Are spexin levels associated with metabolic syndrome, dietary intakes and body composition in children?

Associations between food insecurity with gestational diabetes mellitus and maternal outcomes mediated by dietary diversity: A cross-sectional study

BACKGROUND

Food insecurity (FI) during pregnancy negatively impacts maternal health and raises the risk of gestational diabetes mellitus (GDM) and pregnancy-induced hypertension (PIH), resulting in adverse outcomes for both mother and baby.

AIM

To investigate the relationships between FI and pregnancy outcomes, particularly GDM and PIH, while also examining the mediating role of the dietary diversity score (DDS).

METHODS

A cross-sectional study was undertaken to examine this relationship, involving 600 pregnant women. Participants were women aged 18 years or older who provided complete data on FI and pregnancy outcomes. The FI was measured via the Household Food Security Survey Module, with GDM defined as fasting plasma glucose levels of ≥ 5.1 mmol/L or a 2-hour oral glucose tolerance test value of ≥ 8.5 mmol/L. The DDS is determined by evaluating one's food consumption based on nine distinct food groups. A logistic regression model was used to explore the relationship between FI and PIH, and GDM.

RESULTS

Seventeen percent of participants reported experiencing FI during pregnancy. The study found a significant association between FI and an elevated risk of GDM [odds ratio (OR) = 3.32, 95%CI: 1.2-5.4]. Once more, food-insecure pregnant women had higher rates of PIH (OR = 0.10, 95%CI: 0.02-0.45) and they also faced a higher likelihood of neonatal complications, such as neonatal intensive care unit’s admissions and the birth of infants with extremely low birth weight. The FI was further linked to metabolic disruptions, such as elevated fasting blood sugar (FBS), low-density lipoprotein cholesterol, and triglyceride levels. Our results indicate that the DDS acts as a significant mediator in the relationship between FI and the incidence of GDM. In particular, the mediation analysis showed that approximately 65% of the effect was mediated through DDS (P = 0.002).

CONCLUSION

These findings underscore the serious challenges that FI presents during pregnancy and its effects on maternal and infant health. Additionally, the study explored how DDS mediates the relationship between FI and the incidence of GDM.

The Effect of Exercise on Spexin and Follistatin in Elderly Individuals

BACKGROUND

In adipose tissue-muscle crosstalk mechanisms, the interaction of adipokines and myokines is known to be critical for maintaining the body's metabolic balance in age-related metabolic disorders. The aim of the study investigate the effects of 12 weeks of aerobic and resistance exercise training on spexin and follistatin and their relationship with each other.

METHODS

This study was a multicentre, randomized controlled study conducted at two assisted living facilities with participants aged ≥ 65. Among the 66 subjects, 33 were allocated to the exercise group (E) and 33 to the control group (C). The exercise group was administered 50 min of exercise by expert physiotherapists 1 day a week for 12 weeks. Participants in the intervention groups performed exercise assignments two extra days a week, tailored to their specific circumstances and supervised by the institution's physiotherapists. Spexin, follistatin and measurements of metabolic syndrome parameters were performed at the beginning and after 12 weeks.

RESULTS

The mean age of the 62 participants who completed the study (E n = 31, C n = 31) was 73.25 ± 6.44 years, and 62.9% were female. While spexin (E = 1090.94 ± 533.66, C = 1142.91 ± 550.68 pg/mL, p > 0.05) and follistatin (E = 50.52 ± 24.35, C = 50.00 ± 23.52 ng/mL, p > 0.05) values were similar in the two groups at baseline, the values of spexin (E = 1311.32 ± 513.66, C = 1033.27 ± 486.48, p < 0.0001; η2 = 0.387) and follistatin (E = 64.79 ± 32.35, C = 48.16 ± 26.27, p < 0.0001; η2 = 0.267) in the exercise group were higher than in the control group at week 12. At the 12th week, neck circumference (38.32 ± 3.41, 37.16 ± 3.15, p = 0.002), waist circumference (102.64 ± 13.38, 98.54 ± 14.47, p < 0.0001), hip circumference (105.70 ± 15.43, 102.93 ± 13.48, p < 0.0001), body fat mass (22.69 ± 7.39, 20.45 ± 6.22, p < 0.0001) and systolic and diastolic blood pressure (137.19 ± 13.80, 124.9 ± 15.18, p = 0.0001, 77.38 ± 12.10, 72.61 ± 9.26, p = 0.043) decreased, and body muscle mass (46.32 ± 8.43, 49.03 ± 8.58, p < 0.0001) increased in the exercise group compared to baseline. A correlation was observed between the change in follistatin level and the change in spexin level (r = 0.438, p = 0.001). A negative correlation was found between the amount of decrease in body fat mass and the decrease in spexin level (r = -0.380, p = 0.005). A positive correlation was found between the increase in body muscle mass and the increase in spexin and follistatin (r = 0.431, p = 0.001; r = 0.490, p < 0.0001, respectively).

