Serum Galanin Concentration is Increased in Subjects with Impaired Glucose Tolerance

Cardioprotective effects of neuropeptide galanin: Focusing on its roles against diabetic heart

Following an unprecedented rise in the number of the aged, the incidence of age-related diseases, such as diabetes and cardiovascular disease, is consequently increasing in the world. Type 2 diabetes mellitus (T2DM) is associated with excess cardiovascular morbidity and mortality. The diabetic heart is characterized by increased cardiomyocyte stiffness and fibrotic changes. Despite many factors resulting in cardiomyocyte injury and dysfunction in diabetes, insulin resistance is still a critical etiology of diabetic cardiomyopathy. Preclinical and clinical studies have revealed an intriguing role for galanin in the pathogenesis of insulin resistance and diabetic heart disease. A significant change in plasma galanin levels occurred in patients suffering from type 2 diabetes or cardiomyocyte injury. In turn, galanin may also distinctly mitigate hyperglycemia and insulin resistance in diabetes as well as increase glucose metabolism and mitochondrial biogenesis in cardiac muscle. Here, we critically review current data about the multivariate relationship among galanin, insulin resistance, and cardiac muscle to comprehensively evaluate the protective role of galanin and its receptors for the diabetic heart and to determine whether galanin receptor 2 agonists potentially represent a feasible way to treat diabetic cardiomyopathy in the future.

Time-restricted feeding prevents metabolic diseases through the regulation of galanin/GALR1 expression in the hypothalamus of mice

PURPOSE

Time-restricted feeding (TRF) reverses obesity and insulin resistance, yet the central mechanisms underlying its beneficial effects are not fully understood. Recent studies suggest a critical role of hypothalamic galanin and its receptors in the regulation of energy balance. It is yet unclear whether TRF could regulate the expression of galanin and its receptors in the hypothalamus of mice fed a high-fat diet.

METHODS

To test this effect, we subjected mice to either ad lib or TRF of a high-fat diet for 8 h per day. After 4 weeks, galanin and many neuropeptides associated with the function of metabolism were examined.

RESULTS

The present findings showed that mice under TRF consume equivalent calories from a high-fat diet as those with ad lib access, yet are protected against obesity and have improved glucose metabolism. Plasma galanin, orexin A, irisin and adropin levels were significantly reversed by TRF regimen. Besides, TRF regimen reversed the progression of metabolic disorders in mice by increasing GLUT4 and PGC-1α expression in skeletal muscles. Moreover, the levels of galanin and GALR1 expression were severely diminished in the hypothalamus of the TRF mice, whereas GALR2 was highly expressed.

CONCLUSIONS

TRF diminished galanin and GALR1 expression, and increased GALR2 expression in the hypothalamus of mice fed a high-fat diet. The current studies provide additional evidence that TRF is effective in improving HFD-induced hyperglycemia and insulin resistance in mice, and this effect could be associated with TRF-induced changes of the galanin systems in the hypothalamus.

LEVEL OF EVIDENCE

No level of evidence, animal studies.

Galanin and glypican-4 levels depending on metabolic and cardiovascular risk factors in patients with polycystic ovary syndrome

OBJECTIVE

Galanin is a neuropeptide which has effects not only on metabolic syndrome but also on reproduction. Glypican-4 is an adipokine associated with insulin sensitivity by interacting directly with the insulin receptor. This study evaluated serum concentrations of galanin and glypican-4 in relation with the hormonal profile as well as metabolic and cardiovascular risk factors in patients with and without polycystic ovary syndrome (PCOS).

METHODS

A total of 44 women with PCOS and 44 age-matched controls were eligible. Hirsutism scores, hormonal profile, metabolic and cardiovascular risk factors as well as galanin and glypican-4 levels were evaluated in each subject.

RESULTS

Women with PCOS exhibited lower levels of galanin (20.2 pg/mL versus 26.4 pg/mL, p = 0.002) and higher concentrations of glypican-4 (3.1 ng/mL versus 2.6 ng/mL, p < 0.001) than controls. Both adipokines were correlated positively with body mass index (BMI), insulin, triglyceride and Homeostasis Model Assessment (HOMA) index; glypican-4 also showed positive correlations with fasting blood glucose, free testosterone, modified Ferriman-Gallwey scores (p < 0.05). Multiple Linear Regression analyses showed that PCOS and BMI were the best predictors affecting galanin levels with a decreasing and increasing effect respectively; however BMI was the best predictor affecting glypican-4 levels with an increasing effect (p < 0.001).

CONCLUSION

Galanin levels were lower and glypican-4 levels were higher in women with PCOS than controls. Further studies are needed to determine whether these adipokines could be used as additional markers for insulin sensitivity and lipid profile and whether they might play a role in the pathogenesis of PCOS, in which metabolic cardiovascular risks are increased.

