circuitry that relay inhibitory (NPY) and excitatory (αMSH) inputs to GnRH neurons. Moreover, KNDy neurons, neurons in the arcuate nucleus that co-express kisspeptin, neurokinin B (NKB), and dynorphin, also play a role in the metabolic regulation of puberty. Our studies in beef heifers demonstrate that increased rates of BW gain during early postweaning (4-9 mo of age) result in reduced expression of NPY mRNA, increased expression of proopiomelanocortin and kisspeptin receptor mRNA, reduced NPY inhibitory inputs to GnRH neurons, and increased excitatory αMSH inputs to KNDy neurons. Finally, our most recent data demonstrate that nutrition of the cow during the last two trimesters of gestation can also induce transcriptional and structural changes in hypothalamic neurocircuitries in the heifer progeny that likely persist long-term after birth. Managerial approaches, such as supplementation of the dam during gestation (fetal programming), creep feeding, early weaning, and stair-step nutritional regimens have been developed to exploit brain plasticity and advance pubertal maturation in heifers.

The Role of Selected Adipocytokines in Ovarian Cancer and Endometrial Cancer

Due to their multidirectional influence, adipocytokines are currently the subject of numerous intensive studies. Significant impact applies to many processes, both physiological and pathological. Moreover, the role of adipocytokines in carcinogenesis seems particularly interesting and not fully understood. For this reason, ongoing research focuses on the role of these compounds in the network of interactions in the tumor microenvironment. Particular attention should be drawn to cancers that remain challenging for modern gynecological oncology-ovarian and endometrial cancer. This paper presents the role of selected adipocytokines, including leptin, adiponectin, visfatin, resistin, apelin, chemerin, omentin and vaspin in cancer, with a particular focus on ovarian and endometrial cancer, and their potential clinical relevance.

Maternal obesity and ovarian failure: is leptin the culprit?

At the time of its discovery and characterization in 1994, leptin was mostly considered a metabolic hormone able to regulate body weight and energy homeostasis. However, in recent years, a great deal of literature has revealed leptin's pleiotropic nature, through its involvement in numerous physiological contexts including the regulation of the female reproductive tract and ovarian function. Obesity has been largely associated with infertility, and leptin signalling is known to be dysregulated in the ovaries of obese females. Hence, the disruption of ovarian leptin signalling was shown to contribute to the pathophysiology of ovarian failure in obese females, affecting transcriptional programmes in the gamete and somatic cells. This review attempts to uncover the underlying mechanisms contributing to female infertility associated with obesity, as well as to shed light on the role of leptin in the metabolic dysregulation within the follicle, the effects on the oocyte epigenome, and the potential long-term consequence to embryo programming.

Synthesis, Regulatory Factors, and Signaling Pathways of Estrogen in the Ovary

New insights have been thrown for understanding the significant role of estrogen on various systems of humans. Increasing evidences have determined the significant roles of estrogen in female reproductive system. So, the normal synthesis and secretion of estrogen play important roles in maintaining the function of tissues and organs. The ovaries are the main synthetic organs of estrogen. In this review, we summarized the current knowledge of the estrogen synthesis in the ovaries. A series of factors and signaling pathways that regulate the synthesis of estrogen are expounded in detail. Understanding the regulating factors and potential mechanism related to estrogen synthesis will be beneficial for understanding estrogen disorder related diseases and may provide novel therapeutic targets.

Recent Advances in the Knowledge of the Mechanisms of Leptin Physiology and Actions in Neurological and Metabolic Pathologies

Excess body weight is frequently associated with low-grade inflammation. Evidence indicates a relationship between obesity and cancer, as well as with other diseases, such as diabetes and non-alcoholic fatty liver disease, in which inflammation and the actions of various adipokines play a role in the pathological mechanisms involved in these disorders. Leptin is mainly produced by adipose tissue in proportion to fat stores, but it is also synthesized in other organs, where leptin receptors are expressed. This hormone performs numerous actions in the brain, mainly related to the control of energy homeostasis. It is also involved in neurogenesis and neuroprotection, and central leptin resistance is related to some neurological disorders, e.g., Parkinson's and Alzheimer's diseases. In peripheral tissues, leptin is implicated in the regulation of metabolism, as well as of bone density and muscle mass. All these actions can be affected by changes in leptin levels and the mechanisms associated with resistance to this hormone. This review will present recent advances in the molecular mechanisms of leptin action and their underlying roles in pathological situations, which may be of interest for revealing new approaches for the treatment of diseases where the actions of this adipokine might be compromised.

