Blood biomarkers, including neurofilament light chain (NfL), have garnered attention as potential indicators for chemotherapy-induced peripheral neuropathy (CIPN), a dose-limiting adverse effect of neurotoxic anticancer drugs. However, no blood biomarker has been established for routine application or translational research. This pilot study aimed to evaluate a limited panel of blood biomarkers in rat models of CIPN and their correlations with neuropathic pain. CIPN models were induced through repeated injections of oxaliplatin, paclitaxel, bortezomib, and vincristine. Electronic von Frey testing was used to assess tactile allodynia. Post anticancer injections, serum concentrations of 31 proteins were measured. Allodynia thresholds decreased in anticancer-treated animals compared to controls. No consistent modifications were observed in the biomarkers across CIPN models. The most noteworthy biomarkers with increased concentrations in at least two CIPN models were NfL (paclitaxel, vincristine), MCP-1, and RANTES (oxaliplatin, vincristine). Vincristine-treated animals exhibited strong correlations between LIX, MCP-1, NfL, and VEGF concentrations and tactile allodynia thresholds. No single biomarker can be recommended as a unique indicator of CIPN-related pain. Because of the study limitations (single dose of each anticancer drug, young animals, and single time measurement of biomarkers), further investigations are necessary to define the kinetics, specificities, and sensitivities of MCP-1, RANTES, and NfL.

The Western diet, rich in lipids and in n-6 polyunsaturated fatty acids (PUFAs), favors gut dysbiosis observed in Crohn’s disease (CD). The aim of this study was to assess the effects of rebalancing the n-6/n-3 PUFA ratio in CEABAC10 transgenic mice that mimic CD. Mice in individual cages with running wheels were randomized in three diet groups for 12 weeks: high-fat diet (HFD), HFD + linseed oil (HFD-LS-O) and HFD + extruded linseed (HFD-LS-E). Then, they were orally challenged once with the Adherent-Invasive Escherichia coli (AIEC) LF82 pathobiont. After 12 weeks of diet, total energy intake, body composition, and intestinal permeability were not different between groups. After the AIEC-induced intestinal inflammation, fecal lipocalin-2 concentration was lower at day 6 in n-3 PUFAs supplementation groups (HFD-LS-O and HFD-LS-E) compared to HFD. Analysis of the mucosa-associated microbiota showed that the abundance of Prevotella, Paraprevotella, Ruminococcus, and Clostridiales was higher in the HFD-LS-E group. Butyrate levels were higher in the HFD-LS-E group and correlated with the Firmicutes/Proteobacteria ratio. This study demonstrates that extruded linseed supplementation had a beneficial health effect in a physically active mouse model of CD susceptibility. Additional studies are required to better decipher the matrix influence in the linseed supplementation effect.

Obesity and prediabetes are the two strongest risk factors of type 2 diabetes. It has been reported that TOTUM-63, a polyphenol-rich plant extract, has beneficial effects on body weight (BW) and insulin resistance in mice fed a high fat diet (HFD). The study aim was to determine whether high-intensity interval training (HIIT) and/or TOTUM-63 supplementation improved body composition and glycemic control and gut microbiota composition in a Western diet-induced obesity rat model. Wistar rats received a standard diet (CTRL; control; n = 12) or HFD (HFD; n = 48) for 16 weeks. Then, HFD rats were divided in four groups: HFD, HFD + TOTUM-63 (T63), HFD + HIIT (HIIT), and HFD + HIIT +T63 (HIIT + T63). Training was performed 4 days/week for 12 weeks. TOTUM-63 was included in diet composition (2%). The HIIT + T63 combination significantly limited BW gain, without any energy intake modulation, and improved glycemic control. BW variation was correlated with increased α-diversity of the colon mucosa microbiota in the HIIT + T63 group. Moreover, the relative abundance of Anaeroplasma, Christensenellaceae and Oscillospira was higher in the HIIT + T63 group. Altogether, these results suggest that the HIIT and TOTUM-63 combination could be proposed for the management of obesity and prediabetes.