Emerging roles of kisspeptin/galanin in age-related metabolic disease

Age is a major risk factor for developing metabolic diseases such as obesity and diabetes. There is an unprecedented rise in obesity and type 2 diabetes in recent decades. A convincing majority of brain-gut peptides are associated with a higher risk to develop metabolic disorders, and may contribute to the pathophysiology of age-related metabolic diseases. Accumulating basic studies revealed an intriguing role of kisspeptin and galanin involved in the amelioration of insulin resistance in different ways. In patients suffered from obesity and diabetes a significant, sex-related changes in the plasma kisspeptin and galanin levels occurred. Kisspeptin is anorexigenic to prevent obesity, its level is negatively correlative with obesity and insulin resistance. While galanin is appetitive to stimulate food intake and body weight, its level is positively correlative with obesity, HOMA-IR and glucose/triglyceride concentration. In turn, kisspeptin and galanin also distinctly increase glucose uptake and utilization as well as energy expenditure. This article reviews recent evidence dealing with the role of kisspeptin and galanin in the pathophysiology of age-related metabolic diseases. It should be therefore taken into account that the targeted modulation of those peptidergic signaling may be potentially helpful in the future treatment of age-related metabolic diseases.

Neuropeptidergic Control of Feeding: Focus on the Galanin Family of Peptides

Obesity/overweight are important health problems due to metabolic complications. Dysregulation of peptides exerting orexigenic/anorexigenic effects must be investigated in-depth to understand the mechanisms involved in feeding behaviour. One of the most important and studied orexigenic peptides is galanin (GAL). The aim of this review is to update the mechanisms of action and physiological roles played by the GAL family of peptides (GAL, GAL-like peptide, GAL message-associated peptide, alarin) in the control of food intake and to review the involvement of these peptides in metabolic diseases and food intake disorders in experimental animal models and humans. The interaction between GAL and NPY in feeding and energy metabolism, the relationships between GAL and other substances involved in food intake mechanisms, the potential pharmacological strategies to treat food intake disorders and obesity and the possible clinical applications will be mentioned and discussed. Some research lines are suggested to be developed in the future, such as studies focused on GAL receptor/neuropeptide Y Y₁ receptor interactions in hypothalamic and extra-hypothalamic nuclei and sexual differences regarding the expression of GAL in feeding behaviour. It is also important to study the possible GAL resistance in obese individuals to better understand the molecular mechanisms by which GAL regulates insulin/glucose metabolism. GAL does not exert a pivotal role in weight regulation and food intake, but this role is crucial in fat intake and also exerts an important action by regulating the activity of other key compounds under conditions of stress/altered diet.

A promising biomarker of elevated galanin level in hypothalamus for osteoporosis risk in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) and osteoporosis are two major healthcare problems worldwide. T2DM is considered to be a risk factor for osteoporosis. Interestingly, several epidemiological studies suggest that bone abnormalities associated with diabetes may differ, at least in part, from those associated with senile or post-menopausal osteoporosis. The growing prevalence that patients with T2DM simultaneously suffer from osteoporosis, puts forward the importance to discuss the relationship between both diseases, as well as to investigate correlative agents to treat them. Emerging evidences demonstrate that neuropeptide galanin is involved in the pathogenesis of T2DM and osteoporosis. Galanin via activation of central GALR2 increases insulin sensitivity as well as bone density and mass in animal models. The disorder of galanin function plays major role in development of both diseases. Importantly, galanin signaling is indispensable for ΔFosB, an AP1 antagonist, to play the bone mass-accruing effects in the ventral hypothalamic neurons of diabetic models. This review summarizes our and other recent studies to provide a new insight into the multivariate relationship among galanin, T2DM and osteoporosis, highlighting the beneficial effect of galanin on the comorbid state of both diseases. These may help us better understanding the pathogenesis of osteoporosis and T2DM and provide useful clues for further inquiry if elevated galanin level may be taken as a biomarker for both conjoint diseases, and GALR2 agonist may be taken as a novel therapeutic strategy to treat both diseases concurrently.

Short-term changes and correlations of plasma spexin, kisspeptin, and galanin levels after laparoscopic sleeve gastrectomy

PURPOSE

To determine the circulating levels of spexin, kisspeptin, galanin, and the correlations between these peptides after laparoscopic sleeve gastrectomy (LSG).

METHODS

The plasma levels of the spexin, kisspeptin, and galanin and metabolic parameters (body mass index, weight loss, % excess weight loss, body fat, fasting glucose, HbA1C, and cholesterol levels) were measured (baseline, 1 month, and 3 months) and correlated in thirty adult individuals with obesity (22 female and 8 male) after LSG.

