Involvement of TRPV1 Channels in Energy Homeostasis

TRPV1: A novel target for the therapy of diabetes and diabetic complications

BACKGROUND

Diabetes mellitus is a chronic metabolic disease characterized by abnormally elevated blood glucose levels. Type II diabetes accounts for approximately 90% of all cases. Several drugs are available for hyperglycemia treatment. However, the current therapies for managing high blood glucose do not prevent or reverse the disease progression, which may result in complications and adverse effects, including diabetic neuropathy, retinopathy, and nephropathy. Hence, developing safer and more effective methods for lowering blood glucose levels is imperative. Transient receptor potential vanilloid-1 (TRPV1) is a significant member of the transient receptor potential family. It is present in numerous body tissues and organs and performs vital physiological functions.

PURPOSE

This review aimed to develop new targeted TRPV1 hypoglycemic drugs by systematically summarizing the mechanism of action of the TRPV1-based signaling pathway in preventing and treating diabetes and its complications.

METHODS

Literature searches were performed in the PubMed, Web of Science, Google Scholar, Medline, and Scopus databases for 10 years from 2013 to 2023. The search terms included "diabetes," "TRPV1," "diabetic complications," and "capsaicin."

RESULTS

TRPV1 is an essential potential target for treating diabetes mellitus and its complications. It reduces hepatic glucose production and food intake and promotes thermogenesis, metabolism, and insulin secretion. Activation of TRPV1 ameliorates diabetic nephropathy, retinopathy, myocardial infarction, vascular endothelial dysfunction, gastroparesis, and bladder dysfunction. Suppression of TRPV1 improves diabetes-related osteoporosis. However, the therapeutic effects of activating or suppressing TRPV1 may vary when treating diabetic neuropathy and periodontitis.

CONCLUSION

This review demonstrates that TRPV1 is a potential therapeutic target for diabetes and its complications. Additionally, it provides a theoretical basis for developing new hypoglycemic drugs that target TRPV1.

Inulin may prevent the high-fat diet induced-obesity via suppressing endocannabinoid system in the prefrontal cortex in Wistar rats

High-fat diets contribute to various metabolic disorders. Inulin supplementation has been shown to reduce appetite, lower food intake, and promote weight loss. Although there is evidence that the endocannabinoid system has metabolic effects in the prefrontal cortex, studies investigating the effects of inulin on the endocannabinoid system are limited. This study investigated the impact of inulin on obesity through the endocannabinoid system in the prefrontal cortex. Twenty-four male Wistar rats were fed one of four diets over 12 weeks. Findings indicated that a high-fat diet led to obesity, whereas inulin reduced food intake and supported weight loss. Consequently, inulin supplementation both prevented obesity and significantly decreased the expressions of Adrb3 and Adcy1, and anandamide and 2-arachidonylglycerol levels in the prefrontal cortex. Additionally, inulin lowered leptin in circulation and stimulated Trpv1. Thus, inulin may mitigate obesity development, possibly by modulating gene expressions linked to obesity in the prefrontal cortex via endocannabinoids.

Transcriptomic Analysis of the Protective Effect of Piperine on Orlistat Hepatotoxicity in Obese Male Wistar Rats

Obesity is a risk factor for the development of noncommunicable diseases that impair the quality of life. Orlistat is one of the most widely used drugs in the management of obesity due to its accessibility and low cost. However, cases of hepatotoxicity have been reported due to the consumption of this drug. On the other hand, piperine is an alkaloid found in black pepper that has demonstrated antiobesity, antihyperlipidemic, antioxidant, prebiotic, and hepatoprotective effects. The aim of this study was to evaluate the protective effect of piperine on the toxicity of orlistat in liver tissue. Obese male rats were administered piperine (30 mg/kg), orlistat (60 mg/kg), and the orlistat-piperine combination (30 mg/kg + 60 mg/kg) daily for 6 weeks. It was observed that the orlistat-piperine treatment resulted in greater weight loss, decreased biochemical markers (lipid profile, liver enzymes, pancreatic lipase activity), and histopathological analysis showed decreased hepatic steatosis and reduction of duodenal inflammation. Transcriptomic analysis revealed that the administration of piperine with orlistat increased the expression of genes related to the beta-oxidation of fatty acids, carbohydrate metabolism, detoxification of xenobiotics, and response to oxidative stress. Therefore, the results suggest that the administration of orlistat-piperine activates signaling pathways that confer a hepatoprotective effect, reducing the toxic impact of this drug.

Fatty acid composition, lipid profile and oxidative stability of meat of broiler chickens fed diet containing bird eye pepper of varying inclusion level and sieve size

Nutritional modifications to improve meat quality is targeted by farmers. Bird eye pepper (BEP) contains bio-compounds of physiological significance. The potency of BEP of varying inclusion level and sieve size on meat quality [fatty acid (FA), lipid profile and oxidative stability] of broiler chickens was investigated. A total of 246 birds fed diet-containing BEP [inclusion level (0, 0.15 and 0.3%), sieve size (0.05 and 0.1 mm)] were randomized to six treatments replicated 4 times in a 2 by 3 factorial layout. After feeding (31 days), forty-eight birds (two per replicate) were slaughtered and breast muscles harvested. Meat lipid profile and 2-thiobarbituric acid reactive substance (TBARs) were determined on day (d) 0, while TBARs was further assessed on d 3 and 5, but FA on d 10 of refrigeration storage. BEP diet (0.15%) increased (p < 0.05) total monounsaturated FA (MUFA), unsaturated FA (UFA) and n-3 FA, while 0.05 mm BEP lowered (p < 0.05) meat index of thrombogenicity (TI) but increased meat hypocholesteromic: hypercholesteromic (HH) value. Dietary 0.15% (0.05 mm) BEP yielded low (p < 0.05) SFA but high MUFA: SFA, UFA: SFA and NVI, while 0.15% (0.1 mm) BEP diet resulted in high total MUFA and higher (p < 0.05) UFA, n-3 and n-3: n-6 FA. Control, 0.15% and 0.05 mm BEP diets reduced (p < 0.05) meat cholesterol value. This study has shown that 0.15% (0.05 mm) BEP diet had no deleterious effect on the growth of broiler chickens but improved the NVI, IA, TI, HH, TBARs and cholesterol of the meat - a significance to health-conscious consumers.

TRPV1 channel in the pathophysiology of epilepsy and its potential as a molecular target for the development of new antiseizure drug candidates

Identification of transient receptor potential cation channel, subfamily V member 1 (TRPV1), also known as capsaicin receptor, in 1997 was a milestone achievement in the research on temperature sensation and pain signalling. Very soon after it became evident that TRPV1 is implicated in a wide array of physiological processes in different peripheral tissues, as well as in the central nervous system, and thereby could be involved in the pathophysiology of numerous diseases. Increasing evidence suggests that modulation of TRPV1 may also affect seizure susceptibility and epilepsy. This channel is localized in brain regions associated with seizures and epilepsy, and its overexpression was found both in animal models of seizures and in brain samples from epileptic patients. Moreover, modulation of TRPV1 on non-neuronal cells (microglia, astrocytes, and/or peripheral immune cells) may have an impact on the neuroinflammatory processes that play a role in epilepsy and epileptogenesis. In this paper, we provide a comprehensive and critical overview of currently available data on TRPV1 as a possible molecular target for epilepsy management, trying to identify research gaps and future directions. Overall, several converging lines of evidence implicate TRPV1 channel as a potentially attractive target in epilepsy research but more studies are needed to exploit the possible role of TRPV1 in seizures/epilepsy and to evaluate the value of TRPV1 ligands as candidates for new antiseizure drugs.

Embryo thermal manipulation enhances mitochondrial function in the skeletal muscle of heat-stressed broilers by regulating transient receptor potential V2 expression

Heat stress induces mitochondrial dysfunction, thereby impeding skeletal muscle development and significantly impacting the economic efficiency of poultry production. This study aimed to investigate the effects of embryo thermal manipulation (TM, 41.5°C, 65% RH, 3 h/d during 16-18th embryonic age) on the mitochondrial function of the pectoralis major (PM) in broiler chickens exposed to thermoneutral (24 ± 1°C, 60% RH) or cyclic heat stress (35 ± 1°C, 60% RH, 12 h/d) from day 22 to 28, and to explore potential mechanisms involving transient receptor potential V2 (TRPV2). Additionally, in vitro experiments were conducted to assess the regulatory effects of TRPV2 pharmacological activation and inhibition on mitochondrial function in primary myotubes. The results revealed that TM had no discernible effect on the body weight and feed intake of broiler chickens under heat stress conditions (P > 0.05). However, it did delay the increase in rectal temperature and accelerate the decrease in serum T3 levels (P < 0.05). Furthermore, TM promoted the development of PM muscle fibers, significantly increasing myofiber diameter and cross-sectional area (P < 0.05). Under heat stress conditions, TM significantly upregulated the expression of mitochondrial electron transport chain (ETC) genes and TRPV2 in broiler PM muscle (P < 0.05), with a clear positive correlation observed between the two (P < 0.05). In vitro, pharmacological activation of TRPV2 not only increased its own expression but also enhanced mitochondrial ETC genes expression and oxidative phosphorylation function by upregulating intracellular calcium ion levels (P < 0.05). Conversely, TRPV2 inhibition had the opposite effect. Overall, this study underscores the potential of prenatal thermal manipulation in regulating postnatal broiler skeletal muscle development and mitochondrial function through the modulation of TRPV2 expression.