Obesity, a major public health problem, is the consequence of an excess of body fat and biological alterations in the adipose tissue. Our aim was to determine whether high-intensity interval training (HIIT) and/or α-linolenic acid supplementation (to equilibrate the n-6/n-3 polyunsaturated fatty acids (PUFA) ratio) might prevent obesity disorders, particularly by modulating the mucosa-associated microbiota. Wistar rats received a low fat diet (LFD; control) or high fat diet (HFD) for 16 weeks to induce obesity. Then, animals in the HFD group were divided in four groups: HFD (control), HFD + linseed oil (LO), HFD + HIIT, HFD + HIIT + LO. In the HIIT groups, rats ran on a treadmill, 4 days.week−1. Erythrocyte n-3 PUFA content, body composition, inflammation, and intestinal mucosa-associated microbiota composition were assessed after 12 weeks. LO supplementation enhanced α-linolenic acid (ALA) to docosahexaenoic acid (DHA) conversion in erythrocytes, and HIIT potentiated this conversion. Compared with HFD, HIIT limited weight gain, fat mass accumulation, and adipocyte size, whereas LO reduced systemic inflammation. HIIT had the main effect on gut microbiota β-diversity, but the HIIT + LO association significantly increased Oscillospira relative abundance. In our conditions, HIIT had a major effect on body fat mass, whereas HIIT + LO improved ALA conversion to DHA and increased the abundance of Oscillospira bacteria in the microbiota.

Recent studies have revealed gender differences in cold perception, and pointed to a possible direct action of testosterone (TST) on the cold-activated TRPM8 (Transient Receptor Potential Melastatin Member 8) channel. However, the mechanisms by which TST influences TRPM8-mediated sensory functions remain elusive. Here, we show that TST inhibits TRPM8-mediated mild-cold perception through the noncanonical engagement of the Androgen Receptor (AR). Castration of both male rats and mice increases sensitivity to mild cold, and this effect depends on the presence of intact TRPM8 and AR. TST in nanomolar concentrations suppresses whole-cell TRPM8-mediated currents and single-channel activity in native dorsal root ganglion (DRG) neurons and HEK293 cells co-expressing recombinant TRPM8 and AR, but not TRPM8 alone. AR cloned from rat DRGs shows no difference from standard AR. However, biochemical assays and confocal imaging reveal the presence of AR on the cell surface and its interaction with TRPM8 in response to TST, leading to an inhibition of channel activity.

BACKGROUND AND AIM:Exercise is an effective strategy to reduce obesity-induced oxidative stress. The purpose of this study was to compare the effects of two training modalities (moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT)) on the pro/antioxidant status of different tissues in obese Zucker rats.METHODS:Eight-week-old male Zucker rats (fa/fa, n = 36) were subdivided in three groups: MICT, HIIT, and control (no exercise) groups. Trained animals ran on a treadmill (0° slope), 5 days/week for 10 weeks (MICT: 51 min at 12 m·min-1; HIIT: 6 sets of 3 min at 10 m·min-1 followed by 4 min at 18 m·min-1). Epididymal (visceral) and subcutaneous adipose tissue, gastrocnemius muscle, and plasma samples were collected to measure oxidative stress markers (advanced oxidation protein products (AOPP), oxidized low-density lipoprotein (oxLDL)), antioxidant system markers (ferric-reducing ability of plasma (FRAP), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) activities), and prooxidant enzymes (NADPH oxidase and xanthine oxidase (XO) activities, myeloperoxidase content).RESULTS:Compared with the control, MICT increased GPx and catalase activities and the FRAP level in epididymal adipose tissue. HIIT increased the AOPP level in subcutaneous adipose tissue. In the muscle, HIIT increased both SOD and GPx activities and reduced the AOPP level, whereas MICT increased only SOD activity. Finally, plasma myeloperoxidase content was similarly decreased by both training modalities, whereas oxLDL was reduced only in the MICT group.CONCLUSION:Both HIIT and MICT improved the pro/antioxidant status. However, HIIT was more efficient than MICT in the skeletal muscle, whereas MICT was more efficient in epididymal adipose tissue. This suggests that oxidative stress responses to HIIT and MICT are tissue-specific. This could result in ROS generation via different pathways in these tissues. From a practical point of view, the two training modalities should be combined to obtain a global response in people with obesity.

Context:Neuregulin 1 (NRG1) and ErbB receptors are involved in glucose homeostasis. However, the effects of the neuregulin 1-ErbB pathway activation on glucose metabolism in liver are controversial. Objective:Assess NRG1 and ErbB signalling in liver and the effects of 8-week treatment with NRG1 on glucose homeostasis in diabetic db/db mice and in control healthy mice. Results:NRG1 improved glucose, insulin and insulin sensitivity index during OGTT in db/db mice, but not in control mice. Compared with healthy mice, phosphorylation of p38, ErbB-1 and ErbB-3 was increased in diabetic mice, and neuregulin 1 treatment increased phosphorylation of p38 and ErbB-4. Conversely, the AKT/FOXO1 pathway was not affected by the 8-week treatment with NRG1. Conclusion:Diabetic mice showed altered NRG1-ErbB pathway in the liver compared with healthy mice. Moreover, chronic NRG1 treatment increased p38 phosphorylation in liver and improved glucose tolerance in diabetic mice, but not in control mice.