CONCLUSIONS

It was found that spexin, which provides metabolic homeostasis, and follistatin, which expresses the increase in muscle mass, increased with the implementation of a 12-week aerobic and resistance exercise program in elderly individuals, and these increases were found to be associated with each other.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT05251597.

The effects of MIND diet on depression, anxiety, quality of life and metabolic and hormonal status in obese or overweight women with polycystic ovary syndrome: a randomised clinical trial

Polycystic ovary syndrome (PCOS) is a common hormonal disorder in women of reproductive age, associated with increased risks of metabolic disorders, depression and reduced quality of life. This study examined the impact of the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet on mental health, PCOS-related quality of life (PCOSQ), anthropometric indices, hirsutism, and metabolic/hormonal parameters in women with PCOS. Total of 52 women with PCOS, aged between 18 and 45 years, were randomly assigned to either the low calorie MIND diet group or the control group. Anthropometric data, depression and anxiety scores, serum levels of gonadotropins (luteinizing hormone [LH], follicle-stimulating hormone [FSH]), PCOSQ, and Ferriman-Gallwey score were evaluated before and after the intervention. Outcomes were assessed at baseline and at the end of the 8-week follow-up period. After 8 weeks, the MIND diet significantly reduced depression (β -3·03; 95 % CI: [-5·36, -0·70]; P = 0·011) and anxiety (β -3·54; 95 % CI: [-6·60, -0·49]; P = 0·024) scores compared with the control group. The MIND diet group exhibited significant increases in the emotion (β 0·63; 95 % CI: [0·18, 1·08]; P = 0·007) and body hair (β 0·65; 95 % CI: [0·03, 1·28]; P = 0·04) domains of the PCOSQ compared to the control group. The changes in other parameters did not show significant differences between the two groups. Both the MIND diet and control groups showed improvements in weight and BMI, with a slight advantage for the MIND diet group. These findings suggest that the MIND diet may be beneficial for improving mental health and some aspects of PCOSQ in women with PCOS.

Clinical trial of the effects of postbiotic supplementation on inflammation, oxidative stress, and clinical outcomes in patients with CVA

Background Cerebrovascular accidents (CVAs), or strokes, are major global health concerns associated with oxidative stress, inflammation, and gastrointestinal complications. This study aimed to explore the impact of postbiotic supplementation in CVA patients, specifically in terms of oxidative stress, inflammation, and clinical outcomes, as an alternative to probiotics with potential advantages. Method A prospective, single-center, randomized, controlled trial was conducted with 120 CVA patients in Iran. These patients were admitted to the ICU to assess the severity of their strokes. Patients were randomly assigned to receive either postbiotic supplementation (n = 60) or a placebo (n = 60). Various biomarkers related to oxidative stress, inflammation, and clinical outcomes were assessed. Data on demographic characteristics, nosocomial infections, and laboratory measurements were collected. Gut microbiota analysis was also performed on fecal samples. Results After the 7-day intervention, postbiotic supplementation resulted in significant improvements in inflammatory markers, oxidative stress, and a reduced incidence of pneumonia compared with those in the control group, with the postbiotic group demonstrating notable decreases in the serum IL-1β levels (-1.79; 95% CI: = -2.9 to -0.64, p = 0.002 ), MDA levels (-30.5; 95% CI: -54.8 to -6.1, p = 0.015), Hs-CRP levels (-0.67; 95% CI:-1.1 to -0.26 mg/dl, p = 0.001) and TAC levels (62.5; 95%CI: 34.1 to 90.9, p < 0.001) compared with those in the placebo group. However, no significant differences in other clinical outcomes, including the NIHSS score, NUTRIC score, and APACHE II score, or the gut microbiota profile, were observed between the two groups. Conclusion Postbiotic supplementation improved the levels of inflammatory factors and oxidative stress markers and reduced the risk of pneumonia in CVA patients. Trial registration This trial is registered in the Iranian Registry of Clinical Trials (registration code IRCT20180712040438N7), Registration date 06122022.

