Opioid infusions at different times of the day produce varying degrees of opioid-induced hyperalgesia.

BACKGROUND: Opioids are metabolised by enzymes the activities of which vary with the circadian rhythm. We examined whether opioid infusions administered at different times of the day produce varying degrees of opioid-induced hyperalgesia (OIH) in animal experiments and clinical studies. METHODS: Male Sprague-Dawley rats received remifentanil infusions (1 µg kg-1·min-1 for 1 h) at Zeitgeber times (ZT) 0, 4, 8, 12, 16, or 20 h. Rhythmicity of mechanical hypersensitivity was assayed after the infusion. Mechanical hypersensitivity, drug concentration, and metabolic enzyme activity of Wistar rats that received sufentanil (10 µg kg-1; four consecutive i.p. injections at 15-min intervals) or remifentanil infusion at ZT0 or ZT8 were assayed. Sixty patients who underwent abdominal laparoscopic surgery under general anaesthesia received remifentanil infusion (0.15 µg kg-1 min-1) and sufentanil injection (0.2 µg kg-1) at induction and skin incision, respectively. Postoperative pressure pain sensitivity, pain Numeric Rating Scale (NRS), drug concentrations, and nonspecific esterase activity were assessed. RESULTS: Sprague-Dawley rats that received remifentanil infusion exhibited a robust rhythmic paw withdrawal threshold (JTK_CYCLE: P=0.001, Q=0.001, Phase=26). Wistar rats infused with remifentanil or sufentanil at ZT8 exhibited greater OIH (P<0.001) than those infused at ZT0, with higher blood concentrations (P<0.001) and lower metabolic enzyme activities (P=0.026 and P=0.028, respectively). Patients in the afternoon group exhibited higher pressure pain sensitivity at forearm (P=0.002), higher NRS (P<0.05), higher drug concentrations (sufentanil: P=0.037, remifentanil: P=0.005), and lower nonspecific esterase activity (P=0.024) than the morning group. CONCLUSIONS: Opioid infusions administered at different times of day produced varying degrees of OIH, possibly related to circadian rhythms of metabolic enzyme activities. CLINICAL TRIAL REGISTRATION: NCT05234697.

A signalling pathway for transcriptional regulation of sleep amount in mice.

In mice and humans, sleep quantity is governed by genetic factors and exhibits age-dependent variation1-3. However, the core molecular pathways and effector mechanisms that regulate sleep duration in mammals remain unclear. Here, we characterize a major signalling pathway for the transcriptional regulation of sleep in mice using adeno-associated virus-mediated somatic genetics analysis4. Chimeric knockout of LKB1 kinase-an activator of AMPK-related protein kinase SIK35-7-in adult mouse brain markedly reduces the amount and delta power-a measure of sleep depth-of non-rapid eye movement sleep (NREMS). Downstream of the LKB1-SIK3 pathway, gain or loss-of-function of the histone deacetylases HDAC4 and HDAC5 in adult brain neurons causes bidirectional changes of NREMS amount and delta power. Moreover, phosphorylation of HDAC4 and HDAC5 is associated with increased sleep need, and HDAC4 specifically regulates NREMS amount in posterior hypothalamus. Genetic and transcriptomic studies reveal that HDAC4 cooperates with CREB in both transcriptional and sleep regulation. These findings introduce the concept of signalling pathways targeting transcription modulators to regulate daily sleep amount and demonstrate the power of somatic genetics in mouse sleep research.

Chemical perturbations reveal that RUVBL2 regulates the circadian phase in mammals.

Transcriptional regulation lies at the core of the circadian clockwork, but how the clock-related transcription machinery controls the circadian phase is not understood. Here, we show both in human cells and in mice that RuvB-like ATPase 2 (RUVBL2) interacts with other known clock proteins on chromatin to regulate the circadian phase. Pharmacological perturbation of RUVBL2 with the adenosine analog compound cordycepin resulted in a rapid-onset 12-hour clock phase-shift phenotype at human cell, mouse tissue, and whole-animal live imaging levels. Using simple peripheral injection treatment, we found that cordycepin penetrated the blood-brain barrier and caused rapid entrainment of the circadian phase, facilitating reduced duration of recovery in a mouse jet-lag model. We solved a crystal structure for human RUVBL2 in complex with a physiological metabolite of cordycepin, and biochemical assays showed that cordycepin treatment caused disassembly of an interaction between RUVBL2 and the core clock component BMAL1. Moreover, we showed with spike-in ChIP-seq analysis and binding assays that cordycepin treatment caused disassembly of the circadian super-complex, which normally resides at E-box chromatin loci such as PER1, PER2, DBP, and NR1D1 Mathematical modeling supported that the observed type 0 phase shifts resulted from derepression of E-box clock gene transcription.