Chronic pain is associated with anxiety and depression episodes. The amygdala plays a key role in the relationship between emotional responses and chronic pain. Here, we investigated the role of Acid-Sensing Ion Channels 1a within the basolateral amygdala (BLA), in pain and associated anxiety in a rat model of monoarthritis (MoAr). Administration within the BLA of PcTx1 or mambalgin-1, two specific inhibitors of ASIC1a-containing channels significantly inhibited pain and anxiety-related behaviours in MoAr rats. The effect of PcTx1 was correlated with a reduction of c-Fos expression in the BLA. We examined the expression profile of ASICs and other genes in the amygdala in MoAr and sham animals, and found no variation of the expression of ASIC1a, which was confirmed at the protein level. However, an increase in the BLA of MoAr rats of both PI3Kinase mRNA and the phosphorylated form of Akt, along with Bdnf mRNA, suggest that the BDNF/PI3-kinase/Akt pathway might regulate ASIC1a in BLA neurons as demonstrated in spinal sensitisation phenomenon. We also observed changes in several kinase mRNAs expression (PICK1, Sgk1) that are potentially involved in ASIC1a regulation. These results show a crucial role of ASIC1a channels in the BLA in pain and anxiety-related behaviours during arthritis.

It has been reported that neuregulin1 (NRG1) improves glucose tolerance in healthy and diabetic rodents. In vitro studies also suggest that NRG1 regulates myocyte oxidative capacity. To confirm this observation in vivo , we evaluated the effect on mitochondrial function of an 8-week treatment with NRG1 in db/db diabetic mice and C57BL/6JRJ healthy controls. NRG1 treatment improved complex 2-mediated mitochondrial respiration in the gastrocnemius of both control and diabetic mice and increased mitochondrial complex 2 subunit content by 2-fold. This effect was not associated with an increase in mitochondrial biogenesis markers. Enhanced ERBB4 phosphorylation could mediate NRG1 effects on mitochondrial function through signalling pathways, independently of ERK1/2, AKT or AMPK.

Background and aims Previous studies from our laboratory had shown that neuregulin‐1 (NRG1) has a role in glucose homeostasis, improving glucose tolerance in db/db mice. A predominant role of the liver has been suggested, since NRG1 receptors were activated only in the hepatic tissue, but not in skeletal muscle or adipose tissue. Our aim was to study whole body insulin sensitivity and hepatic response to an acute treatment with NRG1. Methods Three hour fasted 9‐week old db/db mice were injected with NRG1 (50μg/kg) or saline (SAL) as control. After 2h, a hyperinsulinemic‐euglycemic clamp was performed. A different group under the same conditions, was used to study hepatic signalling after the NRG1 or SAL injection. Results Two hours after injection, insulin levels were lower in db/db mice injected with NRG1 (38±9 SAL vs 18±4 NRG1, ng/ml). As consequence, this group of mice showed lower glucose infusion rate (GIR) during the clamp (21±2 SAL vs 13±3 NRG1, mg/kg·min). Despite lower insulin levels, glucose turnover (Rd) and hepatic glucose production (endo‐Ra) were significantly decreased in the presence of NRG1 (Rd: 32±3 SAL vs 24±2 NRG1, mg/kg·min. EndoRa: 10±1 SAL vs 7±1 NRG1, p<0.05; mg/kg·min). Tissue‐specific glucose uptake was not different. Liver Akt phosphorylation (Ser 473) ratio was significantly higher in db/db mice 2h after NRG1 treatment (1±0.4 SAL vs 4.5±0.9 NRG1, p<0.05, arbitrary units). GSK3‐β phosphorylation (Ser9) ratio was not different. Hepatic gene expression of G6pc was lower in db/db mice treated with NRG1 (Rq 1±0.03 SAL vs 0.6±0.1 NRG1). Hepatic glycogen content was not different among groups. Conclusions Acute (2h) treatment with neuregulin‐1 caused a decrease in insulin levels, glucose turnover, and hepatic glucose production during the hyperinsulinemic‐euglycemic clamp. The stronger inhibition in endo‐Ra with lower insulin levels, may reflect an increase in hepatic insulin sensitivity and/or a direct effect of NRG1 on hepatic glucose production. The increased Akt phosphorylation ratio and decreased G6pc gene expression could be involved in the mechanism used by NRG1. Support or Funding Information This work has been supported by a grant from Université Blaise Pascal.