Comparing sedation protocols for endoscopic retrograde cholangiopancreatography (ERCP): A retrospective study

Background

Endoscopic retrograde cholangiopancreatography (ERCP) is a widely used diagnostic and therapeutic procedure. Effective sedation is crucial to enhance patient comfort and optimize endoscopist performance. Various sedation protocols, including Propofol and Dexmedetomidine (Pro-Dex), Ketamine and Propofol (Keto-Fol), Propofol and Midazolam (Pro-Mid), and Propofol alone, have been utilized during ERCP. This retrospective study aims to compare the safety and efficacy of these four sedation protocols.

Methods

A retrospective analysis was conducted on data from 600 patients who underwent ERCP between 2018 and 2021, with each patient receiving one of the four sedation protocols. Protocol assignment was based on the endoscopist's preference. Data on hemodynamic parameters, sedation level, recovery time, and procedure-related complications were collected.

Results

Baseline data showed no significant differences among the groups pre-procedure. The Pro-Dex group exhibited significantly lower mean total propofol dose, shorter recovery time, and faster achievement of Ramsay Sedation Scale (RSS) score 3-4 compared to the other groups. The Pro-group demonstrated significantly longer hospital stay than the other three groups (median, 4.19 ± 1.1 vs. 3.48 ± 1.2 days in the KP groups, p = 0.042). There were no significant variations in the incidence of respiratory depression, hypotension, or bradycardia among the four groups. Additionally, notable trends were found for hemodynamic measures, total propofol dosage, time to reach the desired level of sedation (as measured by the Ramsay Sedation Scale), and hospital stay based on BMI categories, indicating that higher BMI is linked to more serious outcomes.

Conclusion

Our retrospective study demonstrates that the Pro-Dex protocol offers superior sedation quality, faster recovery, and fewer complications compared to the other protocols during ERCP. However, the incidence of ERCP-related adverse events did not significantly differ among the four sedation protocols. These findings can aid clinicians in selecting the most appropriate sedation protocol for ERCP, considering patient and endoscopist preferences.

Protective Effect of N-Acetylcysteine Against Aluminum-Induced Kidney Tissue Damage in Rats

Aluminum (AL) is an important nephrotoxic agent with a high daily exposure rate and property of accumulation in tissues. This study aimed to investigate the potential protective efficacy of N-acetylcysteine (NAC) against AL exposure-induced nephrotoxicity in rats. Twenty-eight rats were randomly divided into 4 groups as control, N-acetylcysteine group (NC), AL, and AL + NC, with an equal number of rats in each group (n = 7). No application was made to the control group. A total of 150 mg/kg/day NAC was administered to the NC group and 30 mg/kg/day AL was administered to the AL group intraperitoneally (i.p.). The AL + NC group received 30 mg/kg/day AL and 150 mg/kg/day NAC i.p. Biochemical parameters in blood serum and histopathological changes in kidney tissue, oxidative stress parameters, spexin (SPX), and apoptotic protein levels were examined after 15 days. Histopathological changes, biochemical parameters, oxidative stress parameters, and apoptotic protein levels were significantly irregular in the AL group compared to the control group. Moreover, SPX levels increased in the AL group. However, NAC treatment regulated AL exposure-related changes in the AL + NC group. NAC treatment may have a prophylactic effect against nephrotoxicity due to AL exposure. SPX may play a role in AL-induced nephrotoxicity.

