Crosstalk of hypothalamic chemerin, histamine, and AMPK in diet-and olanzapine-induced obesity in rats

Tanycytes in the nexus of hypothalamic inflammation, appetite control, and obesity

Hypothalamic inflammation has been identified as a critical factor driving the development of obesity and associated metabolic disorders. This inflammation-related disruption of energy balance relies on alterations in metabolic cues sensing and hypothalamic cellular functions, together leading to overeating and weight gain. Within the hypothalamic cellular networks controlling energy balance, recent studies have highlighted the significance of glial dysfunction in these processes, suggesting that these cells could provide new avenues for weight loss therapies. Glia rapidly activates following the consumption of a high-fat diet, even after a very short exposure, and contributes to the disruption of the entire system through inflammatory crosstalk. This review explores recent progress in understanding the molecular interactions between glial cells and neurons in hypothalamic inflammation related to obesity, diabetes, and associated complications. Notably, it highlights specialized ependymal cells called tanycytes, whose role is still underestimated in hypothalamic inflammation, and examines the potential for targeting this cell type as a treatment strategy for metabolic disorders.

Adipokines level in plasma, hypothalamus, ovaries and adipose tissue of rats with polycystic ovary syndrome

RESEARCH QUESTION

Do the levels of adipokines (adiponectin, apelin, chemerin and vaspin) in plasma, hypothalamus, ovaries and periovarian adipose tissue differ during polycystic ovarian syndrome (PCOS)?

DESIGN

The PCOS was induced in rats by oral administration of non-steroidal aromatase inhibitor letrozole. To determine the plasma levels of adiponectin, apelin, chemerin and vaspin enzyme-linked immunosorbent assays were carried out. To assess the expression (gene and protein) and immunolocalization of these adipokines and their receptors, namely Adipor1 and Adipor2 for adiponectin, Aplnr for apelin, Ccrl2, Cmklr1 and Gpr1 for chemerin and Grp78 for vaspin in the hypothalamus, real-time polymerase chain reaction, and Western blot and immunohistochemistry were used to analyse ovaries and periovarian adipose tissue respectively.

RESULTS

In PCOS, the plasma level of adiponectin decreased (P = 0.0003), whereas apelin, chemerin and vaspin increased (P ≤ 0.0479). Moreover, PCOS modulates the expression of adipokines and their receptors in the hypothalamus, ovaries and periovarian adipose tissue compared with healthy rats (P ≤ 0.487).

CONCLUSIONS

A strong relationship was found between PCOS and adipokines, which suggests that adipokines may be a biomarker of PCOS.

Exploring the therapeutic potential of chlorogenic acid in alleviating olanzapine-induced metabolic syndrome in rats: a key role of hypothalamic satiety proteins

Objectives: Olanzapine (Olz) is an effective antipsychotic medication for schizophrenia; however, its use is associated with weight gain and metabolic disorders. Chlorogenic acid (CGA), a dietary polyphenol, has a promising potential for the treatment of obesity, diabetes, and hypertension. This study aimed to determine whether CGA could effectively manage Olz-induced metabolic syndrome (MetS) in a rat model, with metformin (Met) as a positive control.Methods: Female Wistar rats were divided into seven groups: control; Olz (5 mg/kg/day, IP); CGA (20, 40, and 80 mg/kg/day, gavage) plus Olz; Met (100 mg/kg/day, gavage) plus Olz; and CGA (80 mg/kg/day, gavage) for 30 days. Metabolic parameters including body weight, fasting blood glucose, triglycerides, and blood pressure were assessed. This study focused on evaluating serum levels of leptin and adiponectin, as well as hypothalamic protein expression of pro-opiomelanocortin (POMC), neuropeptide Y (NPY), AMP-activated protein kinase (AMPK), and 5-HT2C receptors (5-HT2CR), which are known to influence energy balance and potentially play a role in Olz-induced metabolic abnormalities.Results: Olz caused substantial hyperphagia, weight gain, hypertension, and liver damage, along with elevated fasting blood glucose, triglycerides, and leptin levels. CGA and Met mitigated these effects, although Olz-induced elevation of adiponectin levels remained unaffected by either treatment. Mechanistically, Olz reduced 5-HT2CR protein levels, a trend that was observed in the CGA and Met therapy groups. Olz also enhanced NPY protein levels and the pAMPK/AMPK ratio while lowering POMC protein levels. These alterations were reversed in rats administered CGA or Met.Discussion: These findings suggest that CGA effectively attenuated the adverse metabolic consequences of Olz by modulating leptin, NPY, POMC, and AMPK protein levels. CGA's therapeutic potential highlights its potential as a dietary intervention for managing antipsychotic-induced metabolic disturbances.