Implication of the endocannabidiome and metabolic pathways in fragile X syndrome pathophysiology

Fragile X Syndrome (FXS) results from the silencing of the FMR1 gene and is the most prevalent inherited cause of intellectual disability and the most frequent monogenic cause of autism spectrum disorder. It is well established that Fragile X individuals are subjected to a wide array of comorbidities, ranging from cognitive, behavioural, and medical origin. Furthermore, recent studies have also described metabolic impairments in FXS individuals. However, the molecular mechanisms linking FMRP deficiency to improper metabolism are still misunderstood. The endocannabinoidome (eCBome) is a lipid-based signalling system that regulates several functions across the body, ranging from cognition, behaviour and metabolism. Alterations in the eCBome have been described in FXS animal models and linked to neuronal hyperexcitability, a core deficit of the disease. However, the potential link between dysregulation of the eCBome and altered metabolism observed in FXS remains unexplored. As such, this review aims to overcome this issue by describing the most recent finding related to eCBome and metabolic dysfunctions in the context of FXS. A better comprehension of this association will help deepen our understanding of FXS pathophysiology and pave the way for future therapeutic interventions.

Engineering magnetic nanosystem for TRPV1 and TRPV4 channel activation

Recently, physical tools for remotely stimulating mechanical force-sensitive and temperature-sensitive proteins to regulate intracellular pathways have opened up novel and exciting avenues for basic research and clinical applications. Among the numerous modes of physical stimulation, magnetic stimulation is significantly attractive for biological applications due to the advantages of depth penetration and spatial-temporally controlled transduction. Herein, the physicochemical parameters (e.g., shape, size, composition) that influence the magnetic properties of magnetic nanosystems as well as the characteristics of transient receptor potential vanilloid-1 (TRPV1) and transient receptor potential vanilloid-4 (TRPV4) channels are systematically summarized, which offer opportunities for magnetic manipulation of cell fate in a precise and effective manner. In addition, representative regulatory applications involving magnetic nanosystem-based TRPV1 and TRPV4 channel activation are highlighted, both at the cellular level and in animal models. Furthermore, perspectives on the further development of this magnetic stimulation mode are commented on, with emphasis on scientific limitations and possible directions for exploitation. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Lipopolysaccharide pretreatment increases the sensitivity of the TRPV1 channel and promotes an anti-inflammatory phenotype of capsaicin-activated macrophages

BACKGROUND

The transient receptor potential vanilloid 1 (TRPV1) is well-established in neuronal function, yet its role in immune reactions remains enigmatic. The conflicting data on its inflammatory role, suggesting both pro-inflammatory and anti-inflammatory effects upon TRPV1 stimulation in immune cells, adds complexity. To unravel TRPV1 immunomodulatory mechanisms, we investigated how the TRPV1 agonist capsaicin influences lipopolysaccharide (LPS)-induced pro-inflammatory macrophage phenotypes.

RESULTS

Changes in the surface molecules, cytokine production, and signaling cascades linked to the phenotype of M1 or M2 macrophages of the J774 macrophage cell line and bone marrow-derived macrophages, treated with capsaicin before or after the LPS-induced inflammatory reaction were determined. The functional capacity of macrophages was also assessed by infecting the stimulated macrophages with the intracellular parasite Leishmania mexicana.

CONCLUSION

Our findings reveal that TRPV1 activation yields distinct macrophage responses influenced by the inflammatory context. LPS pre-treatment followed by capsaicin activation prompted increased calcium influx, accompanied by a shift toward an anti-inflammatory M2b-like polarization state.

Hemp Seed Oil Inhibits the Adipogenicity of the Differentiation-Induced Human Mesenchymal Stem Cells through Suppressing the Cannabinoid Type 1 (CB1)

Central and peripheral mechanisms of the endocannabinoid system (ECS) favor energy intake and storage. The ECS, especially cannabidiol (CBD) receptors, controls adipocyte differentiation (hyperplasia) and lipid accumulation (hypertrophy) in adipose tissue. In white adipose tissue, cannabidiol receptor 1 (CB1) stimulation increases lipogenesis and inhibits lipolysis; in brown adipose tissue, it decreases mitochondrial thermogenesis and biogenesis. This study compared the availability of phytocannabinoids [CBD and Δ9-tetrahydrocannabinol (THC)] and polyunsaturated fatty acids [omega 3 (ω3) and omega 6 (ω6)] in different hemp seed oils (HSO). The study also examined the effect of HSO on adipocyte lipid accumulation by suppressing cannabinoid receptors in adipogenesis-stimulated human mesenchymal stem cells (hMSCs). Most importantly, Oil-Red-O' and Nile red tests showed that HSO induced adipogenic hMSC differentiation without differentiation agents. Additionally, HSO-treated cells showed increased peroxisome proliferator-activated receptor gamma (PPARγ) mRNA expression compared to controls (hMSC). HSO reduced PPARγ mRNA expression after differentiation media (DM) treatment. After treatment with HSO, DM-hMSCs had significantly lower CB1 mRNA and protein expressions than normal hMSCs. HSO treatment also decreased transient receptor potential vanilloid 1 (TRPV1), fatty acid amide hydrolase (FAAH), and monoacylglycerol lipase (MGL) mRNAs in hMSC and DM-hMSCs. HSO treatment significantly decreased CB1, CB2, TRPV1, and G-protein-coupled receptor 55 (GPCR55) protein levels in DM-hMSC compared to hMSC in western blot analysis. In this study, HSO initiated adipogenic differentiation in hMSC without DM, but it suppressed CB1 gene and protein expression, potentially decreasing adipocyte lipid accumulation and lipogenic enzymes.

Amide Alkaloids as Privileged Sources of Senomodulators for Therapeutic Purposes in Age-Related Diseases

Nature is an important source of bioactive compounds and has continuously made a large contribution to the discovery of new drug leads. Particularly, plant-derived compounds have long been identified as highly interesting in the field of aging research and senescence. Many plants contain bioactive compounds that have the potential to influence cellular processes and provide health benefits. Among them, Piper alkaloids have emerged as interesting candidates in the context of age-related diseases and particularly senescence. These compounds have been shown to display a variety of features, including antioxidant, anti-inflammatory, neuroprotective, and other bioactive properties that may help counteracting the effects of cellular aging processes. In the review, we will put the emphasis on piperlongumine and other related derivatives, which belong to the Piper alkaloids, and whose senomodulating potential has emerged during the last several years. We will also provide a survey on their potential in therapeutic perspectives of age-related diseases.

Structural and functional characterisation of Tst2, a novel TRPV1 inhibitory peptide from the Australian sea anemone Telmatactis stephensoni

Sea anemone venoms are complex mixtures of biologically active compounds, including disulfide-rich peptides, some of which have found applications as research tools, and others as therapeutic leads. Our recent transcriptomic and proteomic studies of the Australian sea anemone Telmatactis stephensoni identified a transcript for a peptide designated Tst2. Tst2 is a 38-residue peptide showing sequence similarity to peptide toxins known to interact with a range of ion channels (NaV, TRPV1, KV and CaV). Recombinant Tst2 (rTst2, which contains an additional Gly at the N-terminus) was produced by periplasmic expression in Escherichia coli, enabling the production of both unlabelled and uniformly 13C,15N-labelled peptide for functional assays and structural studies. The LC-MS profile of the recombinant Tst2 showed a pure peak with molecular mass 6 Da less than that of the reduced form of the peptide, indicating the successful formation of three disulfide bonds from its six cysteine residues. The solution structure of rTst2 was determined using multidimensional NMR spectroscopy and revealed that rTst2 adopts an inhibitor cystine knot (ICK) structure. rTst2 was screened using various functional assays, including patch-clamp electrophysiological and cytotoxicity assays. rTst2 was inactive against voltage-gated sodium channels (NaV) and the human voltage-gated proton (hHv1) channel. rTst2 also did not possess cytotoxic activity when assessed against Drosophila melanogaster flies. However, the recombinant peptide at 100 nM showed >50% inhibition of the transient receptor potential subfamily V member 1 (TRPV1) and slight (∼10%) inhibition of transient receptor potential subfamily A member 1 (TRPA1). Tst2 is thus a novel ICK inhibitor of the TRPV1 channel.