Adipose-Muscle crosstalk in age-related metabolic disorders: The emerging roles of adipo-myokines

Obesity and type 2 diabetes account for a considerable proportion of the global burden of age-related metabolic diseases. In age-related metabolic diseases, tissue crosstalk and metabolic regulation have been primarily linked to endocrine processes. Skeletal muscle and adipose tissue are endocrine organs that release myokines and adipokines into the bloodstream, respectively. These cytokines regulate metabolic responses in a variety of tissues, including skeletal muscle and adipose tissue. However, the intricate mechanisms underlying adipose-muscle crosstalk in age-related metabolic diseases are not fully understood. Recent exciting evidence suggests that myokines act to control adipose tissue functions, including lipolysis, browning, and inflammation, whereas adipokines mediate the beneficial actions of adipose tissue in the muscle, such as glucose uptake and metabolism. In this review, we assess the mechanisms of adipose-muscle crosstalk in age-related disorders and propose that the adipokines adiponectin and spexin, as well as the myokines irisin and interleukin-6 (IL-6), are crucial for maintaining the body's metabolic balance in age-related metabolic disorders. In addition, these changes of adipose-muscle crosstalk in response to exercise or dietary flavonoid consumption are part of the mechanisms of both functions in the remission of age-related metabolic disorders. A better understanding of the intricate relationships between adipose tissue and skeletal muscle could lead to more potent therapeutic approaches to prolong life and prevent age-related metabolic diseases.

Protective and therapeutic effectiveness of taurine supplementation plus low calorie diet on metabolic parameters and endothelial markers in patients with diabetes mellitus: a randomized, clinical trial

Background

Taurine supplementation as a sulfur-containing amino acid may attenuate and/or alleviate diabetes-induced complications and endothelial dysfunction via its anti-inflammatory and antioxidant activities. Our purpose was to investigate the effect of Taurine supplementation on endothelial dysfunction markers, oxidative stress, inflammation, and glycemic control in patients with type 2 diabetes mellitus (T2DM).

Methods

In the current clinical trial, 120 patients with T2DM were randomly allocated to take either Taurine (containing 1 g Taurine, n = 60) or placebo (n = 60) three times per day for an eight-week period. Moreover, all patients were on a low-calorie diet. The primary outcome was fasting blood glucose (FBG) and endothelial markers including sera intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule (VCAM), and matrix metallopeptidase 9 (MMP-9). The secondary outcome was dietary intake, anthropometric indices, serum insulin and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), total antioxidant capacity (TAC), tumor necrosis factor (TNF), high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and lipid profile.

Results

After 8 weeks, Taurine-supplemented patients had a considerable decrease in serum insulin and HOMA-IR compared to placebo group. However, Taurine supplementation did not improve other metabolic parameters including lipid profiles, glycated hemoglobin, and fasting blood glucose (FBG). There was a significant decline in MDA, TNF, and hs-CRP levels after these eight-week period of Taurine supplementation. In addition, the Taurine group had fewer serum levels of endothelial dysfunction markers than the placebo group.

Conclusions

The evidence from our study revealed that Taurine supplementation significantly reduced insulin and HOMA-IR, as well as oxidative stress, inflammation, and endothelial markers in individuals with T2DM.

Trial registration The protocol of the study was recorded in the Iranian Registry of Clinical Trials (IRCT20180712040438N3).

Circulating Spexin Is Associated with Body Mass Index and Fat Mass but Not with Physical Activity and Psychological Parameters in Women across a Broad Body Weight Spectrum