PURPOSE: Neuregulin 1 (NRG1) is involved in the regulation of glucose metabolism in rodent skeletal muscle. We hypothesized that metabolic disorders could be associated with alterations of the NRG1 signaling pathway and that chronic endurance exercise could improve NRG1 signaling in rat skeletal muscle. METHODS: Male Wistar rats were fed a high fat/high sucrose (HF/HS) diet for 16 weeks. At the end of this period, NRG1 and ErbB expression/activity were assessed in skeletal muscle of obese rat suffering from glucose intolerance induced by the HF/HS diet and compared to controls (nonobese, well-balanced diet). Then, the obese rats continued the HF/HS diet without or with endurance exercise training (5 times/week) or were switched to a well-balanced diet without or with exercise training for another 8 weeks and NRG1 and ErbB expression/activity in skeletal muscle were tested again. RESULTS: First, we found that a 16-week HF/HS diet induced obesity, but did not significantly affect the NRG1/ErbB signaling pathway in rat skeletal muscle. Conversely, after HF/HS obese rats were switched to a well-balanced diet with endurance exercise training for 8 weeks, NRG1 cleavage ratio in skeletal muscle was increased by 3-fold and ErbB4 phosphorylation by 1.7-fold compared to control animals (HF/HS diet, without intervention). This was associated with increased protein expression and phosphorylation ratio of the metalloprotease ADAM17, which is involved in NRG1 shedding. Well-balanced diet or physical exercise alone did not induce these effects, demonstrating a synergistic effect of these interventions. Similarly, in vitro stretch-induced activation of ADAM17 in rat myoblasts induced NRG1 cleavage and ErbB4 activation. CONCLUSIONS: These results showed that endurance training combined with a well-balanced diet activates the NRG1-ErbB4 pathway in skeletal muscle of obese rats. This effect, possibly through ADAM17-mediated cleavage of NRG1, might improve the cell carbohydrate metabolism in metabolic disorders. Supported by the Heart and Arteries Foundation (Fondation Coeur et Artères).

Some studies suggest that neuregulin 1 (NRG1) could be involved in the regulation of skeletal muscle energy metabolism in rodents. Here we assessed whether unbalanced diet is associated with alterations of the NRG1 signalling pathway and whether exercise and diet might restore NRG1 signalling in skeletal muscle of obese rats. We show that diet-induced obesity does not impair NRG1 signalling in rat skeletal muscle. We also report that endurance training and a well-balanced diet activate the NRG1 signalling in skeletal muscle of obese rats, possibly via a new mechanism mediated by the protease ADAM17. These results suggest that some beneficial effects of physical activity and diet in obese rats could be partly explained by stimulation of the NRG1 signalling pathway.Some studies suggest that the signalling pathway of neuregulin 1 (NRG1), a protein involved in the regulation of skeletal muscle metabolism, could be altered by nutritional and exercise interventions. We hypothesized that diet-induced obesity could lead to alterations of the NRG1 signalling pathway and that chronic exercise could improve NRG1 signalling in rat skeletal muscle. To test this hypothesis, male Wistar rats received a high fat/high sucrose (HF/HS) diet for 16weeks. At the end of this period, NRG1 and ErbB expression/activity in skeletal muscle was assessed. The obese rats then continued the HF/HS diet or were switched to a well-balanced diet. Moreover, in both groups, half of the animals also performed low intensity treadmill exercise training. After another 8weeks, NRG1 and ErbB expression/activity in skeletal muscle were tested again. The 16week HF/HS diet induced obesity, but did not significantly affect the NRG1/ErbB signalling pathway in rat skeletal muscle. Conversely, after the switch to a well-balanced diet, NRG1 cleavage ratio and ErbB4 amount were increased. Chronic exercise training also promoted NRG1 cleavage, resulting in increased ErbB4 phosphorylation. This result was associated with increased protein expression and phosphorylation ratio of the metalloprotease ADAM17, which is involved in NRG1 shedding. Similarly, in vitro stretch-induced activation of ADAM17 in rat myoblasts induced NRG1 cleavage and ErbB4 activation. These results show that low intensity endurance training and well-balanced diet activate the NRG1-ErbB4 pathway, possibly via the metalloprotease ADAM17, in skeletal muscle of diet-induced obese rats.