Piperine Attenuates Bmal1-Mediated Glucose Metabolism Disorder in a Trpv1-Dependent Manner in HepG2 Cells

Piperine (PIP), a pungent alkaloid found in black pepper, has various pharmacological effects by activating the transient receptor potential vanilloid 1 (TRPV1) receptor. In this study, the regulating effect of PIP on glucose metabolism and the underlying mechanism were examined using an insulin-resistant cell model. Results showed that PIP alleviated glucosamine (GlcN)-induced glucose metabolism disorder (from 59.19 ± 1.90 to 88.36 ± 6.57%), restored cellular redox balance (from 148.43 ± 3.52 to 110.47 ± 3.52%), improved mitochondrial function (from 63.76 ± 4.87 to 85.98 ± 5.12%), and mitigated circadian disruption in HepG2 cells via the mediation of circadian clock gene Bmal1. After the knockdown of the Trpv1 gene, the modulating effect of PIP on Bmal1-mediated glucose metabolism was weakened, indicating that PIP alleviated Bmal1-involved insulin resistance and circadian misalignment in a Trpv1-dependent manner in HepG2 cells.

Plant polyphenol extract supplementation affects performance, welfare, and the Nrf2-oxidative stress response in adipose tissue of heat-stressed dairy cows

We examined the effects of a supplement of plant polyphenols extracts of green tea, capsicum, and fenugreek, and electrolytes ([Na+, K+]; AXT, Axion ThermoPlus, CCPA, France] during summer heat load on production, welfare, and oxidative stress proteins in adipose tissue (AT) of dairy cows. A total of 42 multiparous mid-lactation cows were divided into 3 groups during summer, and were fed for 2 wk either a standard milking cow diet (CTL, n = 14) or diets supplemented with 100 g/d of AXT (100AXT, n = 14), or 150 g/d of AXT (150AXT, n = 14), while being cooled 5 times a day. Then, half of the cows from each dietary treatment were cooled (CL) or not cooled (NCL) for 2 wk, after which the cooled and uncooled groups were switched for additional 2 wk. Cows were milked 3 times a day, and milk composition was analyzed at the end of each 2-wk period. Vaginal temperature (VT) was measured for 3 consecutive days in each period. Biopsies of subcutaneous AT were taken from 10 NCL cows (5 each of CTL and 150AXT) at the end of the period and examined by liquid chromatography-tandem mass spectrometry proteomics analysis. Data were analyzed with PROC MIXED of SAS (version 9.2, SAS Institute Inc.). The model included the effects of dietary treatment, cooling regimen, period, and their interactions. Protein and mRNA abundances and proteomic data (P ≤ 0.05 and fold change [FC] ± 1.5) were analyzed by t-test. Milk yields and 4% fat-corrected milk (FCM) were higher in 100AXT than in CTL; milk components were not different. Dry matter intake (DMI) was higher in 100AXT than in CTL. The effect of cooling and the interactions of period × cooling were significant for DMI, 4% FCM, energy-corrected milk, and milk/DMI. The proportion of time that VT was >39°C was lower in 100AXT and in 150AXT than in CTL. Daily rumination time was greater in 150AXT than in CTL, and lying time was greater in 100AXT and 150AXT than in CTL. Proteomics of AT demonstrated that 150AXT had increased abundances of peroxidasin (FC = 1.6), microsomal glutathione S-transferase 2 (FC = 2.5), and heme oxygenase 1 (FC = 3.6) compared with CTL. Top enriched canonical pathways included acute phase response signaling, Nrf2-mediated oxidative stress response, and lipopolysaccharide (LPS)/IL-1-mediated inhibition of RXR function. Immunoblots of AT showed a higher abundance of the transient receptor potential vanilloid 1 and of LPS binding protein in AT of 150AXT compared with CTL. Supplementation of AXT increased DMI, milk, and 4% FCM, lowered VT, improved welfare indices, and enriched the AT with Nrf2-oxidative stress response and acute phase response proteins in heat-stressed dairy cows.

Comprehensive insights into the multifaceted roles of the transient receptor potential vanilloid 1 channel in the digestive system

The transient receptor potential vanilloid (TRPV) channel, a family of calcium transporters comprising six distinct members (TRPV1-6), takes on a paramount role in maintaining intracellular Ca2+ homeostasis in mammalian cells. Notably, TRPV1, among its counterparts, has emerged as the subject of extensive scrutiny, owing to its pervasive presence in diverse cellular, tissue, and organ settings. This ubiquitous distribution underscores its fundamental involvement in the genesis of pain, making it a central focus in pain-related research. However, recent investigations have unveiled that TRPV1's functional significance transcends the realm of pain modulation, extending its influence to encompass a wide spectrum of physiological and pathological processes. The ambit of TRPV1's influence encompasses not only pain responses but also embraces the intricate domains of nervous system disorders, cancer metastasis, as well as afflictions pertaining to the skin and heart. Moreover, compelling evidence now demonstrates that TRPV1 also wields substantial sway in the domain of digestive diseases, further highlighting its versatility and far-reaching impact on human health. Therefore, this comprehensive review endeavors to delve into the multifaceted roles played by TRPV1 in the various organs constituting the digestive system.

The metabolic and functional roles of sensory nerves in adipose tissues

Homeostatic regulation of adipose tissue is critical for the maintenance of energy balance and whole-body metabolism. The peripheral nervous system provides bidirectional neural communication between the brain and adipose tissue, thereby providing homeostatic control. Most research on adipose innervation and nerve functions has been limited to the sympathetic nerves and their neurotransmitter norepinephrine. In recent years, more work has focused on adipose sensory nerves, but the contributions of subsets of sensory nerves to metabolism and the specific roles contributed by sensory neuropeptides are still understudied. Advances in imaging of adipose innervation and newer tissue denervation techniques have confirmed that sensory nerves contribute to the regulation of adipose functions, including lipolysis and browning. Here, we summarize the historical and latest findings on the regulation, function and plasticity of adipose tissue sensory nerves that contribute to metabolically important processes such as lipolysis, vascular control and sympathetic axis cross-talk.

Novel N-Acylethanolamide Derivatives Affect Body Weight and Energy Balance

Introduction - The obesity pandemic is multifactorial. Nutritional, pharmacologic and surgical interventions are limited in reach and efficacy, raising need for new therapeutics. Aims - Characterization of anorexigenic and cognitive effect and central mechanism of action of novel N-acylethanolamide derivatives. Methods - Sabra mice divided to similar experimental groups, injected IP with: oleyl-L-leucinolamide (1 A), linoleyl-L-leucinolamide (4 A), linoleyl-L-valinolamide (5 A), oleyl-oxycarbonyl-L-valinolamide (1 B), oleyl-oxycarbonyl-D-valinolamide (2 B), oleylamine-carbonyl-L-valinolamide (3 B), oleylamine-carbonyl-D-valinolamide (4 B), and oleyl-L-hydroxyvalineamide (5 B). Control group with vehicle. Body weight and food consumption followed for 39 days. Motor activity and cognitive function by open field test and eight-arm maze. Mice sacrificed and mechanism of action investigated by qPCR. The genes analyzed involved in energy balance and regulation of appetite. Catecholamines and serotonin evaluated. Results - Compounds 1 A, 5 A, 1 B-4 B, caused significant weight loss of 4.2-5.6 % and 5 A, 1 B-4 B, improved cognitive function following 8 i. p. injections of 1 mg/kg during 39 days, by different mechanisms. 5 A, 3 B and 4 B decreased food consumption, whereas 1 A, 5 A and 2 B increased motor activity. 1 A, 4 A, 1 B and 3 B elevated SIRT-1, associated with survival. POMC upregulated by 1 B and 2 B, CART by 1 B, 2 B and 1 A. NPY and CAMKK2 downregulated by 5 A. 4 B enhanced 5-HT levels. 4 A, 5 A, 1 B, 4 B, 5 B decreased FAAH, showing long lasting effect. Conclusions - These new compounds might be developed for the treatment of obesity and for improved cognitive function.