Spexin (SPX) is a novel, widely expressed peptide, with anorexigenic effects demonstrated in animal models and negatively correlated with body mass index (BMI) in humans. It increases locomotor activity in rodents and is elevated in human plasma following exercise. Studies have also shown an effect of stress and anxiety on SPX’s expression in different brain structures in animals. The relationships between plasma SPX and physical activity, body composition, and patient-reported outcomes such as perceived stress, depressiveness, anxiety, and eating behaviors are unknown and were examined in this study over a wide BMI range. A total of 219 female (n = 68 with anorexia nervosa; n = 79 with obesity; n = 72 with normal weight) inpatients were enrolled. Perceived stress (PSQ 20), anxiety (GAD 7), depressiveness (PHQ 9), and eating disorder pathology (EDI 2), as well as BMI, bioimpedance analysis, and accelerometry, were measured cross-sectionally at the beginning of treatment and correlated with plasma SPX levels (measured by ELISA) obtained at the same time. Plasma SPX levels were negatively associated with BMI (r = −0.149, p = 0.027) and body fat mass (r = −0.149, p = 0.04), but did not correlate with perceived stress, anxiety, depressiveness, eating behavior, energy expenditure, and physical activity (p > 0.05). The results replicate the negative correlation of SPX with BMI and fat mass, but do not support the hypothesis that peripheral SPX plays a role in the regulation of stress, depressiveness, anxiety, eating behavior, or physical activity.

Emerging central and peripheral actions of spexin in feeding behavior, leptin resistance and obesity

Consumption of a high calorie diet with irregular eating and sedentary behavior habits is typical of the current suboptimal lifestyle, contributing to the development of metabolic diseases such as obesity and type 2 diabetes mellitus. Most notably, the disorder of adipokine secretion in visceral adiposity is a major contributor to metabolic diseases with advancing age. In this regard, spexin and leptin are established as anorexigenic adipokines that can modulate adipogenesis and glucose metabolism by suppressing food intake or increasing energy expenditure, respectively. Emerging evidence points out that spexin levels are lower in the serum and adipose tissue of patients with obesity and/or insulin resistance, whereas circulating levels of leptin are higher in obesity and comorbidities. In turn, spexin and leptin pharmacologically induce beneficial effects on the brain's modulation of food intake and energy expenditure. On the other hand, endocrine crosstalk via spexin and leptin has also been reported in patients suffering from obesity and diabetes. Spexin plays a crucial role in the regulation of leptin secretion and leptin resistance. It should therefore be taken into account that studying the role of spexin in leptin regulation will help us combat the pathologies of obesity caused by leptin resistance.

Serum spexin levels are not associated with size at birth but are associated with metabolic syndrome components in prepubertal children born at term

BACKGROUND

Babies born small for gestational age (SGA) are at risk of obesity and metabolic syndrome (MetS). Spexin (SPX) is a novel peptide implicated in food intake and obesity. Spexin levels are lower in obese subjects. This study investigated the potential association of SPX and some obesity related peptides such as leptin and active ghrelin with size at birth and MetS components in prepubertal children born term and either SGA or appropriate for GA (AGA). Secondary aim was to identify whether any of the investigated peptides were associated with MetS components.

METHODS

We conducted a cross-sectional study of 37 consecutive (median age: 5.6 y) SGA- and 50 (median age: 5.9 y) AGA-born children. Clinical evaluations were performed using standard methods. Several biochemical variables (SPX, total leptin, and active ghrelin levels) were analyzed. Age-dependent cut-off values were used to define MetS components, including excess adiposity, hypertension, insulin resistance, and dyslipidemia. The associations between the assessed clinical and laboratory variables and MetS components were investigated.

RESULTS

Children born SGA had higher frequencies of MetS components than AGA-born peers (p < 0.01). None of the investigated peptides were different between children born SGA and AGA after correcting for body mass index (p > 0.05 for all). Serum SPX levels were lower in children with at least one metS component than those without MetS components (p = 0.018).

CONCLUSIONS

Size at birth had no association with serum SPX. Serum SPX levels are decreased in prepubertal children with MetS components.

Assessment of Serum Spexin Levels in Obese Adolescents with Metabolic Syndrome Antecedents: Preliminary Results

OBJECTIVE

Spexin (SPX) is a novel peptide implicated in food intake and satiety. SPX levels are reduced in obese patients.

AIM

This study aimed to compare serum SPX levels in obese adolescents versus healthy controls and to assess the associations of metabolic syndrome (metS) antecedents with serum SPX levels.