Obesity and chronic kidney disease

The prevalence of obesity has increased dramatically during the past decades, which has been a major health problem. Since 1975, the number of people with obesity worldwide has nearly tripled. An increasing number of studies find obesity as a driver of chronic kidney disease (CKD) progression, and the mechanisms are complex and include hemodynamic changes, inflammation, oxidative stress, and activation of the renin-angiotensin-aldosterone system (RAAS). Obesity-related kidney disease is characterized by glomerulomegaly, which is often accompanied by localized and segmental glomerulosclerosis lesions. In these patients, the early symptoms are atypical, with microproteinuria being the main clinical manifestation and nephrotic syndrome being rare. Weight loss and RAAS blockers have a protective effect on obesity-related CKD, but even so, a significant proportion of patients eventually progress to end-stage renal disease despite treatment. Thus, it is critical to comprehend the mechanisms underlying obesity-related CKD to create new tactics for slowing or stopping disease progression. In this review, we summarize current knowledge on the mechanisms of obesity-related kidney disease, its pathological changes, and future perspectives on its treatment.

Eight Weeks of Vitamin C Supplementation Restores the Lost Correlation between Serum Leptin and C-reactive Protein (CRP) in Patients with Type 2 Diabetes; A Randomized, Double-blind, Parallel-group, Placebo-controlled Clinical Trial

OBJECTIVE

Inflammation is a well-described factor in the pathophysiology of type 2 diabetes mellitus (DM), which has been a suspect in the alteration of correlations between CRP and leptin in patients with type 2 DM.

AIM

This study aimed to show the effect of vitamin C as an antioxidant on the correlation of the serum levels of C-reactive protein (CRP) and leptin in patients with type 2 DM.

METHODS

We recruited 70 patients with longstanding T2DM and randomly assigned them into two groups; one received 500 mg/day of vitamin C, and the other received a placebo for eight weeks. Both groups were matched regarding baseline characteristics such as age, gender, weight, and diabetic medications.

RESULTS

Out of 70 individuals, 57 participants were left in the study. After eight weeks of follow-up, leptin level was significantly increased in the Vitamin C group (MD = 3.48 change = 24%, p-value = 0.001) but did not change in the placebo group. Other markers such as Fasting plasma glucose, HbA1c, Creatinine, uric acid, Urea, cholesterol, HDL, LDL, TG, AST, ALT, insulin, and CRP did not significantly change in both groups (p value > 0.05). The significant changes in the leptin level among the vitamin C group also remained after controlling for age, BMI, Blood pressure (BP), Triglyceride (TG), and cholesterol. Also, the correlation between serum CRP and leptin became significant in the vitamin C group after eight weeks of follow-up but not in the placebo group. (rs = 0.730, p < 0.001 vs. rs = 0.286, p-value = 0.266 in placebo group).

CONCLUSION

This study shows vitamin C can restore CRP-leptin correlation in patients with type 2 diabetes and increase serum leptin levels. More studies are needed to clarify the mechanism of this restoration.

CLINICAL TRIAL REGISTRATION NUMBER

IRCT20160811029306N1.

Emerging roles of leptin in Parkinson's disease: Chronic inflammation, neuroprotection and more?

An increasing body of experimental evidence implicates a relationship between immunometabolic deterioration and the progression of Parkinson's disease (PD) with a dysregulation of central and peripheral neuroinflammatory networks mediated by circulating adipokines, in particular leptin. We screened the current literature on the role of adipokines in PD. Hence, we searched known databases (PubMed, MEDLINE/OVID) and reviewed original and review articles using the following terms: "leptin/ObR", "Parkinson's disease", "immune-metabolism", "biomarkers" and "neuroinflammation". Focusing on leptin, we summarize and discuss the existing in vivo and in vitro evidence on how adipokines may be protective against neurodegeneration, but at the same time contribute to the progression of PD. These components of the adipose brain axis represent a hitherto underestimated pathway to study systemic influences on dopaminergic degeneration. In addition, we give a comprehensive update on the potential of adjunctive therapeutics in PD targeting leptin, leptin-receptors, and associated pathways. Further experimental and clinical trials are needed to elucidate the mechanisms of action and the value of central and peripheral adipose-immune-metabolism molecular phenotyping in order to develop and validate the differential roles of different adipokines as potential therapeutic target for PD patients.