Changes in plasma endocannabinoids concentrations correlate with 18F-FDG PET/MR uptake in brown adipocytes in humans

Introduction: Recent data suggest a possible role of endocannabinoids in the regulation of brown adipose tissue (BAT) activity. Those findings indicate potential treatment options for obesity. The aim of this study was to evaluate the relationship between plasma endocannabinoids concentrations and the presence of BAT in humans. Methods: The study group consisted of 25 subjects divided into two groups: BAT positive BAT(+), (n = 17, median age = 25 years) and BAT negative BAT(-), (n = 8, median age = 28 years). BAT was estimated using 18F-FDG PET/MR after 2 h of cold exposure. The level of plasma endocannabinoids was assessed at baseline, 60 min and 120 min of cold exposure. Results: In both groups, BAT(+) and BAT(-), during the cooling, we observed a decrease of the same endocannabinoids: arachidonoylethanolamide (AEA), eicosapentaenoyl ethanolamide (EPEA) and oleoyl ethanolamide (OEA) with a much more profound decline in BAT(+) subjects. Statistically significant fall of PEA (palmitoylethanolamide) and SEA (stearoylethanolamide) concentrations after 60 min (FC = 0.7, p = 0.007 and FC = 0.8, p = 0.03, respectively) and 120 min (FC = 0.81, p = 0.004, and FC = 0.9, p = 0.01, respectively) of cooling was observed only in individuals with BAT. Conclusion: We noticed the profound decline of endocannabinoids concentrations in subjects with increased 18F-FDG PET/MR uptake in BAT. Identification of a new molecules related to BAT activity may create a new target for obesity treatment.

"ThermoTRP" Channel Expression in Cancers: Implications for Diagnosis and Prognosis (Practical Approach by a Pathologist)

Temperature-sensitive transient receptor potential (TRP) channels (so-called "thermoTRPs") are multifunctional signaling molecules with important roles in cell growth and differentiation. Several "thermoTRP" channels show altered expression in cancers, though it is unclear if this is a cause or consequence of the disease. Regardless of the underlying pathology, this altered expression may potentially be used for cancer diagnosis and prognostication. "ThermoTRP" expression may distinguish between benign and malignant lesions. For example, TRPV1 is expressed in benign gastric mucosa, but is absent in gastric adenocarcinoma. TRPV1 is also expressed both in normal urothelia and non-invasive papillary urothelial carcinoma, but no TRPV1 expression has been seen in invasive urothelial carcinoma. "ThermoTRP" expression can also be used to predict clinical outcomes. For instance, in prostate cancer, TRPM8 expression predicts aggressive behavior with early metastatic disease. Furthermore, TRPV1 expression can dissect a subset of pulmonary adenocarcinoma patients with bad prognosis and resistance to a number of commonly used chemotherapeutic agents. This review will explore the current state of this rapidly evolving field with special emphasis on immunostains that can already be added to the armoire of diagnostic pathologists.

Local Inflammatory Mediators Involved in Neuropathic Pain

Polyneuropathy (PNP) is a term to describe diseases of the peripheral nervous system, 50% of which present with neuropathic pain. In some types of PNP, pain is restricted to the skin distally in the leg, suggesting a local regulatory process leading to pain. In this study, we proposed a pro-inflammatory pathway mediated by NF-κB that might be involved in the development of pain in patients with painful PNP. To test this hypothesis, we have collected nerve and skin samples from patients with different etiologies and levels of pain. We performed RT-qPCR to analyze the gene expression of the proposed inflammatory pathway components in sural nerve and in distal and proximal skin samples. In sural nerve, we showed a correlation of TLR4 and TNFα to neuropathic pain, and an upregulation of TNFα in patients with severe pain. Patients with an inflammatory PNP also presented a lower expression of TRPV1 and SIRT1. In distal skin, we found a reduced expression of TLR4 and miR-146-5p, in comparison to proximal skin. Our findings thus support our hypothesis of local inflammatory processes involved in pain in PNP, and further show disturbed anti-inflammatory pathways involving TRPV1 and SIRT1 in inflammatory PNP.

Capsaicin and Zinc Signalling Pathways as Promising Targets for Managing Insulin Resistance and Type 2 Diabetes

The global burden of type 2 diabetes (T2DM) has led to significant interest in finding novel and effective therapeutic targets for this chronic disorder. Bioactive food components have effectively improved abnormal glucose metabolism associated with this disease. Capsaicin and zinc are food components that have shown the potential to improve glucose metabolism by activating signalling events in the target cells. Capsaicin and zinc stimulate glucose uptake through the activation of distinct pathways (AMPK and AKT, respectively); however, calcium signal transduction seems to be the common pathway between the two. The investigation of molecular pathways that are activated by capsaicin and zinc has the potential to lead to the discovery of new therapeutic targets for T2DM. Therefore, this literature review aims to provide a summary of the main signalling pathways triggered by capsaicin and zinc in glucose metabolism.

Brown Adipose Tissue-A Translational Perspective

Brown adipose tissue (BAT) displays the unique capacity to generate heat through uncoupled oxidative phosphorylation that makes it a very attractive therapeutic target for cardiometabolic diseases. Here, we review BAT cellular metabolism, its regulation by the central nervous and endocrine systems and circulating metabolites, the plausible roles of this tissue in human thermoregulation, energy balance, and cardiometabolic disorders, and the current knowledge on its pharmacological stimulation in humans. The current definition and measurement of BAT in human studies relies almost exclusively on BAT glucose uptake from positron emission tomography with 18F-fluorodeoxiglucose, which can be dissociated from BAT thermogenic activity, as for example in insulin-resistant states. The most important energy substrate for BAT thermogenesis is its intracellular fatty acid content mobilized from sympathetic stimulation of intracellular triglyceride lipolysis. This lipolytic BAT response is intertwined with that of white adipose (WAT) and other metabolic tissues, and cannot be independently stimulated with the drugs tested thus far. BAT is an interesting and biologically plausible target that has yet to be fully and selectively activated to increase the body's thermogenic response and shift energy balance. The field of human BAT research is in need of methods able to directly, specifically, and reliably measure BAT thermogenic capacity while also tracking the related thermogenic responses in WAT and other tissues. Until this is achieved, uncertainty will remain about the role played by this fascinating tissue in human cardiometabolic diseases.

Progress in the Structural Basis of thermoTRP Channel Polymodal Gating

The thermosensory transient receptor potential (thermoTRP) family of ion channels is constituted by several nonselective cation channels that are activated by physical and chemical stimuli functioning as paradigmatic polymodal receptors. Gating of these ion channels is achieved through changes in temperature, osmolarity, voltage, pH, pressure, and by natural or synthetic chemical compounds that directly bind to these proteins to regulate their activity. Given that thermoTRP channels integrate diverse physical and chemical stimuli, a thorough understanding of the molecular mechanisms underlying polymodal gating has been pursued, including the interplay between stimuli and differences between family members. Despite its complexity, recent advances in cryo-electron microscopy techniques are facilitating this endeavor by providing high-resolution structures of these channels in different conformational states induced by ligand binding or temperature that, along with structure-function and molecular dynamics, are starting to shed light on the underlying allosteric gating mechanisms. Because dysfunctional thermoTRP channels play a pivotal role in human diseases such as chronic pain, unveiling the intricacies of allosteric channel gating should facilitate the development of novel drug-based resolving therapies for these disorders.

Mechanism and potential treatments for gastrointestinal dysfunction in patients with COVID-19

The global coronavirus disease 2019 (COVID-19) has become one of the biggest threats to the world since 2019. The respiratory and gastrointestinal tracts are the main targets for severe acute respiratory syndrome coronavirus 2 infection for they highly express angiotensin-converting enzyme-2 and transmembrane protease serine 2. In patients suffering from COVID-19, gastrointestinal symptoms have ranged from 12% to 61%. Anorexia, nausea and/or vomiting, diarrhea, and abdominal pain are considered to be the main gastrointestinal symptoms of COVID-19. It has been reported that the direct damage of intestinal mucosal epithelial cells, malnutrition, and intestinal flora disorders are involved in COVID-19. However, the underlying mechanisms remain unclear. Thus, in this study, we reviewed and discussed the correlated mechanisms that cause gastrointestinal symptoms in order to help to develop the treatment strategy and build an appropriate guideline for medical workers.