Identification of entacapone as a chemical inhibitor of FTO mediating metabolic regulation through FOXO1.

Recent studies have established the involvement of the fat mass and obesity-associated gene (FTO) in metabolic disorders such as obesity and diabetes. However, the precise molecular mechanism by which FTO regulates metabolism remains unknown. Here, we used a structure-based virtual screening of U.S. Food and Drug Administration-approved drugs to identify entacapone as a potential FTO inhibitor. Using structural and biochemical studies, we showed that entacapone directly bound to FTO and inhibited FTO activity in vitro. Furthermore, entacapone administration reduced body weight and lowered fasting blood glucose concentrations in diet-induced obese mice. We identified the transcription factor forkhead box protein O1 (FOXO1) mRNA as a direct substrate of FTO, and demonstrated that entacapone elicited its effects on gluconeogenesis in the liver and thermogenesis in adipose tissues in mice by acting on an FTO-FOXO1 regulatory axis.

BMI1 and MEL18 Promote Colitis-Associated Cancer in Mice via REG3B and STAT3.

BACKGROUND & AIMS: Polycomb group proteins are epigenetic factors that silence gene expression; they are dysregulated in cancer cells and contribute to carcinogenesis by unclear mechanisms. We investigated whether BMI1 proto-oncogene, polycomb ring finger (BMI1), and polycomb group ring finger 2 (PCGF2, also called MEL18) are involved in the initiation and progression of colitis-associated cancer (CAC) in mice. METHODS: We generated mice containing floxed alleles of Bmi1 and/or Mel18 and/or Reg3b using the villin-Cre promoter (called Bmi1ΔIEC, Mel18ΔIEC, DKO, and TKO mice). We also disrupted Bmi1 and/or Mel18 specifically in intestinal epithelial cells (IECs) using the villin-CreERT2-inducible promoter. CAC was induced in cre-negative littermate mice (control) and mice with conditional disruption of Bmi1 and/or Mel18 by intraperitoneal injection of azoxymethane (AOM) followed by addition of dextran sulfate sodium (DSS) to drinking water. Colon tissues were collected from mice and analyzed by histology and immunoblots; IECs were isolated and used in cDNA microarray analyses. RESULTS: Following administration of AOM and DSS, DKO mice developed significantly fewer polyps than control, Bmi1ΔIEC, Mel18ΔIEC, Reg3bΔIEC, or TKO mice. Adenomas in the colons of DKO mice were low-grade dysplasias, whereas adenomas in control, Bmi1ΔIEC, Mel18ΔIEC, Reg3bΔIEC, or TKO mice were high-grade dysplasias with aggressive invasion of the muscularis mucosa. Disruption of Bmi1 and Mel18 (DKO mice) during late stages of carcinogenesis significantly reduced the numbers of large adenomas and the load of total adenomas, reduced proliferation, and increased apoptosis in colon tissues. IECs isolated from DKO mice after AOM and DSS administration had increased expression of Reg3b compared with control, Bmi1ΔIEC, or Mel18ΔIEC mice. Expression of REG3B was sufficient to inhibit cytokine-induced activation of STAT3 in IECs. The human REG3ß protein, the functional counterpart of mouse REG3B, inhibited STAT3 activity in human 293T cells, and its expression level in colorectal tumors correlated inversely with pSTAT3 level and survival times of patients. CONCLUSIONS: BMI1 and MEL18 contribute to the development of CAC in mice by promoting proliferation and reducing apoptosis via suppressing expression of Reg3b. REG3B negatively regulates cytokine-induced activation of STAT3 in colon epithelial cells. This pathway might be targeted in patients with colitis to reduce carcinogenesis.

A Central Catecholaminergic Circuit Controls Blood Glucose Levels during Stress.