Bioinformatics analysis of candidate genes and potential therapeutic drugs targeting adipose tissue in obesity

Obesity is a complex medical condition that affects multiple organs in the body. However, the underlying mechanisms of obesity, as well as its treatment, are largely unexplored. The focus of this research was to use bioinformatics to discover possible treatment targets for obesity. To begin, the GSE133099 database was used to identify 364 differentially expressed genes (DEGs). Then, DEGs were subjected to tissue-specific analyses and enrichment analyses, followed by the creation of a protein-protein interaction (PPI) network and generation of a drug-gene interaction database to screen key genes and potential future drugs targeting obesity. Findings have illustrated that the tissue-specific expression of neurologic markers varied significantly (34.7%, 52/150). Among these genes, Lep, ApoE, Fyn, and FN1 were the key genes observed in the adipocyte samples from obese patients relative to the controls. Furthermore, nine potential therapeutic drugs (dasatinib, ocriplasmin, risperidone, gemfibrozil, ritonavir, fluvastatin, pravastatin, warfarin, atorvastatin) that target the key genes were also screened and selected. To conclude the key genes discovered (Lep, ApoE, Fyn, and FN1), as well as 9 candidate drugs, could be used as therapeutic targets in treating obesity.

Capillary Vibrating Sharp-Edge Spray Ionization Augments Field-Free Ionization Techniques to Promote Conformer Preservation in the Gas-Phase for Intractable Biomolecular Ions

Field-free capillary vibrating sharp-edge spray ionization (cVSSI) is evaluated for its ability to conduct native mass spectrometry (MS) experiments. The charge state distributions for nine globular proteins are compared using field-free cVSSI, field-enabled cVSSI, and electrospray ionization (ESI). In general, for both positive and negative ion mode, the average charge state (qavg) increases for field-free cVSSI with increasing molecular weight similar to ESI. A clear difference is that the qavg is significantly lower for field-free conditions in both analyses. Two proteins, leptin and thioredoxin, exhibit bimodal charge state distributions (CSDs) upon the application of voltage in positive ion mode; only a monomodal distribution is observed for field-free conditions. In negative ion mode, thioredoxin exhibits a multimodal CSD upon the addition of voltage to cVSSI. Extensive molecular dynamics (MD) simulations of myoglobin and leptin in nanodroplets suggest that the multimodal CSD for leptin may originate from increased conformational "breathing" (decreased packing) and association with the droplet surface. These properties along with increased droplet charge appear to play critical roles in shifting ionization processes for some proteins. Further exploration and development of field-free cVSSI as a new ionization source for native MS especially as applied to more flexible biomolecular species is warranted.

Adipokines as Regulators of Autophagy in Obesity-Linked Cancer

Excess body weight and obesity have become significant risk factors for cancer development. During obesity, adipose tissue alters its biological function, deregulating the secretion of bioactive factors such as hormones, cytokines, and adipokines that promote an inflammatory microenvironment conducive to carcinogenesis and tumor progression. Adipokines regulate tumor processes such as apoptosis, proliferation, migration, angiogenesis, and invasion. Additionally, it has been found that they can modulate autophagy, a process implicated in tumor suppression in healthy tissue and cancer progression in established tumors. Since the tumor-promoting role of autophagy has been well described, the process has been suggested as a therapeutic target in cancer. However, the effects of targeting autophagy might depend on the tumor type and microenvironmental conditions, where circulating adipokines could influence the role of autophagy in cancer. Here, we review recent evidence related to the role of adipokines in cancer cell autophagy in an effort to understand the tumor response in the context of obesity under the assumption of an autophagy-targeting treatment.

