Circulating alarin concentrations are high in patients with type 2 diabetes and increased by glucagon-like peptide-1 receptor agonist treatment: An Consort-compliant study

Androgenetic Alopecia and Metabolic Syndrome: Is Alarin a Missing Link?

BACKGROUND

The field of research into the probable link between androgenetic alopecia (AGA) and metabolic syndrome (MetS) is rapidly expanding. The exact underlying pathogenesis yet to be identified. Alarin, a galanin neuropeptide, found to be elevated in patients with metabolic syndrome and may represent a potential link between AGA and MetS.

OBJECTIVE

The aim of this study was to assess serum levels of alarin in patients with AGA and investigate its possible correlation, if any, with criteria of MetS in those patients.

METHODS

The study included 50 male patients with AGA and 30 healthy controls. Weight, height, waist circumference, and body mass index (BMI) were all measured. Systolic and diastolic blood pressure readings were recorded. Serum level of lipids, fasting blood glucose (FBG) and alarin were also assessed.

RESULTS

Anthropometric measures, serum lipids, FBG, and serum alarin were much higher in patients with AGA compared to controls (p<0.05). Forty-one patients with AGA (82%) met the criteria for diagnosis of MetS. Serum level of alarin was significantly higher in those patients and correlated positively with severity and duration of AGA.

CONCLUSION

Serum level of alarin might represent a potential link between AGA and MetS, opening the door for better understanding of the pathogenesis of both conditions and the possible association between them.

Tip 2 diyabetli hastalarda angiopoietin benzeri protein 8 (ANGPTL8) ve Alarin düzeylerinin karşılaştırmalı bir değerlendirmesi

Purpose: Type 2 Diabetes Mellitus (T2DM) is one of the most serious public health problems that affect millions of people worldwide. There are 537 million adults diagnosed with diabetes worldwide and approximately 90% of these adults have type 2 diabetes. The study examined angiopoietin-like protein 8 (ANGPTL8) and Alarin levels of the patients diagnosed with T2DM in comparison with each other and with the healthy control group. Materials and Methods: The study was conducted with a diabetes group consisting of 67 patients who were newly diagnosed with T2DM and who did not use any medication, and the control group consisting of 55 healthy people. ANGPTL8 and Alarin levels were measured using the ELISA (enzyme-linked immunosorbent assay) method. Results: We found a significant increase in alarin and ANGPTL8 levels in the diabetic group compared to the control group. Furthermore, a positive correlation between Alarin levels and ANGPTL8, triglyceride, and insulin levels was found in the patient group. In addition, while both adipokines were higher in males in the patient group, both adipokines levels were lower in males than females in the control group, and there was a significant difference in ANGPTL8 levels. Conclusion: High levels of ANGPTL8 and Alarin may facilitate the development of diabetes through the insulin resistance pathway. If this mechanism is more clearly elucidated, there may be a significant improvement in diabetic treatment projection.

The evolving roles of alarin in physiological and disease conditions, and its future potential clinical implications

Alarin is a member of the galanin family of neuropeptides that is widely expressed in the central nervous system and peripheral tissues in humans and rodents. It was initially isolated fifteen years ago in ganglionic cells of human neuroblastoma. Subsequently, it was demonstrated to be broadly distributed in the blood vessels, skin, eyes, peripheral and central nervous systems, thymus, gastrointestinal tract, and endocrine organs of different species. Alarin is a 25 amino acid neuropeptide derived from the alternative splicing of the GALP gene, missing exon 3. It is found to be involved in several physiological functions that include feeding behavior, energy homeostasis, glucose homeostasis, body temperature, and reproduction. It has also vasoactive, anti-inflammatory, anti-edema, and antimicrobial activities. However, the physiological effects of alarin have not been fully elucidated and the receptors that mediate these effects are not currently known. Unearthing the novel biological effects of alarin and its unidentified receptors will therefore be a task in future biomedical research. In addition, alarin is involved in various disease conditions, such as metabolic syndrome, obesity, insulin resistance, type 2 diabetes, diabetic retinopathy, hypertension, cardiac fibrosis, polycystic ovarian syndrome, and depression. Thus, alarin may serve as a promising tool for future pharmacological treatment and diagnosis. But further research is awaited to confirm whether alarin has a protective or pathological role in these diseases. This article provides a comprehensive review on the evolving implications of alarin in a variety of physiological and disease conditions, and its future perspectives.

Regulatory effects and potential therapeutic implications of alarin in depression, and arguments on its receptor

Alarin is a pleiotropic peptide involved in a multitude of putative biological activities, notably, it has a regulatory effect on depression-like behaviors. Although further elucidating research is needed, animal-based cumulative evidence has shown the antidepressant-like effects of alarin. In light of its regulatory role in depression, alarin could be used as a promising antidepressant in future treatment for depression. Nevertheless, the available information is still insufficient and the therapeutic relevance of alarin in depression is still of concern. Moreover, a plethora of studies have reported that the actions of alarin, including antidepressant activities, are mediated by a separate yet unidentified receptor, highlighting the need for more extensive research. This review focuses on the current understanding of the regulatory effects and future therapeutic relevance of alarin on depression, and the arguments on its receptors.