Targeting histamine in metabolic syndrome: Insights and therapeutic potential

Metabolic syndrome is a complex disorder defined by a cluster of interconnected factors including obesity, insulin resistance, hypertension, hyperlipidemia and hyperglycemia which increase the risk of cardiovascular disease, non-alcoholic fatty liver disease, type 2 diabetes mellitus and other related diseases. Histamine, as a biogenic amine, participates in various physiological processes. Increasing evidence suggests histamine plays critical roles in Metabolic syndrome as well as its associated diseases by interacting with four histamine receptors. In this review, we summarize the functions and mechanisms of histamine in Metabolic syndrome, indicating histamine as a possible target in treating Metabolic syndrome and its associated diseases.

Saturated fatty acids stimulate cytokine production in tanycytes via the PP2Ac-dependent signaling pathway

The hypothalamic tanycytes are crucial for free fatty acids (FFAs) detection, storage, and transport within the central nervous system. They have been shown to effectively respond to fluctuations in circulating FFAs, thereby regulating energy homeostasis. However, the precise molecular mechanisms by which tanycytes modulate lipid utilization remain unclear. Here, we report that the catalytic subunit of protein phosphatase 2 A (PP2Ac), a serine/threonine phosphatase, is expressed in tanycytes and its accumulation and activation occur in response to high-fat diet consumption. In vitro, tanycytic PP2Ac responds to palmitic acid (PA) exposure and accumulates and is activated at an early stage in an AMPK-dependent manner. Furthermore, activated PP2Ac boosts hypoxia-inducible factor-1α (HIF-1α) accumulation, resulting in upregulation of an array of cytokines. Pretreatment with a PP2Ac inhibitor, LB100, prevented the PA-induced elevation of vascular endothelial growth factor (VEGF), fibroblast growth factor 1 (FGF1), hepatocyte growth factor (HGF), and dipeptidyl peptidase IV (DPPIV or CD26). Our results disclose a mechanism of lipid metabolism in tanycytes that involves the activation of PP2Ac and highlight the physiological significance of PP2Ac in hypothalamic tanycytes in response to overnutrition and efficacious treatment of obesity.

The role of the gut microbiome in weight-gain in schizophrenia patients treated with atypical antipsychotics: Evidence based on altered composition and function in a cross-sectional study

OBJECTIVES

We aimed to explore the interconnection between the weight-gain in schizophrenia patients with atypical antipsychotic treatment and gut microbiome.

METHODS

This study employed a cross-sectional design, encompassing a total of 88 schizophrenia patients with long-term atypical antipsychotic treatment. The 16S rRNA gene sequencing was used to identify gut microbiome contents.

RESULTS

No significant differences in alpha diversity between normal-weight and overweight schizophrenia treated with atypical antipsychotics. The beta diversity analysis showed that overweight patients clustered tightly while normal-weight patients clustered widely. For taxonomic composition, overweight patients had a lower relative abundance in Porphyromonadaceae at family level and Butyrivibrio at genus level, but higher relative abundance in Ruminococcus2 and Clostridium_XIVa at genus level than normal-weight patients. Function prediction revelated that four pathways (including Cell cycle, Non-homologous end-joining, Vibrio cholerae infection and Meiosis-yeast) were significantly different between groups. Correlation analysis indicated that Klebsiella, Butyrivibrio, Unassigned, Methanosphaera, Holdemania, Anaerotruncus were negatively, while Veillonella was positively correlated with BMI in patients.

CONCLUSION

Our findings offer evidence that perturbations in the gut microbiome composition, encompassing taxa such as Porphyromonadaceae, Butyrivibrio, Ruminococcus2, and Clostridium_XIVa, in conjunction with distinct functional pathways including Cell cycle, Non-homologous end-joining, Vibrio cholerae infection, and Meiosis-yeast, might contribute to the weight-gain in schizophrenia treated with atypical antipsychotics.

Pharmacological and physiological roles of adipokines and myokines in metabolic-related dementia

Dementia is a detrimental neuropathologic condition with considerable physical, mental, social, and financial impact on patients and society. Patients with metabolic syndrome (MetS), a group of diseases that occur in tandem and increase the risk of neurologic diseases, have a higher risk of dementia. The ratio between muscle and adipose tissue is crucial in MetS, as these contain many hormones, including myokines and adipokines, which are involved in crosstalk and local paracrine/autocrine interactions. Evidence suggests that abnormal adipokine and myokine synthesis and release may be implicated in various MetS, such as atherosclerosis, diabetic mellitus (DM), and dyslipidemia, but their precise role is unclear. Here we review the literature on adipokine and myokine involvement in MetS-induced dementia via glucose and insulin homeostasis regulation, neuroinflammation, vascular dysfunction, emotional changes, and cognitive function.