Impact of selenium on the intestinal microbiome-eCBome axis in the context of diet-related metabolic health in mice

Dietary micronutrients act at the intestinal level, thereby influencing microbial communities, the host endocannabinoidome, and immune and anti-oxidative response. Selenium (Se) is a trace element with several health benefits. Indeed, Se plays an important role in the regulation of enzymes with antioxidative and anti-inflammatory activity as well as indicators of the level of oxidative stress, which, together with chronic low-grade inflammation, is associated to obesity. To understand how Se variations affect diet-related metabolic health, we fed female and male mice for 28 days with Se-depleted or Se-enriched diets combined with low- and high-fat/sucrose diets. We quantified the plasma and intestinal endocannabinoidome, profiled the gut microbiota, and measured intestinal gene expression related to the immune and the antioxidant responses in the intestinal microenvironment. Overall, we show that intestinal segment-specific microbiota alterations occur following high-fat or low-fat diets enriched or depleted in Se, concomitantly with modifications of circulating endocannabinoidome mediators and changes in cytokine and antioxidant enzyme expression. Specifically, Se enrichment was associated with increased circulating plasma levels of 2-docosahexaenoyl-glycerol (2-DHG), a mediator with putative beneficial actions on metabolism and inflammation. Others eCBome mediators also responded to the diets. Concomitantly, changes in gut microbiota were observed in Se-enriched diets following a high-fat diet, including an increase in the relative abundance of Peptostreptococcaceae and Lactobacillaceae. With respect to the intestinal immune response and anti-oxidative gene expression, we observed a decrease in the expression of proinflammatory genes Il1β and Tnfα in high-fat Se-enriched diets in caecum, while in ileum an increase in the expression levels of the antioxidant gene Gpx4 was observed following Se depletion. The sex of the animal influenced the response to the diet of both the gut microbiota and endocannabinoid mediators. These results identify Se as a regulator of the gut microbiome and endocannabinoidome in conjunction with high-fat diet, and might be relevant to the development of new nutritional strategies to improve metabolic health and chronic low-grade inflammation associated to metabolic disorders.

Feeding encapsulated pepper to dairy cows during the hot season improves performance without affecting core and skin temperature

Peppers (Capsicum spp.) contain capsaicin, an organic compound with a group of alkaloids that has shown thermoregulation properties in humans and mice, and may influence glucose and lipid metabolism in ruminants. An experiment was conducted to evaluate different doses of a feed additive containing encapsulated pepper on milk yield and composition, dry matter intake, feed sorting index, total-tract apparent digestibility of nutrients, purine derivatives excretion, and serum concentrations of urea-N and glucose, N excretion, respiration rate, rectal temperature, and skin temperature in different regions (forehead, face, and rumen). Thirty-six Holstein cows (150 ± 102.1 d in milk and 29.3 ± 5.81 kg/d milk yield) were used in a 9-wk randomized complete block (n = 12) design experiment. Following a 2-wk covariate period, cows were blocked according to parity, days in milk, and milk yield and were randomly assigned to the following treatments: 0 (CAP0), 0.75 (CAP75), or 1.5 (CAP150) g/d of a feed additive containing encapsulated pepper (1 g/kg, Capcin; NutriQuest) added to the concentrate along with minerals. Treatment differences were evaluated through orthogonal contrasts (CAP0 vs. CAP75 + CAP150 or CAP75 vs. CAP150). The average temperature-humidity index during the experiment was 72.0 ± 2.07. Dry matter intake was greater in cows fed a feed additive containing encapsulated pepper (CAP) treatments (CAP75 and CAP150) compared with CAP0. Cows fed CAP150 tended to have greater dry matter intake than those in CAP75 group. Feeding CAP decreased sorting for feed particles with size between 8 and 4 mm. An interaction effect between treatment and week was observed for crude protein digestibility whereas cows fed CAP150 had the greatest digestibility on the third week of experiment. Orthogonal contrasts did not detect differences in serum concentrations of glucose and urea-N, or purine derivatives excretion. Nitrogen excretion (as % of N intake) in milk, urine, and feces was not altered by treatments. Feeding CAP increased yields of 3.5% fat-corrected milk, fat, protein, and lactose. A tendency toward greater milk protein content was observed for cows fed CAP150 than CAP75. No differences were detected on respiration rate, rectal temperature, and skin temperature of cows. A feed additive containing encapsulated pepper fed at 0.75 or 1.5 g/d can improve yield of fat-corrected milk and milk solids by increasing feed intake without affecting nutrient digestibility and body temperature of lactating cows during the hot season.

Endocannabinoid receptors are involved in enhancing food intake in rainbow trout

The mechanisms involved in hedonic regulation of food intake, including endocannabinoid system (ECs) are scarcely known in fish. We recently demonstrate in rainbow trout the presence of a rewarding response mediated by ECs in hypothalamus and telencephalon when fish fed a lipid-enriched diet, and that central administration of main agonists of ECs namely AEA or 2-AG exert a bimodal effect on feed intake in fish with low doses inducing an increase that disappears with the high dose of both endocannabinoids (EC). To assess the precise involvement of the different receptors of the ECs (CNR1, TRPV1, and GPR55) in this response we injected intracerebroventricularly AEA or 2-AG in the absence/presence of specific receptor antagonists (AM251, capsazepine, and ML193; respectively). The presence of antagonists clearly counteracts the effect of EC supporting the specificity of EC action inducing changes not only in ECs but also in GABA and glutamate metabolism ultimately leading to the increase observed in food intake response.

Lack of TRPV1 Channel Modulates Mouse Gene Expression and Liver Proteome with Glucose Metabolism Changes

To investigate the role of the transient receptor potential channel vanilloid type 1 (TRPV1) in hepatic glucose metabolism, we analyzed genes related to the clock system and glucose/lipid metabolism and performed glycogen measurements at ZT8 and ZT20 in the liver of C57Bl/6J (WT) and Trpv1 KO mice. To identify molecular clues associated with metabolic changes, we performed proteomics analysis at ZT8. Liver from Trpv1 KO mice exhibited reduced Per1 expression and increased Pparα, Pparγ, Glut2, G6pc1 (G6pase), Pck1 (Pepck), Akt, and Gsk3b expression at ZT8. Liver from Trpv1 KO mice also showed reduced glycogen storage at ZT8 but not at ZT20 and significant proteomics changes consistent with enhanced glycogenolysis, as well as increased gluconeogenesis and inflammatory features. The network propagation approach evidenced that the TRPV1 channel is an intrinsic component of the glucagon signaling pathway, and its loss seems to be associated with increased gluconeogenesis through PKA signaling. In this sense, the differentially identified kinases and phosphatases in WT and Trpv1 KO liver proteomes show that the PP2A phosphatase complex and PKA may be major players in glycogenolysis in Trpv1 KO mice.

An active ingredient isolated from Ganoderma lucidum promotes burn wound healing via TRPV1/SMAD signaling

The mushroom Ganoderma lucidum is a traditional Chinese medicine and G. lucidum spore oil (GLSO) is the lipid fraction isolated from Ganoderma spores. We examined the effect of GLSO on burn wound healing in mice. Following wounding, GLSO was applied on the wounds twice daily. Repair analysis was performed by Sirius-Red-staining at different time points. Cell proliferation and migration assays were performed to verify the effect of GLSO on growth. Network pharmacology analysis to identify possible targets was also carried out, followed by Western blotting, nuclear translocation, cell proliferation, and immunofluorescence assays for in-depth investigation of the mechanism. Our study showed that GLSO significantly promoted cell proliferation, and network pharmacology analysis suggested that GLSO might act through transient receptor potential vanilloid receptor 1 (TRPV1)/SMAD signaling. Furthermore, GLSO elevated SMAD2/3 expression in skin burn and promoted its nuclear translocation, and TRPV1 expression was also increased upon exposure to GLSO. Cell proliferation and immunofluorescence assays with TRPV1 inhibitor showed that GLSO accelerated skin burn wound healing through TRPV1 and SMADs signaling, which provides a foundation for clinical application of GLSO in the healing of deep skin burns.

Effects of Environmental Heat Load on Endocannabinoid System Components in Adipose Tissue of High Yielding Dairy Cows

Environmental heat load (HL) adversely affects the performance of dairy cows. The endocannabinoid system (ECS) regulates metabolism and the stress response, thus we hypothesized that HL may affect the ECS of dairy cows. Our objective was to determine the levels of endocannabinoids (eCBs) and gene and protein expressions of the ECS components in adipose tissue (AT) and plasma of early postpartum (PP) and late-lactation cows. In addition, we examined eCBs in milk, and studied the interaction of eCBs with bovine cannabinoids receptors CB1 and CB2. In the first experiment, plasma and AT were sampled from cows calving during summer (S, n = 9) or winter (W, n = 9). Dry matter intake (DMI) and energy balance (EB) were lower in S vs. W, and relative gene expressions of transient-receptor-potential-cation-channel-subfamily-V-member-1 (TRPV1), the cannabinoid receptors CNR1 (CB1) and CNR2 (CB2), and monoglyceride lipase (MGLL) were decreased in AT of S compared to W. Protein abundance of peroxisome proliferator-activated-receptor-alpha (PPAR-α) was decreased, while tumor-necrosis factor-α (TNF-α) was increased in AT of S vs. W. Other components of the ECS were not different between S and W calving cows. To study whether the degree of HL may affect the ECS, we performed a second experiment with 24 late-lactation cows that were either cooled (CL) or not cooled (heat-stressed; HS) during summer. DMI was lower in HS vs. CL, AT protein abundance of PPAR-α was lower, and TRPV1 tended to be lower in HS vs. CL, but other components of the ECS were not different between groups. Milk levels of 2-arachidonoylglycerol (2-AG) tended to increase in HS vs. CL. Additionally, modeling of the bovine cannabinoid receptors demonstrated their binding to anandamide and 2-AG. Environmental HL, possibly via lower intake, is associated with limited alterations in ECS components in AT of dairy cows.