RESULTS

The body mass index (BMI), body fat, fasting glucose, total and low-density lipoprotein cholesterol decreased, while high-density lipoprotein cholesterol and % EWL (excess weight loss) increased at 3 months after surgery. The plasma spexin levels increased at 3 months, kisspeptin levels increased at 1 month and stabilized afterward, and galanin levels decreased at 3 months after LSG. Significant correlations were found between metabolic parameters with spexin, kisspeptin, and galanin. In addition, spexin and kisspeptin were negatively correlated with galanin, while spexin was positively correlated with kisspeptin.

CONCLUSIONS

The biochemical data reveal evidence that LSG causes an increase in the levels of spexin, and kisspeptin and a decrease in galanin levels. Our findings, therefore, suggest a possible interaction between these novel peptides, which have potential roles in obesity and glucose metabolism.

Management of an emergency tooth extraction in diabetic patients on the dental chair

BACKGROUND AND OBJECTIVE

Approximately 75% of diabetic patients in Saudi Arabia had poor glycaemic control. A high proportion of these patients will attend dental surgery clinics for treatment. Therefore, dentists should be well-prepared to control any complications they might arise on the dental chair during the dental procedures. Management of the associated risk factors is important to limit disease complications and improve the health of patients with diabetes.The objectives of this review were to determine the maximum acceptable level of blood glucose for tooth removal in diabetics, show a systematic technique for the management of patients with diabetes on the dental chair. By using PRISMA guidelines, analysis of the published articles and reports across the world is considered one of the most appropriate available methods to obtain strong evidence about the acceptable levels of blood glucose where teeth extraction can be done safely.

RESULTS

A total of 1080 studies were retrieved using the search strategy. After screening 185 titles, abstracts and 85 full-text articles, 36 studies were included. The outcome of this systematic review revealed that fasting blood glucose level of 240 mg/dl is a critical point for any dental treatment because the warning signs of diabetes start coming out. Maximum acceptable levels of blood glucose for removal of teeth in diabetics are 180 mg/dl (before meal) and 234 mg/dl (2 h after a meal). High blood glucose levels reduce the secretion of nitric oxide (powerful vasodilator) in the body which leads to poor circulation and slow-healing socket. Uncontrolled diabetics are at high risk of infection because of the high ketone levels in the blood.

CONCLUSION

Fasting blood glucose level of 180 mg/dl is a cut-off point for any selective dental extraction. However, Random blood glucose level of 234 mg/dl (13 mmol/l) is a cut-off point for an emergency tooth extraction. Tightly controlled diabetic patients (blood glucose level below 70 mg/dl) are susceptible to hypoglycemia.

Galanin peptide family regulation of glucose metabolism

Recent preclinical and clinical studies have indicated that the galanin peptide family may regulate glucose metabolism and alleviate insulin resistance, which diminishes the probability of type 2 diabetes mellitus. The galanin was discovered in 1983 as a gut-derived peptide hormone. Subsequently, galanin peptide family was found to exert a series of metabolic effects, including the regulation of gut motility, body weight and glucose metabolism. The galanin peptide family in modulating glucose metabolism received recently increasing recognition because pharmacological activiation of galanin signaling might be of therapeutic value to improve insuin resistance and type 2 diabetes mellitus. To date, however, few papers have summarized the role of the galanin peptide family in modulating glucose metabolism and insulin resistance. In this review we summarize the metabolic effect of galanin peptide family and highlight its glucoregulatory action and discuss the pharmacological value of galanin pathway activiation for the treatment of glucose intolerance and type 2 diabetes mellitus.

Validation of antibody-based tools for galanin research

Antibodies are an integral biomedical tool, not only for research but also as therapeutic agents. However, progress can only be made with sensitive and specific antibodies. The regulatory (neuro)peptide galanin and its three endogenous receptors (GAL_1-3-R) are widely distributed in the central and peripheral nervous systems, and in peripheral non-neuronal tissues. The galanin system has multiple biological functions, including feeding behavior, pain processing, nerve regeneration and inflammation, to name only a few. Galanin could serve as biomarker in these processes, and therefore its receptors are potential drug targets for various diseases. For that reason, it is of paramount interest to precisely measure galanin peptide levels in tissues and to determine the cellular and subcellular localization of galanin receptors. A plethora of antibodies and antibody-based tools, including radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) kits, are commercially available to detect galanin and its receptors. However, many of them lack rigorous validation which casts doubt on their specificity. A goal of the present study was to raise awareness of the importance of validation of antibodies and antibody-based tools, with a specific focus on the galanin system. To that end, we tested and report here about commercially available antibodies against galanin and galanin receptors that appear specific to us. Furthermore, we investigated the validity of commercially available galanin ELISA kits. As the tested ELISAs failed to meet the validation requirements, we developed and validated a specific sandwich ELISA which can be used to detect full-length galanin in human plasma.