METHODS

Eighty consecutive obese adolescents aged 10-18 years and 80 healthy peers were enrolled. Anthropometric measurements, pubertal examinations, and clinical blood pressure measurements were performed. Fasting blood samples were drawn for glucose, insulin, lipids, uric acid, alanine aminotransferase (ALT), and SPX. metS was diagnosed using International Diabetes Federation criteria. Associations of serum SPX with clinical and laboratory variables were assessed.

RESULTS

Obese adolescents had lower serum SPX levels than healthy peers (50 pg/mL [25-75% IQR: 25-98 pg/mL] and 67.0 pg/mL [25-75% IQR: 32.5-126.0 pg/mL]; respectively, p = 0.035). Twenty (25%) obese adolescents were diagnosed as having metS. Obese adolescents with metS had lower SPX than those without metS (24.5 pg/mL [25-75% IQR: 15.3-49.5 pg/mL] and 69.0 pg/mL [25-75% IQR: 42.0-142.0 pg/mL]; respectively, p < 0.0001). The frequencies of hyperuricemia, IR, and elevated ALT were similar in obese adolescents with metS and those without metS (p > 0.05 for all). Serum uric acid levels were correlated significantly with serum SPX after correcting for BMI and HOMA-IR (r = -0.41, p < 0.05). A serum SPX level at a cutoff level of 49.5 pg/mL predicted the presence of metS in obese adolescents with 75% sensitivity and 71% specificity.

CONCLUSIONS

Obese adolescents have reduced SPX levels, and this reduction is more pronounced in those with metS. Further research is needed to verify the utility of SPX as a biomarker in the diagnosis of metS in obese adolescents.

Impact of spexin on metabolic diseases and inflammation: An updated minireview

Spexin (SPX) is a 14 amino acid length peptide hormone which was discovered using bioinformatic tools. It is extensively expressed in central and peripheral tissues and secreted into circulation in response to metabolic stress. Recent studies revealed that SPX acts as a multifunctional peptide in various metabolic processes such as body weight, food intake, energy balance, glucose and lipid metabolism, lipid storage, salt-water balance, and arterial blood pressure. Endogenous SPX is sensitive to metabolic changes, and circulating levels of SPX have been shown to be reduced in chronic diseases such as obesity, diabetes, and insulin resistance. Moreover, in fish and rodent models, systemic SPX treatment has positive effects on metabolism including reduced food intake, fat mass, lipid accumulation, and inflammation, improved insulin sensitivity, energy expenditure, and organ functions which are underlying mechanisms in diseases. Taken together, these findings suggest that SPX is a potential drug target for the development of new pharmacological strategies to cure metabolic diseases. This review focuses on metabolo-protective properties of SPX and discusses novel insights into the biology and mechanism of SPX in the pathogenesis of diabetes, obesity, non-alcoholic fatty liver disease, metabolic syndrome, polycystic ovary syndrome, cardiovascular diseases, and kidney diseases, which are considerable global health problems.

Fat-free/lean body mass in children with insulin resistance or metabolic syndrome: a systematic review and meta-analysis

BACKGROUND

Lean / Fat Free Body Mass (LBM) is metabolically involved in active processes such as resting energy expenditure, glucose uptake, and myokine secretion. Nonetheless, its association with insulin sensitivity / resistance / glucose tolerance and metabolic syndrome remains unclear in childhood.

METHODS

The current investigation aimed to examine the differences in fat-free mass /lean body mass according to the presence of insulin sensitivity/insulin resistance/glucose tolerance/metabolic syndrome in children. A systematic search was carried out in Medline/PubMed, Embase, Scopus, Web of Science, and SciELO, covering the period from each database's respective start to 21 June 2021. Two researchers evaluated 7111 studies according to the inclusion criteria: original human studies, written in English or Spanish, evaluating fat-free mass/lean body mass in children and adolescents including both with and without insulin sensitivity/insulin resistance /glucose tolerance and metabolic syndrome and reported the differences between them in terms of fat free mass/lean body mass. The results of the studies were combined with insulin sensitivity, insulin, resistance, glucose tolerance and metabolic syndrome. The standardized mean difference (SMD) in each study was calculated and combined using the random-effects model. Heterogeneity between studies was tested using the index of heterogeneity (I2), leave-one-out sensitivity analyses were performed, and publication bias was assessed using the Egger and Begg tests.

