Ectopic fat accumulation in human astrocytes impairs insulin action

Bridging metabolic syndrome and cognitive dysfunction: role of astrocytes

Metabolic syndrome (MetS) and cognitive dysfunction pose significant challenges to global health and the economy. Systemic inflammation, endocrine disruption, and autoregulatory impairment drive neurodegeneration and microcirculatory damage in MetS. Due to their unique anatomy and function, astrocytes sense and integrate multiple metabolic signals, including peripheral endocrine hormones and nutrients. Astrocytes and synapses engage in a complex dialogue of energetic and immunological interactions. Astrocytes act as a bridge between MetS and cognitive dysfunction, undergoing diverse activation in response to metabolic dysfunction. This article summarizes the alterations in astrocyte phenotypic characteristics across multiple pathological factors in MetS. It also discusses the clinical value of astrocytes as a critical pathologic diagnostic marker and potential therapeutic target for MetS-associated cognitive dysfunction.

Assessment of Changes in Body Composition After 3 Months of Dulaglutide Treatment

Background

Changes in body composition accompanied by glucagon-like peptide 1 receptor agonist (GLP-1RA) induced weight loss have drawn much attention. However, fewer studies have reported body composition changes in patients receiving dulaglutide therapy in Chinese population.

Methods

A total of 70 overweight/obese type 2 diabetes mellitus (T2DM) patients who received dulaglutide therapy were included. Clinical data were collected. Visceral fat area (VFA) and body composition were also measured. Changes in clinical indicators and body composition of patients before and after intervention were also analyzed. Correlation analysis and multiple linear regression model were used to evaluate the association between hemoglobin A1C (HbA1c) and body composition.

Results

The results showed that body weight (BW), VFA, body fat (BF), lean body mass (LBM), skeletal muscle mass (SMM) and water content were reduced after 3 months dulaglutide intervention. The lean body mass percentage (LBMP) and skeletal muscle mass percentage (SMMP) significantly increased. Moreover, there was no significant difference in bone mineral quality (BMQ) after the intervention. The multiple linear regression model revealed that the % change in BF was independently associated with % change in HbA1c (β = 0.449, t = 3.148, p=0.002).

Conclusion

These results indicate that dulaglutide intervention does not cause muscle and bone mass loss while inducing weight loss, and % change in BF was independently associated with improved glucose control during dulaglutide therapy. This study offers some positive results to support the clinical application of dulaglutide.

Profiling and Cellular Analyses of Obesity-Related circRNAs in Neurons and Glia under Obesity-like In Vitro Conditions

Recent evidence indicates that the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease, is associated with metabolic disorders such as diabetes and obesity. Various circular RNAs (circRNAs) have been found in brain tissues and recent studies have suggested that circRNAs are related to neuropathological mechanisms in the brain. However, there is a lack of interest in the involvement of circRNAs in metabolic imbalance-related neuropathological problems until now. Herein we profiled and analyzed diverse circRNAs in mouse brain cell lines (Neuro-2A neurons, BV-2 microglia, and C8-D1a astrocytes) exposed to obesity-related in vitro conditions (high glucose, high insulin, and high levels of tumor necrosis factor-alpha, interleukin 6, palmitic acid, linoleic acid, and cholesterol). We observed that various circRNAs were differentially expressed according to cell types with many of these circRNAs conserved in humans. After suppressing the expression of these circRNAs using siRNAs, we observed that these circRNAs regulate genes related to inflammatory responses, formation of synaptic vesicles, synaptic density, and fatty acid oxidation in neurons; scavenger receptors in microglia; and fatty acid signaling, inflammatory signaling cyto that may play important roles in metabolic disorders associated with neurodegenerative diseases.

Facilitation of Insulin Effects by Ranolazine in Astrocytes in Primary Culture

Ranolazine (Rn) is a drug used to treat persistent chronic coronary ischemia. It has also been shown to have therapeutic benefits on the central nervous system and an anti-diabetic effect by lowering blood glucose levels; however, no effects of Rn on cellular sensitivity to insulin (Ins) have been demonstrated yet. The present study aimed to investigate the permissive effects of Rn on the actions of Ins in astrocytes in primary culture. Ins (10−8 M), Rn (10−6 M), and Ins + Rn (10−8 M and 10−6 M, respectively) were added to astrocytes for 24 h. In comparison to control cells, Rn and/or Ins caused modifications in cell viability and proliferation. Rn increased protein expression of Cu/Zn-SOD and the pro-inflammatory protein COX-2 was upregulated by Ins. On the contrary, no significant changes were found in the protein expression of NF-κB and IκB. The presence of Rn produced an increase in p-ERK protein and a significant decrease in COX-2 protein expression. Furthermore, Rn significantly increased the effects of Ins on the expression of p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ. In addition, Rn + Ins produced a significant decrease in COX-2 expression. In conclusion, Rn facilitated the effects of insulin on the p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ signaling pathways, as well as on the anti-inflammatory and antioxidant effects of the hormone.

