Serum Galanin Levels in Young Healthy Lean and Obese Non-Diabetic Men during an Oral Glucose Tolerance Test

Abstract

Galanin (GAL) is a neuropeptide involved in the homeostasis of energy metabolism. The objective of this study was to investigate the serum levels of GAL during an oral glucose tolerance test (OGTT) in lean and obese young men. This cross-sectional study included 30 obese non-diabetic young men (median 22 years; mean BMI 37 kg/m2) and 30 healthy lean men (median 23 years; mean BMI 22 kg/m2). Serum GAL was determined during OGTT. The results of this study include that serum GAL levels showed a reduction during OGTT compared with basal levels in the lean subjects group. Conversely, serum GAL levels increased significantly during OGTT in obese subjects. Serum GAL levels were also higher in obese non-diabetic men compared with lean subjects during fasting and in every period of the OGTT (p < 0.001). Serum GAL levels were positively correlated with BMI, total fat, visceral fat, HOMA–IR, total cholesterol, triglycerides and Leptin. A multiple regression analysis revealed that serum insulin levels at 30, 60 and 120 minutes during the OGTT is the most predictive variable for serum GAL levels (p < 0.001). In conclusion, serum GAL levels are significantly higher in the obese group compared with lean subjects during an OGTT.

Positive correlation of galanin with insulin resistance and triglyceride levels in obese children

“…In a study conducted by Meczekalski et al (27), significantly higher levels of serum galanin were observed in adult obese women compared to controls. In another study, serum galanin levels in nondiabetic adult obese male subjects were reported to be significantly higher at baseline and during the oral glucose tolerance test (OGTT) compared to healthy controls (20). The results of our study extend these finding by indicating that galanin levels are associated with obesity in children and adolescents as well.…”

“…In other studies in adults with impaired glucose tolerance, type 2 diabetes, and gestational diabetes mellitus, serum galanin levels were reported to be significantly higher compared to healthy controls and correlated positively with glucose levels (13,14). Moreover, Sandoval-Alzate et al (20) reported a positive correlation between serum galanin levels and HOMA-IR, BMI, and insulin levels at all OGTT time points and with glucose levels at 60-and 120-min time points of the OGTT in nondiabetic obese adults. Similarly, in the present study, serum galanin levels were significantly correlated with fasting glucose, fasting insulin, and HOMA-IR in obese subjects, which seems to be conflicting with the positive effect of galanin on glucose metabolism.…”

“…Additionally, in our study, serum galanin levels in obese subjects with insulin resistance were higher than in those without insulin resistance (1.27 vs. 0.95 ng/mL); however, statistical significance could not be determined due to a low number of subjects in subgroup analyses. Some studies have demonstrated that serum galanin levels are closely associated with increased fat consumption and serum TG levels (5,10,19,20,(36)(37)(38)(39). Significantly higher fat-rich food consumption was observed in mice after an injection of galanin into the paraventricular nucleus or in galanin transgenic mice that led to overexpression of galanin (10,37).…”

“…Moreover, a limited number of studies investigating galanin concentrations have been conducted in children with type 1 diabetes and epilepsy receiving valproate, and significantly higher concentrations of galanin than in healthy subjects were demonstrated (17,18). Some studies have indicated that the galanin neuropeptide contributes to the regulation of glucose and insulin homeostasis by increasing insulin sensitivity (5,6,15,19,20). To the best of our knowledge, no prior study has investigated the relationship between galanin levels and childhood obesity.…”

Transcriptomic analysis and plasma metabolomics in Aldh16a1 -null mice reveals a potential role of ALDH16A1 in renal function

“…Galanin (GAL), the neuropeptide product of Gal , exhibits diverse physiological functions, including energy homeostasis. High levels of endogenous GAL in transgenic mice has been associated with obesity, as well as lipid metabolism alterations [34]. In addition, decreased GAL expression is associated with decreased appetite and increased levels of leptin, in agreement with the lipid metabolism alterations that have been shown in other studies [35,36].…”