Epidemiology of Breast Cancer in Mexican Women with Obesity as a Risk Factor

Purpose. Adipose tissue in overweight and obesity shows metabolic imbalance in the function of adipocytes and macrophages, this leads to altered regulation of hunger, lipid storage, and chronic inflammation possibly related to the development of breast cancer. Methods. The study was retrospective of 653 breast cancer patients treated at a tertiary care hospital. Histopathology, hormone receptors, grade, clinical stage, clinical biometry analysis, CEA and CA 15-3 antigens were analyzed. The analyses were performed at diagnosis and at the end of oncological treatments. Results. Mexican women studied and treated for breast cancer have an BMI of 29 from diagnosis and at the end of their cancer treatments. The average age was 52 ± 12 years, 54% in women older than 55 years. Cancer recurrence occurs in any molecular type; however, the common factor was overweight and obesity with 73% vs. 21% in normal weight patients. The most frequent tumor tissue in the population was positive hormone receptors of the luminal type (65%), HER2 (15%), and NT (15%). The analyses of macrophages/lymphocytes (M/L), CEA, and CA 15-3 antigens evaluated in women >55 and <55 years, with and without recurrence are elevated at the end of oncological treatments. Conclusions. The analysis of Mexican women with breast cancer showed a predominance of overweight and obesity at diagnosis and at the end of treatment. A relationship between obesity and cancer recurrence with a low response to treatment due to elevation in Ag CEA and CA 15-3 is suggested. The L/M ratio could be an indicator of inflammation related to adipose tissue since diagnosis.

Adiponectin, leptin, and leptin/adiponectin ratio with risk of gestational diabetes mellitus: A prospective nested case-control study among Chinese women

AIMS

To examine the associations of serum concentrations of adiponectin and leptin and leptin/adiponectin ratio (LAR) in early pregnancy with risk of gestational diabetes mellitus (GDM) in Chinese women. The predictive ability of those biomarkers for GDM was also assessed.

METHODS

Within the Tongji-Shuangliu Birth Cohort, a nested case-control study was established with 332 GDM cases and 664 matched controls at 1:2 ratio on age (±3 years) and gestational age (±4 weeks). Serum adiponectin and leptin levels were measured in early pregnancy (median gestational week, 11; range, 6-15). Conditional logistic regression models with adjustment for potential covariates were used to evaluate the associations.

RESULTS

Multivariable-adjusted odds ratios (ORs) comparing extreme quartiles of adiponectin, leptin and LAR were 0.55 (95 % CI, 0.35, 0.85), 1.96 (95 % CI, 1.19, 3.24), and 2.72 (95 % CI, 1.63, 4.54) for GDM, respectively (All P-trend < 0.02). Adding adiponectin and leptin to a conventional prediction model (including traditional risk factors and fasting glucose) increased the C-statistics from 0.708 (95 % CI, 0.674, 0.741) to 0.728 (95 % CI, 0.695, 0.760), and achieved a net reclassification improvement of 0.292.

CONCLUSIONS

Our findings indicate that adiponectin is inversely associated with GDM, while leptin and LAR are positively associated with GDM in Chinese pregnant women.

SINE Insertion May Act as a Repressor to Affect the Expression of Pig LEPROT and Growth Traits

Retrotransposon is an important component of the mammalian genome. Previous studies have shown that the expression of protein-coding genes was affected by the insertion of retrotransposon into the proximal genes, and the phenotype variations would be related to the retrotransposon insertion polymorphisms (RIPs). In this study, leptin (LEP), leptin receptor (LEPR), and leptin receptor overlapping transcript (LEPROT), which play important roles in the regulation of fat synthesis and body weight, were screened to search for the RIPs and their effect on phenotype and gene expression, as well as to further study the function of the insertion. The results showed that three RIPs located in intron 1 of LEPROT and intron 2 and 21 of LEPR were identified, and they were all SINEA1, which was one type of retrotransposon. The SINE insertion at the LEPROT was the dominant allele in native pig breeds. The age of 100 kg body weight of SINE+/+ Large White individuals was significantly higher than those of SINE+/− and SINE−/− individuals (p < 0.05). The LEPROT gene expression in the liver and suet of 30-day-old SINE−/− Sujiang piglets were significantly higher than those of SINE+/+ and SINE+/− piglets (p < 0.01). The dual-luciferase reporter gene assay showed that SINE insertion in PK15 and 3T3-L1 cells significantly reduced the promoter activity of the LEPROT gene (p < 0.01). Therefore, SINE insertion can be a repressor to reduce the expression of LEPROT and could be a useful molecular marker for assisted selection of growth traits in pig breeding.