Tanycyte, the neuron whisperer

Reciprocal communication between neurons and glia is essential for normal brain functioning and adequate physiological functions, including energy balance. In vertebrates, the homeostatic process that adjusts food intake and energy expenditure in line with physiological requirements is tightly controlled by numerous neural cell types located within the hypothalamus and the brainstem and organized in complex networks. Within these neural networks, peculiar ependymoglial cells called tanycytes are nowadays recognized as multifunctional players in the physiological mechanisms of appetite control, partly by modulating orexigenic and anorexigenic neurons. Here, we review recent advances in tanycytes' impact on hypothalamic neuronal activity, emphasizing on arcuate neurons.

Blood and Urinary Biomarkers of Antipsychotic-Induced Metabolic Syndrome

Metabolic syndrome (MetS) is a clustering of at least three of the following five medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Antipsychotic (AP)-induced MetS (AIMetS) is the most common adverse drug reaction (ADR) of psychiatric pharmacotherapy. Herein, we review the results of studies of blood (serum and plasma) and urinary biomarkers as predictors of AIMetS in patients with schizophrenia (Sch). We reviewed 1440 studies examining 38 blood and 19 urinary metabolic biomarkers, including urinary indicators involved in the development of AIMetS. Among the results, only positive associations were revealed. However, at present, it should be recognized that there is no consensus on the role of any particular urinary biomarker of AIMetS. Evaluation of urinary biomarkers of the development of MetS and AIMetS, as one of the most common concomitant pathological conditions in the treatment of patients with psychiatric disorders, may provide a key to the development of strategies for personalized prevention and treatment of the condition, which is considered a complication of AP therapy for Sch in clinical practice.

Metabolic Syndrome: Lessons from Rodent and Drosophila Models

Overweight and obesity are health conditions tightly related to a number of metabolic complications collectively called “metabolic syndrome” (MetS). Clinical diagnosis of MetS includes the presence of the increased waist circumference or so-called abdominal obesity, reduced high density lipoprotein level, elevated blood pressure, and increased blood glucose and triacylglyceride levels. Different approaches, including diet-induced and genetically induced animal models, have been developed to study MetS pathogenesis and underlying mechanisms. Studies of metabolic disturbances in the fruit fly Drosophila and mammalian models along with humans have demonstrated that fruit flies and small mammalian models like rats and mice have many similarities with humans in basic metabolic functions and share many molecular mechanisms which regulate these metabolic processes. In this paper, we describe diet-induced, chemically and genetically induced animal models of the MetS. The advantages and limitations of rodent and Drosophila models of MetS and obesity are also analyzed.

Brexpiprazole Reduces 5-HT7 Receptor Function on Astroglial Transmission Systems

Several atypical antipsychotics exert mood-stabilising effects via the modulation of various monoamine receptors and intracellular signallings. Recent pharmacodynamic studies suggested that tripartite synaptic transmission can contribute to the pathophysiology of schizophrenia and mood disorders, their associated cognitive impairment, and several adverse reactions to atypical antipsychotics. Therefore, to explore the mechanisms underlying the antidepressive mood-stabilising and antipsychotic effects of brexpiprazole (Brex), we determined the effects of subchronic administration of therapeutically relevant concentrations/doses of Brex on the protein expression of 5-HT receptors, connexin43, cAMP levels, and intracellular signalling in cultured astrocytes and rat hypothalamus using ultra-high-pressure liquid chromatography with mass spectrometry and capillary immunoblotting systems. Subchronic administration of a therapeutically relevant concentration of Brex (300 nM) downregulated both 5-HT1A (5-HT1AR) and 5-HT7 (5-HT7R) receptors, in addition to phosphorylated Erk (pErk), without affecting phosphorylated Akt in the astroglial plasma membrane. Subchronic administration of 300 nM Brex decreased and increased phosphorylated AMPK and connexin43, respectively, in the astroglial cytosol fraction. A therapeutically relevant concentration of Brex acutely decreased the astroglial cAMP level, whereas, under the inhibition of 5-HT1AR, Brex did not affect astroglial cAMP levels. However, the 5-HT7R-agonist-induced increased astroglial cAMP level was inhibited by Brex. In contrast to the in vitro study, systemic subchronic administration of effective doses of Brex (3 and 10 mg/kg/day for 14 days) increased the cAMP level but did not affect phosphorylated AMPK in the rat hypothalamus. These results suggest several complicated pharmacological features of Brex. Partial 5-HT1AR agonistic action predominates in the low range of therapeutically relevant concentrations of Brex, whereas in the high range, 5-HT7R inverse agonist-like action is overlapped on the 5-HT1A agonistic action. These unique suppressive effects of Brex on 5-HT7R play important roles in the clinical features of Brex regarding its antidepressive mood-stabilising actions.