RESULTS

Finally, 15 studies which compared groups defined according to different glucose homeostasis criteria or metabolic syndrome out of 103 eligible studies were included in this systematic review and 12 studies in the meta-analysis. Meta-analysis showed lower fat-free mass/lean body mass percentage in participants with insulin resistance/glucose tolerance/metabolic syndrome (SMD -0.47; 95% CI, - 0.62 to - 0.32) while in mass units (kg), higher values were found in the same group (SMD, 1.01; 95% CI, 0.43 to 1.60).

CONCLUSIONS

Our results identified lower values of fat-free mass/lean body mass (%) in children and adolescents with insulin resistance/glucose tolerance/metabolic syndrome and higher values of fat-free mass/lean body mass when these are expressed in kg. The evidence of the impact of lean mass on children's glucose homeostasis or metabolic syndrome is limited, so future studies research should focus on explaining the effect of fat-free mass/lean body mass on different metabolic outcomes. Moreover, it may be interesting to evaluate the quality (muscle density) or functional (muscle strength) outcomes in addition to both absolute (kg) and relative (%) values in future studies. The systematic review was prospectively registered at PROSPERO (registration number CRD42019124734; available at: http://www.crd.york.ac.uk/prospero [accessed: 05 April 2019]).

Adipose tissue spexin in physical exercise and age-associated diseases

It is known that a strong association exists between a suboptimal lifestyle (physical inactivity and sedentary behavior and/or high calorie diet) and increased propensity of developing age-associated diseases, such as obesity and T2DM. Physical exercise can alleviate obesity-induced insulin resistance and T2DM, however, the precise mechanism for this outcome is not fully understood. The endocrine disorder of adipose tissue in obesity plays a critical role in the development of insulin resistance. In this regard, spexin has been recently described as an adipokine that plays an important role in the pathophysiology of obesity-induced insulin resistance and T2DM. In obese states, expression of adipose tissue spexin is reduced, inducing the adipose tissue and skeletal muscle more susceptible to insulin resistance. Emerging evidences point out that exercise can increase spexin expression. In return, spexin could exert the exercise-protective roles to ameliorate insulin resistance, suggesting that spexin is a potential mediator for exercise to ameliorate obesity-induced insulin resistance and T2DM, namely, the beneficial effect of exercise on insulin sensitivity is at least partly mediated by spexin. This review summarizes our and others' recent studies regarding the effects of obesity on adipose tissue spexin induction, along with the potential effect of exercise on this response in obese context, and provides a new insight into the multivariate relationship among exercise, spexin and T2DM. It should be therefore taken into account that a combination of spexin and exercise training is an effective therapeutic strategy for age-associated diseases.

Spexin: Its role, regulation, and therapeutic potential in the hypothalamus

Spexin is the most recently discovered member of the galanin/kisspeptin/spexin family of peptides. This 14-amino acid peptide is highly conserved and is implicated in homeostatic functions including, but not limited to, metabolism, energy homeostasis, and reproduction. Spexin is expressed by neurons in the hypothalamus, which coordinate energy homeostasis and reproduction. Critically, levels of spexin appear to be altered in disorders related to energy homeostasis and reproduction, such as obesity, diabetes, and polycystic ovarian syndrome. In this review, we discuss the evidence for the involvement of spexin in the hypothalamic control of energy homeostasis and reproduction. The anorexigenic properties of spexin have been attributed to its effects on the energy-regulating neuropeptide Y/agouti-related peptide neurons and proopiomelanocortin neurons. While the role of spexin in reproduction remains unclear, there is evidence that gonadotropin-releasing hormone expressing neurons may produce and respond to spexin. Furthermore, we discuss the disorders and concomitant treatments, which have been reported to alter spexin expression, as well as the underlying signaling mechanisms that may be involved. Finally, we discuss the biochemical basis of spexin, its interaction with its cognate receptors, and how this information can be adapted to develop therapeutics for disorders related to the alteration of energy homeostasis and reproduction.