Alarin moderated myocardial hypertrophy via inhibiting cyclic adenosine monophosphate/protein kinase A signaling pathway to attenuate autophagy

Alarin could alleviate myocardial infarction-induced heart failure. The present study was to explore whether alarin could alleviate myocardial hypertrophy via inhibiting cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signaling pathway to attenuate autophagy. Myocardial hypertrophy was induced by angiotensin (Ang) II infusion in vivo in mice and by Ang II treatment of neonatal rat cardiomyocytes (NRCMs) in vitro. The Ang II-induced hypertrophy and fibrosis of the heart were alleviated after alarin administration in mice. The increased atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and beta-myosin heavy chain (β-MHC), and the decreased alpha-myosin heavy chain (α-MHC) induced by Ang II were reversed by alarin treatment in NRCMs. Alarin inhibited the increases of cAMP and PKA in NRCMs. Treatment with cAMP or overexpression of PKA blocked the attenuating effects of alarin on Ang II-induced hypertrophy in NRCMs. Alarin reduced the Ang II-induced increases of LC3, Beclin 1, autophagy-related gene (Atg)3 and Atg5 in NRCMs. The overexpression of cAMP and PKA reversed the alleviating effects of alarin on the increased autophagy induced by Ang II in NRCMs. These results indicated that alarin could moderate cardiac remodeling. Alarin improved myocardial hypertrophy via inhibiting the cAMP/PKA signaling pathway to attenuate autophagy.

Alarin alleviated cardiac fibrosis via attenuating oxidative stress in heart failure rats

The present study was to explore whether alarin could alleviate heart failure (HF) and attenuate cardia fibrosis via inhibiting oxidative stress. The fibrosis of cardiac fibroblasts (CFs) was induced by angiotensin (Ang) II. HF models were induced by ligation of the left anterior descending artery to cause ischemia myocardial infarction (MI) in Sprague–Dawley rats. Alarin (1.0 nM/kg/d) was administrated by intraperitoneal injection for 28 days. The decreases of left ventricular (LV) ejection fraction (EF), fractional shortening (FS), the maximum of the first differentiation of LV pressure (LV ± dp/dt_max) and LV systolic pressure (LVSP), and the increases of LV volume in systole (LVVS), LV volume in diastole (LVVD), LV end-systolic diameter (LVESD) and LV end-diastolic diameter (LVEDD) in MI rats were improved by alarin treatment. The increases in the expression levels of collagen I, collagen III, and transforming growth factor (TGF)-β were inhibited by alarin treatment in CFs and in the hearts of MI rats. The levels of NADPH oxidase (Nox) activity, superoxide anions and malondialdehyde (MDA) levels were increased, and the level of superoxide dismutase (SOD) activity was reduced in Ang II-treated CFs, which were reversed by alarin. Nox1 overexpression reversed the effects of alarin on attenuating the increases of collagen I, collagen III and TGF-β expression levels induced by Ang II in CFs. These results indicated that alarin improved HF and cardiac fibrosis via inhibiting oxidative stress in HF rats. Nox1 played important roles in the regulation of alarin effects on attenuating CFs fibrosis induced by Ang II.

Plasma Alarin Level and Its Influencing Factors in Obese Newly Diagnosed Type 2 Diabetes Patients

OBJECTIVE

To investigate the plasma alarin level in newly diagnosed obese type 2 diabetes mellitus (T2DM) and its correlation with glucose and lipid metabolism and insulin resistance.

METHODS

From October 2018 to June 2020, 239 newly diagnosed T2DM patients were collected. According to obesity, patients were divided into T2DM obese group (n=135) and T2DM non-obese group (n =104). Gender, age, body mass index (BMI), blood lipids, blood glucose, glycosylated hemoglobin A1c (HbA1c), fasting insulin (FINS), plasma alarin concentration, homeostasis model assessment for insulin resistance (HOMA-IR), homeostasis model assessment for β-cell function (HOMA-β) and other clinical data were collected and analyzed.

RESULTS

BMI, triacylglycerol (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), fasting blood glucose (FPG), HbA1c, FINS, plasma alarin levels and HOMA-IR in the control group, T2DM non-obese group and T2DM obese group increased sequentially, and high-density lipoprotein-cholesterol (HDL-L) and HOMA-β decreased sequentially (P<0.05). Correlation analysis results showed that plasma alarin levels in T2DM patients were positively correlated with waistline, BMI, TC, LDL-C, FPG, HbA1c, FINS and HOMA-IR (P<0.05), and negatively correlated with HDL-C and HOMA-β (P <0.05), and the correlation coefficient of T2DM obese group was significantly higher than that of T2DM non-obese group (P<0.05). Multiple linear stepwise regression analysis showed that BMI, FPG, HbA1c, HOMA-β, and HOMA-IR were independent factors related to plasma alarin levels in T2DM non-obese and T2DM obese patients, and the correlation coefficient of the T2DM obese group was significantly higher than that of the T2DM non-obese group (P <0.05).

CONCLUSION

Plasma alarin levels increase in newly diagnosed T2DM and obese T2DM patients, which are affected by TC, BMI, FPG, HbA1c, HOMA-β and HOMA-IR, and may be involved in development of T2DM.

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.