In vitro experiments using rodent skeletal muscle cells suggest that neuregulin 1 (NRG1) is involved in glucose metabolism regulation, although no study has evaluated the role of NRG1 in systemic glucose homeostasis. The purpose of this study was to investigate the effect of chronic and acute NRG1 treatment on glucose homeostasis in db/db mice. To this aim, glucose tolerance tests were performed in 8-week-old male db/db mice after treatment with NRG1 (50μg.kg-1) or saline 3 times per week for 8 weeks. In other experiments, glucose tolerance and pyruvate tolerance tests were performed in db/db mice 15 minutes after a single NRG1 (50μg.kg-1) or saline injection. Liver, adipose tissue, hypothalamus and skeletal muscle were also collected 30 minutes after acute NRG1 (50μg.kg-1) or saline treatment, and the phosphorylation status of the ERBB receptors, AKT (on Ser473) and FOXO1 (on Ser256) was assessed by western blotting. Chronic treatment (8 weeks) with NRG1 improved glucose tolerance in db/db mice. Acute treatment also lowered glycemia and insulinemia during glucose or pyruvate tolerance tests. NRG1 acute injection induced activation of ERBB3 receptors and phosphorylation of AKT and FOXO1 only in liver. Altogether, this study shows that acute and chronic NRG1 treatments improve glucose tolerance in db/db mice. This effect could be mediated through inhibition of hepatic gluconeogenesis.

This study determined, using the intraarticular complete Freund adjuvant arthritis mice model, whether the radiotracer Tc-99m-N-(triethyl-ammonium)- 3-propyl-[15] ane-N5 ((99)mTc-NTP 15-5) targeting proteoglycans has a pathophysiologic validity for in vivo imaging of rheumatoid arthritis (RA) and its response to chronic nonsteroidal antiinflammatory drugs. Methods: We investigated the time course of cartilage remodeling by Tc-99m-NTP 15-5 scintigraphy, bone damages by Tc-99m-hydroxymethylene diphosphonate imaging, inflammation by F-18-FDG PET, and joint proteoglycan content and pain behavior in animals, without and with meloxicam treatment. Paw circumference, thermal pain behavior, and histology as well as proteoglycan content of the whole joint were determined. Results: Tc-99m-NTP 15-5 showed specific tracer accumulation within RA joints, with a significant increase in scintigraphic ratio observed in RA versus shams from day 3 to day 28. F-18-FDG evidenced uptake in RA joints from day 15 to day 29. Animals treated with meloxicam (5 mg/kg) exhibited a dose-dependent decrease in both Tc-99m-NTP 15-5 and F-18-FDG uptake ratios versus saline-treated animals. Tc-99m-hydroxymethylene diphosphonate bone scans were only positive at day 14 in RA versus shams, with a significant effect of meloxicam. An increase in proteoglycans of RA joint and thermal pain behavior were observed and were dose-dependently reduced by meloxicam. Conclusion: These experimental results bring data in favor of the Tc-99m-NTP 15-5 radiotracer for assessing, in vivo, cartilage remodeling in RA that could be used to monitor therapy.

Chronic pain is a multidimensional experience that not only includes changes in nociception but also impairments in emotional and cognitive functions, not often taken into account in preclinical research. The present study investigated emotional and cognitive impairments in an animal model of persistent inflammatory pain as well as the involvement of the basolateral complex (BLC) of the amygdala in these components. Monoarthritis was induced by intra-articular injection of complete Freund׳s adjuvant. Mechanical hypersensitivity, anxiety and depressive-like behaviours as well as cognitive capacities were assessed using several tests, such as von Frey, social interaction, open field, saccharin preference, spatial and social recognition memory tests. The effects of morphine administered systemically or into the BLC of the amygdala were also studied. Monoarthritic rats exhibited mechanical hypersensitivity, anxiety and depressive-like behaviours as well as cognitive impairments. Whereas low systemic doses and intra-BLC infusion of morphine failed to reduce mechanical hypersensitivity, they reversed monoarthritis-induced anxiety-like behaviours and cognitive impairments. Our findings further support a crucial role of amygdala in the effect of morphine on emotional/cognitive components of pain and not on mechanical hypersensitivity. Finally, our study highlights the interest of a multi-behavioural approach in the assessment of pain and the analgesic effect of drugs.