A High-Sugar Diet Consumption, Metabolism and Health Impacts with a Focus on the Development of Substance Use Disorder: A Narrative Review

Carbohydrates are important macronutrients in human and rodent diet patterns that play a key role in crucial metabolic pathways and provide the necessary energy for proper body functioning. Sugar homeostasis and intake require complex hormonal and nervous control to proper body energy balance. Added sugar in processed food results in metabolic, cardiovascular, and nervous disorders. Epidemiological reports have shown enhanced consumption of sweet products in children and adults, especially in reproductive age and in pregnant women, which can lead to the susceptibility of offspring's health to diseases in early life or in adulthood and proneness to mental disorders. In this review, we discuss the impacts of high-sugar diet (HSD) or sugar intake during the perinatal and/or postnatal periods on neural and behavioural disturbances as well as on the development of substance use disorder (SUD). Since several emotional behavioural disturbances are recognized as predictors of SUD, we also present how HSD enhances impulsive behaviour, stress, anxiety and depression. Apart from the influence of HSD on these mood disturbances, added sugar can render food addiction. Both food and addictive substances change the sensitivity of the brain rewarding neurotransmission signalling. The results of the collected studies could be important in assessing sugar intake, especially via maternal dietary patterns, from the clinical perspective of SUD prevention or pre-existing emotional disorders. Methodology: This narrative review focuses on the roles of a high-sugar diet (HSD) and added sugar in foods and on the impacts of glucose and fructose on the development of substance use disorder (SUD) and on the behavioural predictors of drugs abuse. The literature was reviewed by two authors independently according to the topic of the review. We searched the PubMed and Scopus databases and Multidisciplinary Digital Publishing Institute open access scientific journals using the following keyword search strategy depending on the theme of the chapter: "high-sugar diet" OR "high-carbohydrate diet" OR "sugar" OR "glucose" OR "fructose" OR "added sugar" AND keywords. We excluded inaccessible or pay-walled articles, abstracts, conference papers, editorials, letters, commentary, and short notes. Reviews, experimental studies, and epidemiological data, published since 1990s, were searched and collected depending on the chapter structure. After the search, all duplicates are thrown out and full texts were read, and findings were rescreened. After the selection process, appropriate papers were included to present in this review.

Patch-to-Seq and Transcriptomic Analyses Yield Molecular Markers of Functionally Distinct Brainstem Serotonin Neurons

Acute regulation of CO₂ and pH homeostasis requires sensory feedback from peripheral (carotid body) and central (central) CO₂/pH sensitive cells - so called respiratory chemoreceptors. Subsets of brainstem serotonin (5-HT) neurons in the medullary raphe are CO₂ sensitive or insensitive based on differences in embryonic origin, suggesting these functionally distinct subpopulations may have unique transcriptional profiles. Here, we used Patch-to-Seq to determine if the CO₂ responses in brainstem 5-HT neurons could be correlated to unique transcriptional profiles and/or unique molecular markers and pathways. First, firing rate changes with hypercapnic acidosis were measured in fluorescently labeled 5-HT neurons in acute brainstem slices from transgenic, Dahl SS (SSMcwi) rats expressing T2/ePet-eGFP transgene in Pet-1 expressing (serotonin) neurons (SS ^ePet1-eGFP rats). Subsequently, the transcriptomic and pathway profiles of CO₂ sensitive and insensitive 5-HT neurons were determined and compared by single cell RNA (scRNAseq) and bioinformatic analyses. Low baseline firing rates were a distinguishing feature of CO₂ sensitive 5-HT neurons. scRNAseq of these recorded neurons revealed 166 differentially expressed genes among CO₂ sensitive and insensitive 5-HT neurons. Pathway analyses yielded novel predicted upstream regulators, including the transcription factor Egr2 and Leptin. Additional bioinformatic analyses identified 6 candidate gene markers of CO₂ sensitive 5-HT neurons, and 2 selected candidate genes (CD46 and Iba57) were both expressed in 5-HT neurons determined via in situ mRNA hybridization. Together, these data provide novel insights into the transcriptional control of cellular chemoreception and provide unbiased candidate gene markers of CO₂ sensitive 5-HT neurons. Methodologically, these data highlight the utility of the patch-to-seq technique in enabling the linkage of gene expression to specific functions, like CO₂ chemoreception, in a single cell to identify potential mechanisms underlying functional differences in otherwise similar cell types.