Novel insights on the role of spexin as a biomarker of obesity and related cardiometabolic disease

Spexin (SPX) is a 14-amino acid neuropeptide, discovered recently using bioinformatic techniques. It is encoded by the Ch12:orf39 gene that is widely expressed in different body tissues/organs across species, and secreted into systemic circulation. Recent reports have highlighted a potentially important regulatory role of SPX in obesity and related comorbidities. SPX is also ubiquitously expressed in human tissues, including white adipose tissue. The circulating concentration of SPX is significantly lower in individuals with obesity compared to normal weight counterparts. SPX's role in obesity appears to be related to various factors, such as the regulation of energy expenditure, appetite, and eating behaviors, increasing locomotion, and inhibiting long-chain fatty acid uptake into adipocytes. Recent reports have also suggested SPX's relationship with novel biomarkers of cardiovascular disease (CVD) and glucose metabolism and evoked the potential role of SPX as a key biomarker/player in the early loss of cardiometabolic health and development of CVD and diabetes later in life. Data on age-related changes in SPX and SPX's response to various interventions are also emerging. The current review focuses on the role of SPX in obesity and related comorbidities across the life span, and its response to interventions in these conditions. It is expected that this article will provide new ideas for future research on SPX and its metabolic regulation, particularly related to cardiometabolic diseases.

The Role of Peptide Hormones Discovered in the 21st Century in the Regulation of Adipose Tissue Functions

Peptide hormones play a prominent role in controlling energy homeostasis and metabolism. They have been implicated in controlling appetite, the function of the gastrointestinal and cardiovascular systems, energy expenditure, and reproduction. Furthermore, there is growing evidence indicating that peptide hormones and their receptors contribute to energy homeostasis regulation by interacting with white and brown adipose tissue. In this article, we review and discuss the literature addressing the role of selected peptide hormones discovered in the 21st century (adropin, apelin, elabela, irisin, kisspeptin, MOTS-c, phoenixin, spexin, and neuropeptides B and W) in controlling white and brown adipogenesis. Furthermore, we elaborate how these hormones control adipose tissue functions in vitro and in vivo.

Mouse Spexin: (III) Differential Regulation by Glucose and Insulin in Glandular Stomach and Functional Implication in Feeding Control

Spexin (SPX), a neuropeptide with diverse functions, is a novel satiety factor in fish models and its role in feeding control has been recently confirmed in mammals. In mouse, food intake was shown to trigger SPX expression in glandular stomach with parallel rise in serum SPX and these SPX signals could inhibit feeding via central actions within the hypothalamus. However, the mechanisms for SPX regulation by food intake are still unclear. To examine the role of insulin signal caused by glucose uptake in SPX regulation, the mice were IP injected with glucose and insulin, respectively. In this case, serum SPX was elevated by glucose but not altered by insulin. Meanwhile, SPX transcript expression in the glandular stomach was up-regulated by glucose but the opposite was true for insulin treatment. Using in situ hybridization, the differential effects on SPX gene expression were located in the gastric mucosa of glandular stomach. Co-injection experiments also revealed that glucose stimulation on serum SPX and SPX mRNA expressed in glandular stomach could be blocked by insulin. In gastric mucosal cells prepared from glandular stomach, the opposite effects on SPX transcript expression by glucose and insulin could still be noted with similar blockade of the stimulatory effects of glucose by insulin. In this cell model, SPX gene expression induced by glucose was mediated by glucose uptake via GLUT, ATP synthesis by glycolysis/respiratory chain, and subsequent modulation of KATP channel activity, but the voltage-sensitive Ca2+ channels were not involved. The corresponding inhibition by insulin, however, was mediated by PI3K/Akt, MEK1/2/ERK1/2, and P38MAPK cascades coupled to insulin receptor but not IGF-1 receptor. Apparently, glucose uptake in mice can induce SPX expression in the glandular stomach through ATP synthesis via glucose metabolism and subsequent modification of KATP channel activity, which may contribute to SPX release into circulation to act as the satiety signal after food intake. The insulin rise caused by glucose uptake, presumably originated from the pancreas, may serve as a negative feedback to inhibit the SPX response by activating MAPK and PI3K/Akt pathways in the stomach.