The Endocannabinoid System and Physical Activity—A Robust Duo in the Novel Therapeutic Approach against Metabolic Disorders

Rapidly increasing worldwide prevalence of obesity and related pathologies encompassing coronary heart disease, hypertension, metabolic syndrome, or type 2 diabetes constitute serious threats to global health and are associated with a significantly elevated risk of premature death. Considering the enormous burden of these pathologies, novel therapeutic and preventive patterns are indispensable. Dysregulation of one of the most complex biological systems in the human body namely, the endocannabinoid system (ECS) may result in metabolic imbalance and development of insulin resistance, type 2 diabetes, or non-alcoholic fatty liver disease. Furthermore, many studies showed that physical exercises, depending on their type, intensity, and frequency, exert various alterations within the ECS. Emerging evidence suggests that targeting the ECS via physical activity may produce robust beneficial effects on the course of metabolic pathologies. However, the data showing a direct correlation between the ECS and physical activity in the aspect of metabolic health are very scarce. Therefore, the aim of this review was to provide the most up-to-date state of knowledge about the interplay between the ECS activity and physical exercises in the novel therapeutic and preventive approach toward metabolic pathologies. We believe that this paper, at least in part, will fulfill the existing gap in knowledge and encourage researchers to further explore this very complex yet interesting link between the ECS, its action in physical activity, and subsequent positive outcomes for metabolic health.

TRPV1 Contributes to Modulate the Nitric Oxide Pathway and Oxidative Stress in the Isolated and Perfused Rat Heart during Ischemia and Reperfusion

The transient vanilloid receptor potential type 1 (TRPV1) regulates neuronal and vascular functions mediated by nitric oxide (NO) and by the calcitonin gene-related peptide (CGRP). Here, we study the participation of TRPV1 in the regulation of myocardial injury caused by ischemia-reperfusion and in the control of NO, tetrahydrobiopterin (BH4), the cGMP pathway, CGRP, total antioxidant capacity (TAC), malondialdehyde (MDA) and phosphodiesterase-3 (PDE-3). Isolated hearts of Wistar rats perfused according to the Langendorff technique were used to study the effects of an agonist of TRPV1, capsaicin (CS), an antagonist, capsazepine (CZ), and their combination CZ+CS. The hearts were subjected to three conditions: (1) control, (2) ischemia and (3) ischemia-reperfusion. We determined cardiac mechanical activity and the levels of NO, cGMP, BH4, CGRP, TAC, MDA and PDE-3 in ventricular tissue after administration of CS, CZ and CZ+CS. Western blots were used to study the expressions of eNOS, iNOS and phosphorylated NOS (pNOS). Structural changes were determined by histological evaluation. CS prevented damage caused by ischemia-reperfusion by improving cardiac mechanical activity and elevating the levels of NO, cGMP, BH4, TAC and CGRP. TRPV1 and iNOS expression were increased under ischemic conditions, while eNOS and pNOS were not modified. We conclude that the activation of TRPV1 constitutes a therapeutic possibility to counteract the damage caused by ischemia and reperfusion by regulating the NO pathway through CGRP.

Mutual Links between the Endocannabinoidome and the Gut Microbiome, with Special Reference to Companion Animals: A Nutritional Viewpoint

There is growing evidence that perturbation of the gut microbiome, known as “dysbiosis”, is associated with the pathogenesis of human and veterinary diseases that are not restricted to the gastrointestinal tract. In this regard, recent studies have demonstrated that dysbiosis is linked to the pathogenesis of central neuroinflammatory disorders, supporting the existence of the so-called microbiome-gut-brain axis. The endocannabinoid system is a recently recognized lipid signaling system and termed endocannabinoidome monitoring a variety of body responses. Accumulating evidence demonstrates that a profound link exists between the gut microbiome and the endocannabinoidome, with mutual interactions controlling intestinal homeostasis, energy metabolism and neuroinflammatory responses during physiological conditions. In the present review, we summarize the latest data on the microbiome-endocannabinoidome mutual link in health and disease, focalizing the attention on gut dysbiosis and/or altered endocannabinoidome tone that may distort the bidirectional crosstalk between these two complex systems, thus leading to gastrointestinal and metabolic diseases (e.g., idiopathic inflammation, chronic enteropathies and obesity) as well as neuroinflammatory disorders (e.g., neuropathic pain and depression). We also briefly discuss the novel possible dietary interventions based not only on probiotics and/or prebiotics, but also, and most importantly, on endocannabinoid-like modulators (e.g., palmitoylethanolamide) for intestinal health and beyond.

The Expanded Endocannabinoid System Contributes to Metabolic and Body Mass Shifts in First-Episode Schizophrenia: A 5-Year Follow-Up Study

Alterations in the expanded endocannabinoid system (eECS) and cell membrane composition have been implicated in the pathophysiology of schizophrenia spectrum disorders. We enrolled 54 antipsychotic (AP)-naïve first-episode psychosis (FEP) patients and 58 controls and applied a targeted metabolomics approach followed by multivariate data analysis to investigate the profile changes in the serum levels of endocannabinoids: 2-arachidonoylglycerol (2-AG) and anandamide, endocannabinoids-like N-acylethanolamines (NAEs: linoleoylethanolamide, oleoylethanolamide, and palmitoylethanolamide), and their dominating lipid precursor’s phosphatidylcholines. Biomolecule profiles were measured at the onset of first-episode psychosis (FEP) and 0.6 years and 5.1 years after the initiation of AP treatment. The results indicated that FEP might be characterized by elevated concentrations of NAEs and by decreased 2-AG levels. At this stage of the disease, the NAE-mediated upregulation of peroxisome proliferator-activated receptors (PPARs) manifested themselves in energy expenditure. A 5-year disease progression and AP treatment adverse effects led to a robust increase in 2-AG levels, which contributed to strengthened cannabinoid (CB1) receptor-mediated effects, which manifested in obesity. Dynamic 2-AG, NAEs, and their precursors in terms of phosphatidylcholines are relevant to the description of the metabolic shifts resulting from the altered eECS function during and after FEP.

Modulatory role of the endocannabinoidome in the pathophysiology of the gastrointestinal tract

Originating from Eastern Asia, the plant Cannabis sativa has been used for centuries as a medicinal treatment. The unwanted psychotropic effects of one of its major components, Δ⁹-tetrahydrocannabinol, discouraged its therapeutic employment until, recently, the discovery of cannabinoids receptors and their endogenous ligands endocannabinoids reignited the interest. The endocannabinoid system has lately been found to play an important role in the maintenance of human health, both centrally and peripherally. However, the initial idea of the endocannabinoid system structure has been quickly understood to be too simplistic and, as new receptors, mediators, and enzymes have been discovered to participate in a complex relationship, the new, more comprehensive term "expanded endocannabinoid system" or "endocannabinoidome", has taken over. The discovery of other endocannabinoid-like receptors, such as the G protein-coupled receptor 119 and G protein-coupled receptor 55, has opened the way to the development of potential therapeutic targets for the treatment of various metabolic disorders. In addition, recent findings have also provided evidence suggesting the potential therapeutic link between the endocannabinoidome and various inflammatory-based gut diseases, such as inflammatory bowel disease and cancer. This review will provide an introduction to the endocannabinoidome, focusing on its modulatory role in the gastrointestinal tract and on the interest generated by the link between gut microbiota, the endocannabinoid system and metabolic diseases such as inflammatory bowel disease, type-2 diabetes and obesity. In addition, we will look at the potential novel aspects and benefits of drugs targeting the endocannabinoid system.