Adipokines in Sleep Disturbance and Metabolic Dysfunction: Insights from Network Analysis

Adipokines are a growing group of secreted proteins that play important roles in obesity, sleep disturbance, and metabolic derangements. Due to the complex interplay between adipokines, sleep, and metabolic regulation, an integrated approach is required to better understand the significance of adipokines in these processes. In the present study, we created and analyzed a network of six adipokines and their molecular partners involved in sleep disturbance and metabolic dysregulation. This network represents information flow from regulatory factors, adipokines, and physiologic pathways to disease processes in metabolic dysfunction. Analyses using network metrics revealed that obesity and obstructive sleep apnea were major drivers for the sleep associated metabolic dysregulation. Two adipokines, leptin and adiponectin, were found to have higher degrees than other adipokines, indicating their central roles in the network. These adipokines signal through major metabolic pathways such as insulin signaling, inflammation, food intake, and energy expenditure, and exert their functions in cardiovascular, reproductive, and autoimmune diseases. Leptin, AMP activated protein kinase (AMPK), and fatty acid oxidation were found to have global influence in the network and represent potentially important interventional targets for metabolic and sleep disorders. These findings underscore the great potential of using network based approaches to identify new insights and pharmaceutical targets in metabolic and sleep disorders.

Plasma concentration of Bisphenol A and leptin in patients with meningioma and glioma: A pilot study

PURPOSE

Recent increase in incidence of meningiomas suggests the need to search for new risk factors. Leptin, a potentially pro-angiogenic and proliferative agent, could be a candidate for this role, as its expression correlates with body mass index (BMI). Because development of meningioma has also been linked to sex hormones, bisphenol A (BPA), a known xenoestrogen, can also be taken into consideration as a potential risk factor. The aim of this study was to determine plasma concentrations of both substances in patients with meningiomas and to match it to patients with gliomas - a group of brain tumors less hormone- and BMI-dependent.

MATERIALS & METHODS

Concentrations of BPA and leptin were measured in plasma of 24 patients with low grade meningioma and in 29 patients with glioma, using gas chromatography-mass spectrometry (GC-MS) and ELISA kits, respectively. The concentrations of both substances in patients with neoplasms were interpreted in relation to their concentration in healthy population, published in recent reports.

RESULTS

Free and conjugated BPA were present in both meningioma and glioma patients. Moreover, their concentrations far exceeded those reported in the healthy population. Nevertheless, the level of leptin revealed to be significantly higher in meningioma patients than in glioma patients.

CONCLUSIONS

Occurrence of both meningioma and glioma may be accompanied by increased concentrations of leptin and BPA. Further large-scale studies are needed to clarify whether the presence of both substances may play a role in pathogenesis or influence clinical course in patients with brain neoplasms.

The Head-to-Toe Hormone: Leptin as an Extensive Modulator of Physiologic Systems

Leptin is a well-known hunger-sensing peptide hormone. The role of leptin in weight gain and metabolic homeostasis has been explored for the past two decades. In this review, we have tried to shed light upon the impact of leptin signaling on health and diseases. At low or moderate levels, this peptide hormone supports physiological roles, but at chronically higher doses exhibits detrimental effects on various systems. The untoward effects we observe with chronically higher levels of leptin are due to their receptor-mediated effect or due to leptin resistance and are not well studied. This review will help us in understanding the non-anorexic roles of leptin, including their contribution to the metabolism of various systems and inflammation. We will be able to get an alternative perspective regarding the physiological and pathological roles of this mysterious peptide hormone.