Hypothalamic Astrocytes as a Specialized and Responsive Cell Population in Obesity

Astrocytes are a type of glial cell anatomically and functionally integrated into the neuronal regulatory circuits for the neuroendocrine control of metabolism. Being functional integral compounds of synapses, astrocytes are actively involved in the physiological regulatory aspects of metabolic control, but also in the pathological processes that link neuronal dysfunction and obesity. Between brain areas, the hypothalamus harbors specialized functional circuits that seem selectively vulnerable to metabolic damage, undergoing early cellular rearrangements which are thought to be at the core of the pathogenesis of diet-induced obesity. Such changes in the hypothalamic brain region consist of a rise in proinflammatory cytokines, the presence of a reactive phenotype in astrocytes and microglia, alterations in the cytoarchitecture and synaptology of hypothalamic circuits, and angiogenesis, a phenomenon that cannot be found elsewhere in the brain. Increasing evidence points to the direct involvement of hypothalamic astrocytes in such early metabolic disturbances, thus moving the study of these glial cells to the forefront of obesity research. Here we provide a comprehensive review of the most relevant findings of molecular and pathophysiological mechanisms by which hypothalamic astrocytes might be involved in the pathogenesis of obesity.

Impact of different stereoisomers of inositol on insulin sensitivity of gestational diabetes mellitus patients

BACKGROUND

Inositol is a hexa-carbon polyol, a naturally soluble vitamin, often found in various foods.

AIM

To discuss the impact of different stereoisomers of inositol on insulin sensitivity of gestational diabetes mellitus (GDM) patients.

METHODS

Eighty GDM pregnant women were divided into four groups according to their treatment received: A group (placebo folic acid 400 μg/d), B group [myo-inositol (MI) 1500 mg, twice a day], C group [D-chiro-inositol (DCI) 250 mg, twice a day], and D group (inositol MI and inositol DCI 1500 mg/250 mg, twice a day). Each patient routinely used dietary guidance adjustments and did some safe and effective aerobic exercise in addition to receiving placebo or inositol from GDM diagnosis to delivery. Triglyceride, total cholesterol, fasting plasma glucose, oral glucose tolerance test postprandial glucose (2 h postprandial blood glucose), fasting insulin, fasting plasma glucose, and glycosylated hemoglobin levels and Homeostasis Model Assessment-insulin resistance (HOMA-IR) and Homeostasis Model Assessment-insulin sensitivity index (HOMA-ISI) scores were determined before treatment and 8 wk after treatment onset. Adverse maternal and infant outcomes, including hypoglycemia, excessive amniotic fluid, premature infants, macrosomia, fetal distress etc., were also recorded.

RESULTS

There was no statistical difference in the baseline data of each group. The levels of 2 h blood glucose, glycosylated hemoglobin, fasting insulin, total cholesterol, and triglyceride in the B, C, and D groups were significantly lower than those in the control group (A group) after treatment (P < 0.05). Moreover, compared with the B group, the level of the above indexes in the C and D groups decreased more significantly, and the differences were statistically significant (P < 0.05). The HOMA-IR of B, C, and D groups decreased significantly, and the HOMA-ISI increased significantly compared with the A group, and the differences were statistically significant (P < 0.05), among which the decrease of HOMA-IR and the increase of HOMA-ISI were more significant in the C and D group compared with the B group (P < 0.05). The occurrence rate of adverse maternal and infant outcomes in the C and D group was significantly lower than that in the control group (A group), and the differences were statistically significant (P < 0.05).

CONCLUSION

Treatment with different inositol stereoisomers (inositol MI and inositol DCI) can improve insulin sensitivity and reduce insulin resistance in diabetic patients, and inositol DCI has a better curative effect than inositol MI.