Signaling Targets Related to Antiobesity Effects of Capsaicin: A Scoping Review

The search for new antiobesogenic agents is increasing because of the current obesity pandemic. Capsaicin (Caps), an exogenous agonist of the vanilloid receptor of transient potential type 1 (TRPV1), has shown promising results in the treatment of obesity. This scoping review aims to verify the pathways mediating the effects of Caps in obesity and the different methods adopted to identify these pathways. The search was carried out using data from the EMBASE, MEDLINE (PubMed), Web of Science, and SCOPUS databases. Studies considered eligible evaluated the mechanisms of action of Caps in obesity models or cell types involved in obesity. Nine studies were included and 100% (n = 6) of the in vivo studies showed a high risk of bias. Of the 9 studies, 66.6% (n = 6) administered Caps orally in the diet and 55.5% (n = 5) used a concentration of Caps of 0.01% in the diet. In vitro, the most tested concentration was 1 μM (88.9%; n = 8). Capsazepine was the antagonist chosen by 66.6% (n = 6) of the studies. Seven studies (77.8%) linked the antiobesogenic effects of Caps to TRPV1 activation and 3 (33.3%) indicated peroxisome proliferator-activated receptor (PPAR) involvement as an upstream connection to TRPV1, rather than a direct metabolic target of Caps. The main secondary effects of Caps were lower weight gain (33.3%; n = 3) or loss (22.2%; n = 2), greater improvement in lipid profile (33.3%; n = 3), lower white adipocyte adipogenesis (33.3%; n = 3), browning process activation (44.4%; n = 4), and higher brown adipocyte activity (33.3%; n = 3) compared with those of the control treatment. Some studies have shown that PPAR agonists modulate TRPV1 activity, and no study has evaluated the simultaneous antagonism of these 2 receptors. Consequently, further studies are necessary to elucidate the role of each of these signaling molecules in the antiobesogenic effects of Caps.

TRPV1 channels as a newly identified target for vitamin D

Vitamin D is known to elicit many biological effects in diverse tissue types and is thought to act almost exclusively upon its canonical receptor within the nucleus, leading to gene transcriptional changes and the subsequent cellular response. However, not all the observed effects of vitamin D can be attributed to this sole mechanism, and other cellular targets likely exist but remain to be identified. Our recent discovery that vitamin D is a partial agonist of the Transient Receptor Potential Vanilloid family 1 (TRPV1) channel may provide new insights as to how this important vitamin exerts its biological effects either independently or in addition to the nuclear vitamin D receptor. In this review, we discuss the literature surrounding this apparent discrepancy in vitamin D signaling and compare vitamin D with known TRPV1 ligands with respect to their binding to TRPV1. Furthermore, we provide evidence supporting the notion that this novel vitamin D/TRPV1 axis may explain some of the beneficial actions of this vitamin in disease states where TRPV1 expression and vitamin D deficiency are known to overlap. Finally, we discuss whether vitamin D may also act on other members of the TRP family of ion channels.

WSF-CT-11, a Sesquiterpene Derivative, Activates AMP-Activated Protein Kinase with Anti-diabetic Effects in 3T3-L1 Adipocytes

BACKGROUND

AMP-activated protein kinase (AMPK) is a therapeutic target against type II diabetes (T2D). Synthetic sesquiterpene derivatives were investigated to identify novel AMPK activators as anti-diabetic drugs because the leading drugs like metformin and thiazolidinediones (TZDs) activate AMPK by inhibiting the synthesis of adenosine 5'-triphosphate and thus are associated with some side effects.

RESULTS

We identified WSF-CT-11 as an AMPK activator in HEK293T cells and found that WSF-CT-11 activates AMPK by the activation of transient receptor potential vanilloid type 1 (TRPV1), a Ca²⁺-permeable cation channel. The increased Ca²⁺ influx then activates phosphoinositide 3-kinase (PI3K), protein kinase B (PKB/Akt), and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), which in turn phosphorylates TRPV1 and facilitates the formation of a TRPV1/Akt/CaMKII/AMPK complex. This complex might be important for the regulation of AMPK activity. In 3T3-L1 adipocytes, WSF-CT-11-induced AMPK activation has three anti-diabetic effects. It promotes the assembly of high-molecular-weight adiponectin, which has stronger insulin-sensitizing activity than other multimers. It improves translocation of the glucose transporter type 4, increases glucose uptake, and induces the inhibitory phosphorylation of peroxisome proliferator-activated receptor γ and thus suppresses adipogenesis.

CONCLUSION

WSF-CT-11 is a novel AMPK activator and potential drug against T2D without the side effects of metformin and TZDs.

Transient Receptor Potential Vanilloid Subtype 1: Potential Role in Infection, Susceptibility, Symptoms and Treatment of COVID-19

The battle against the new coronavirus that continues to kill millions of people will be still long. Novel strategies are demanded to control infection, mitigate symptoms and treatment of COVID-19. This is even more imperative given the long sequels that the disease has on the health of the infected. The discovery that S protein includes two ankyrin binding motifs (S-ARBMs) and that the transient receptor potential vanilloid subtype 1 (TRPV-1) cation channels contain these ankyrin repeat domains (TRPs-ARDs) suggest that TRPV-1, the most studied member of the TRPV channel family, can play a role in binding SARS-CoV-2. This hypothesis is strengthened by studies showing that other respiratory viruses bind the TRPV-1 on sensory nerves and epithelial cells in the airways. Furthermore, the pathophysiology in COVID-19 patients is similar to the effects generated by TRPV-1 stimulation. Lastly, treatment with agonists that down-regulate or inactivate TRPV-1 can have a beneficial action on impaired lung functions and clearance of infection. In this review, we explore the role of the TRPV-1 channel in the infection, susceptibility, pathogenesis, and treatment of COVID-19, with the aim of looking at novel strategies to control infection and mitigate symptoms, and trying to translate this knowledge into new preventive and therapeutic interventions.

Vitamin D deficiency promotes accumulation of bioactive lipids and increased endocannabinoid tone in zebrafish

Vitamin D is well known for its traditional role in bone mineral homeostasis; however, recent evidence suggests that vitamin D also plays a significant role in metabolic control. This study served to investigate putative linkages between vitamin D deficiency (VDD) and metabolic disruption of bioactive lipids by MS imaging. Our approach employed infrared-matrix-assisted laser desorption electrospray ionization MS imaging for lipid metabolite profiling in 6-month-old zebrafish fed either a VDD or a vitamin D-sufficient (VDS) diet. Using a lipidomics pipeline, we found that VDD zebrafish had a greater abundance of bioactive lipids (N-acyls, endocannabinoids [ECs], diacylglycerols/triacylglycerols, bile acids/bile alcohols, and vitamin D derivatives) suggestive of increased EC tone compared with VDS zebrafish. Tandem MS was performed on several differentially expressed metabolites with sufficient ion abundances to aid in structural elucidation and provide additional support for MS annotations. To confirm activation of the EC pathways, we subsequently examined expression of genes involved in EC biosynthesis, metabolism, and receptor signaling in adipose tissue and liver from VDD and VDS zebrafish. Gene expression changes were congruent with increased EC tone, with VDD zebrafish demonstrating increased synthesis and metabolism of anandamide compared with VDS zebrafish. Taken together, our data suggest that VDD may promote accumulation of bioactive lipids and increased EC tone in zebrafish.

Effects of Hyperthermia on TRPV1 and TRPV4 Channels Expression and Oxidative Markers in Mouse Brain

Heat stress increases the core body temperature through the pathogenic process. The pathogenic process leads to the release of free radicals, such as superoxide production. Heat stress in the central nervous system (CNS) can cause neuronal damage and symptoms such as delirium, coma, and convulsion. TRPV1 (Transient Receptor Potential Vanilloid1) and TRPV4 genes are members of the TRPV family, including integral membrane proteins that act as calcium-permeable channels. These channels act as thermosensors and have essential roles in the cellular regulation of heat responses. The objective of this study is to examine the effect of general heat stress on the expression of TRPV1 and TRPV4 channels. Furthermore, oxidative markers were measured in the brain of the same heat-stressed mice. Our results show that heat stress leads to a significant upregulation of TRPV1 expression within 21-42 days, while TRPV4 expression decreased significantly in a time-dependent manner. Alterations in the oxidative markers were also observed in the heat-stressed mice.

Estimation of Dietary Capsaicinoid Exposure in Korea and Assessment of Its Health Effects

The consumption of capsaicinoids, the active components in chili peppers, has been associated with both positive and negative health effects, and the level of capsaicinoid exposure may be an important determinant. Dietary capsaicinoid exposure was estimated using a previously developed database for capsaicinoid content and a 24-h dietary recall dataset obtained from the Korea National Health and Nutrition Examination Survey. The estimated consumption level was evaluated to determine its potential effects on weight reduction and gastrointestinal distress. The estimated daily mean capsaicinoid intake was 3.25 mg (2.17 mg capsaicin), and most Koreans consumed 1–30 mg of capsaicinoids (0.67–20 mg capsaicin) in a day. No adverse effect of capsaicin consumption was reported other than abdominal pain. For long-term repeated consumption, 30 mg may be the maximum tolerable dose. However, the effects on body weight or energy balance were inconsistent in 4–12 week clinical studies conducted with various capsaicin doses (2–135 mg), which was likely due to the complex interplay between capsaicin dose, study length, and participant characteristics. Therefore, the capsaicin consumption of most Koreans was below the levels that may cause adverse effects. However, more long-term studies for the dose range of 2–20 mg are required to further characterize capsaicin’s health benefits in Koreans.