β-Klotho promotes glycolysis and glucose-stimulated insulin secretion via GP130

Impaired glucose-stimulated insulin secretion (GSIS) is a hallmark of type-2 diabetes. However, cellular signaling machineries that control GSIS remain incompletely understood. Here, we report that β-klotho (KLB), a single-pass transmembrane protein known as a co-receptor for fibroblast growth factor 21 (FGF21), fine tunes GSIS via modulation of glycolysis in pancreatic β-cells independent of the actions of FGF21. β-cell-specific deletion of Klb but not Fgf21 deletion causes defective GSIS and glucose intolerance in mice and defective GSIS in islets of type-2 diabetic mice is mitigated by adenovirus-mediated restoration of KLB. Mechanistically, KLB interacts with and stabilizes the cytokine receptor subunit GP130 by blockage of ubiquitin-dependent lysosomal degradation, thereby facilitating interleukin-6-evoked STAT3-HIF1α signaling, which in turn transactivates a cluster of glycolytic genes for adenosine triphosphate production and GSIS. The defective glycolysis and GSIS in Klb-deficient islets are rescued by adenovirus-mediated replenishment of STAT3 or HIF1α. Thus, KLB functions as a key cell-surface regulator of GSIS by coupling the GP130 receptor signaling to glucose catabolism in β-cells and represents a promising therapeutic target for diabetes.

New Aspects of Corpus Luteum Regulation in Physiological and Pathological Conditions: Involvement of Adipokines and Neuropeptides

The corpus luteum is a small gland of great importance because its proper functioning determines not only the appropriate course of the estrous/menstrual cycle and embryo implantation, but also the subsequent maintenance of pregnancy. Among the well-known regulators of luteal tissue functions, increasing attention is focused on the role of neuropeptides and adipose tissue hormones-adipokines. Growing evidence points to the expression of these factors in the corpus luteum of women and different animal species, and their involvement in corpus luteum formation, endocrine function, angiogenesis, cells proliferation, apoptosis, and finally, regression. In the present review, we summarize the current knowledge about the expression and role of adipokines, such as adiponectin, leptin, apelin, vaspin, visfatin, chemerin, and neuropeptides like ghrelin, orexins, kisspeptin, and phoenixin in the physiological regulation of the corpus luteum function, as well as their potential involvement in pathologies affecting the luteal cells that disrupt the estrous cycle.

Leptin in Osteoarthritis and Rheumatoid Arthritis: Player or Bystander?

White adipose tissue (WAT) is a specialized tissue whose main function is lipid synthesis and triglyceride storage. It is now considered as an active organ secreting a plethora of hormones and cytokines namely adipokines. Discovered in 1994, leptin has emerged as a key molecule with pleiotropic functions. It is primarily recognized for its role in regulating energy homeostasis and food intake. Currently, further evidence suggests its potent role in reproduction, glucose metabolism, hematopoiesis, and interaction with the immune system. It is implicated in both innate and adaptive immunity, and it is reported to contribute, with other adipokines, in the cross-talking networks involved in the pathogenesis of chronic inflammation and immune-related diseases of the musculo-skeletal system such as osteoarthritis (OA) and rheumatoid arthritis (RA). In this review, we summarize the most recent findings concerning the involvement of leptin in immunity and inflammatory responses in OA and RA.

Short-term ozone exposure and metabolic status in metabolically healthy obese and normal-weight young adults: A viewpoint of inflammatory pathways

Unhealthy metabolic status increases risks of cardiovascular and other diseases. This study aims to explore whether there is a link between O₃ and metabolic health indicators through a viewpoint of inflammatory pathways. 49 metabolically healthy normal-weight (MH-NW) and 39 metabolically healthy obese (MHO) young adults aged 18-26 years were recruited from a panel study with three visits. O₃ exposure were estimated based on fixed-site environmental monitoring data and time-activity diary for each participant. Compared to MH-NW people, MHO people were more susceptible to the adverse effects on metabolic status, including blood pressure, glucose, and lipid indicators when exposed to O₃. For instance, O₃ exposure was associated with significant decreases in high-density lipoprotein cholesterol (HDL-C), and increases in C-peptide and low-density lipoprotein cholesterol (LDL-C) among MHO people, while only weaker changes in HDL-C and LDL-C among MH-NW people. Mediation analyses indicated that leptin mediated the metabolic health effects in both groups, while eosinophils and MCP-1 were also important mediating factors for the MHO people. Although both with a metabolically healthy status, compared to normal-weight people, obese people might be more susceptible to the negative effects of O₃ on metabolic status, possibly through inflammatory indicators such as leptin, eosinophils, and MCP-1.