Altered Expression of Ion Channels in White Matter Lesions of Progressive Multiple Sclerosis: What Do We Know About Their Function?

Despite significant advances in our understanding of the pathophysiology of multiple sclerosis (MS), knowledge about contribution of individual ion channels to axonal impairment and remyelination failure in progressive MS remains incomplete. Ion channel families play a fundamental role in maintaining white matter (WM) integrity and in regulating WM activities in axons, interstitial neurons, glia, and vascular cells. Recently, transcriptomic studies have considerably increased insight into the gene expression changes that occur in diverse WM lesions and the gene expression fingerprint of specific WM cells associated with secondary progressive MS. Here, we review the ion channel genes encoding K⁺, Ca²⁺, Na⁺, and Cl^- channels; ryanodine receptors; TRP channels; and others that are significantly and uniquely dysregulated in active, chronic active, inactive, remyelinating WM lesions, and normal-appearing WM of secondary progressive MS brain, based on recently published bulk and single-nuclei RNA-sequencing datasets. We discuss the current state of knowledge about the corresponding ion channels and their implication in the MS brain or in experimental models of MS. This comprehensive review suggests that the intense upregulation of voltage-gated Na⁺ channel genes in WM lesions with ongoing tissue damage may reflect the imbalance of Na⁺ homeostasis that is observed in progressive MS brain, while the upregulation of a large number of voltage-gated K⁺ channel genes may be linked to a protective response to limit neuronal excitability. In addition, the altered chloride homeostasis, revealed by the significant downregulation of voltage-gated Cl^- channels in MS lesions, may contribute to an altered inhibitory neurotransmission and increased excitability.

TRP channels in COVID-19 disease: Potential targets for prevention and treatment

Coronavirus disease 2019 [COVID-19] is a global health threat caused by severe acute respiratory syndrome coronavirus 2 [SARS-CoV2] that requires two proteins for entry: angiotensin-converting enzyme 2 [ACE2] and -membrane protease serine 2 [TMPRSS2]. Many patients complain from pneumonia, cough, fever, and gastrointestinal (GI) problems. Notably, different TRP channels are expressed in various tissues infected by SARS-CoV-2. TRP channels are cation channels that show a common architecture with high permeability to calcium [Ca²⁺] in most sub-families. Literature review shed light on the possible role of TRP channels in COVID-19 disease. TRP channels may take part in inflammation, pain, fever, anosmia, ageusia, respiratory, cardiovascular, GI and neurological complications related to COVID-19. Also, TRP channels could be the targets for many active compounds that showed effectiveness against SARS-CoV-2. Desensitization or blocking TRP channels by antibodies, aptamers, small molecules or venoms can be an option for COVID-19 prevention and future treatment. This review provides insights into the involvement of TRP channels in different symptoms and mechanisms of SARS-CoV-2 , potential treatments targeting these channels and highlights missing gaps in literature.

TRPV1 Activation by Capsaicin Mediates Glucose Oxidation and ATP Production Independent of Insulin Signalling in Mouse Skeletal Muscle Cells

BACKGROUND

Insulin resistance (IR), a key characteristic of type 2 diabetes (T2DM), is manifested by decreased insulin-stimulated glucose transport in target tissues. Emerging research has highlighted transient receptor potential cation channel subfamily V member (TRPV1) activation by capsaicin as a potential therapeutic target for these conditions. However, there are limited data on the effects of capsaicin on cell signalling molecules involved in glucose uptake.

METHODS

C2C12 cells were cultured and differentiated to acquire the myotube phenotype. The activation status of signalling molecules involved in glucose metabolism, including 5' adenosine monophosphate-activated protein kinase (AMPK), calcium/calmodulin-dependent protein kinase 2 (CAMKK2), extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), protein kinase B (AKT), and src homology phosphatase 2 (SHP2), was examined. Finally, activation of CAMKK2 and AMPK, and glucose oxidation and ATP levels were measured in capsaicin-treated cells in the presence or absence of TRPV1 antagonist (SB-452533).

RESULTS

Capsaicin activated cell signalling molecules including CAMKK2 and AMPK leading to increased glucose oxidation and ATP generation independent of insulin in the differentiated C2C12 cells. Pharmacological inhibition of TRPV1 diminished the activation of CAMKK2 and AMPK as well as glucose oxidation and ATP production. Moreover, we observed an inhibitory effect of capsaicin in the phosphorylation of ERK1/2 in the mouse myotubes.

CONCLUSION

Our data show that capsaicin-mediated stimulation of TRPV1 in differentiated C2C12 cells leads to activation of CAMKK2 and AMPK, and increased glucose oxidation which is concomitant with an elevation in intracellular ATP level. Further studies of the effect of TRPV1 channel activation by capsaicin on glucose metabolism could provide novel therapeutic utility for the management of IR and T2DM.

Mechanisms linking gut microbial metabolites to insulin resistance

Insulin resistance is the rate-limiting step in the development of metabolic diseases, including type 2 diabetes. The gut microbiota has been implicated in host energy metabolism and metabolic diseases and is recognized as a quantitatively important organelle in host metabolism, as the human gut harbors 10 trillion bacterial cells. Gut microbiota break down various nutrients and produce metabolites that play fundamental roles in host metabolism and aid in the identification of possible therapeutic targets for metabolic diseases. Therefore, understanding the various effects of bacterial metabolites in the development of insulin resistance is critical. Here, we review the mechanisms linking gut microbial metabolites to insulin resistance in various insulin-responsive tissues.

Role and Modulation of TRPV1 in Mammalian Spermatozoa: An Updated Review

Based on the abundance of scientific publications, the polymodal sensor TRPV1 is known as one of the most studied proteins within the TRP channel family. This receptor has been found in numerous cell types from different species as well as in spermatozoa. The present review is focused on analyzing the role played by this important channel in the post-ejaculatory life of spermatozoa, where it has been described to be involved in events such as capacitation, acrosome reaction, calcium trafficking, sperm migration, and fertilization. By performing an exhaustive bibliographic search, this review gathers, for the first time, all the modulators of the TRPV1 function that, to our knowledge, were described to date in different species and cell types. Moreover, all those modulators with a relationship with the reproductive process, either found in the female tract, seminal plasma, or spermatozoa, are presented here. Since the sperm migration through the female reproductive tract is one of the most intriguing and less understood events of the fertilization process, in the present work, chemotaxis, thermotaxis, and rheotaxis guiding mechanisms and their relationship with TRPV1 receptor are deeply analyzed, hypothesizing its (in)direct participation during the sperm migration. Last, TRPV1 is presented as a pharmacological target, with a special focus on humans and some pathologies in mammals strictly related to the male reproductive system.

Potential Interplay between Nrf2, TRPA1, and TRPV1 in Nutrients for the Control of COVID-19

In this article, we propose that differences in COVID-19 morbidity may be associated with transient receptor potential ankyrin 1 (TRPA1) and/or transient receptor potential vanilloid 1 (TRPV1) activation as well as desensitization. TRPA1 and TRPV1 induce inflammation and play a key role in the physiology of almost all organs. They may augment sensory or vagal nerve discharges to evoke pain and several symptoms of COVID-19, including cough, nasal obstruction, vomiting, diarrhea, and, at least partly, sudden and severe loss of smell and taste. TRPA1 can be activated by reactive oxygen species and may therefore be up-regulated in COVID-19. TRPA1 and TRPV1 channels can be activated by pungent compounds including many nuclear factor (erythroid-derived 2) (Nrf2)-interacting foods leading to channel desensitization. Interactions between Nrf2-associated nutrients and TRPA1/TRPV1 may be partly responsible for the severity of some of the COVID-19 symptoms. The regulation by Nrf2 of TRPA1/TRPV1 is still unclear, but suggested from very limited clinical evidence. In COVID-19, it is proposed that rapid desensitization of TRAP1/TRPV1 by some ingredients in foods could reduce symptom severity and provide new therapeutic strategies.

What Role Does the Endocannabinoid System Play in the Pathogenesis of Obesity?

The endocannabinoid system (ECS) is an endogenous signaling system formed by specific receptors (cannabinoid type 1 and type 2 (CB₁ and CB₂)), their endogenous ligands (endocannabinoids), and enzymes involved in their synthesis and degradation. The ECS, centrally and peripherally, is involved in various physiological processes, including regulation of energy balance, promotion of metabolic process, food intake, weight gain, promotion of fat accumulation in adipocytes, and regulation of body homeostasis; thus, its overactivity may be related to obesity. In this review, we try to explain the role of the ECS and the impact of genetic factors on endocannabinoid system modulation in the pathogenesis of obesity, which is a global and civilizational problem affecting the entire world population regardless of age. We also emphasize that the search for potential new targets for health assessment, treatment, and the development of possible therapies in obesity is of great importance.