Stress-induced hyperglycemia is a fundamental adaptive response that mobilizes energy stores in response to threats. Here, our examination of the contributions of the central catecholaminergic (CA) neuronal system to this adaptive response revealed that CA neurons in the ventrolateral medulla (VLM) control stress-induced hyperglycemia. Ablation of VLM CA neurons abolished the hyperglycemic response to both physical and psychological stress, whereas chemogenetic activation of these neurons was sufficient to induce hyperglycemia. We further found that CA neurons in the rostral VLM, but not those in the caudal VLM, cause hyperglycemia via descending projections to the spinal cord. Monosynaptic tracing experiments showed that VLM CA neurons receive direct inputs from multiple stress-responsive brain areas. Optogenetic studies identified an excitatory PVN-VLM circuit that induces hyperglycemia. This study establishes the central role of VLM CA neurons in stress-induced hyperglycemia and substantially expands our understanding of the central mechanism that controls glucose metabolism.

Estrogen related receptor α-induced adipogenesis is PGC-1ß-dependent.

Previous report showed that Estrogen related receptor α (ERRα) knockout mice had a significant reduction in adipose tissue deposition. Although it was reported that ERRα could promote adipogenesis in several immortalized preadipocytes cell lines, the mechanism behind which is still unclear to date. Besides, the expression pattern of ERRα in white adipose tissue is rarely examined. Here, we show that the expression of ERRα in primary cultured adipocytes is closely associated with adipogenesis. Besides, we found that peroxisome proliferator-activated receptor-γ coactivator 1ß (PGC-1ß) play an important role in regulating ERRα-induced adipogenesis. ERRα-induced adipogenesis was greatly attenuated when knocking down PGC-1ß expression, while rescued by overexpression of PGC-1ß. However, PGC-1ß could still promote adipogenesis when suppressing ERRα expression. Furthermore, we demonstrated that ERRα could transcriptionally active PGC-1ß expression and then enhance the formation of sterol-regulatory-element-binding protein-1c (SREBP-1c)/PGC-1ß complex and peroxisome proliferator-activated receptor-γ (PPARγ)/PGC-1ß complex. Taken together, these results indicate that ERRα-induced adipogenesis is triggered by modulating the expression of PGC-1ß.

[Role of estrogen-related receptor alpha in adipocyes lipolysis].

Estrogen-related receptor a (ERRalpha) is a key regulator for energy metabolism and adipogenesis. However, its role in lipolysis is unknown. To study the function of ERRalpha in lipolysis, primary cultured differentiated porcine adipocytes were treated by a specific inverse agonist XCT790 or infected with adenoviral vector expressed ERRalpha for 48 h, in the absence and/or presence of specific protein kinase A (PKA) inhibitor or extracellular signal-related kinase (ERK) inhibitor. Then, we measured the triglyceride (TG) content and the glycerol release into the culture media to analysis the effect of ERRalpha on lipolysis; Further, we analyzed the expression of PPARgamma, perilipin A, p-perilipin A, HSL and ATGL with Western blotting. Here, we found that ERRalpha significantly increased adipocytes differentiation, TG accumulation and glycerol release. Separately or simultaneously block the PKA and ERK pathway do not significantly altered the effect of ERRalpha on glycerol release. ERRalpha significantly up-regulated the proteins expression of PPARgamma, perilipin A, HSL and ATGL, while the p-perilipin A protein level was not significantly changed. These findings imply that ERRalpha could increase lipolysis via up-regulating HSL and ATGL, thereby to supply more FFA as substrate for a larger turnover of cellular triglyceride pool during adipocytes differentiation.

[Cloning, expression of the porcine estrogen-related receptor alpha gene and its effect on lipid accumulation in mature adipocytes].

Estrogen-related receptor alpha (ERR alpha) is an orphan nuclear receptor and functions as a key regulator of energy metabolism in high energy demand tissues. However, its role in white adipose tissue is largely unknown. In this study, we aim to clone the ORF sequence of pig ERR alpha with touch down-PCR, analyze the expression pattern of ERR alpha protein and its subcellular localization with Western blotting and cell immunofluorescence method respectively, and identify the effect of ERR alpha on lipid accumulation in mature porcine adipocytes with its specific inhibitor XCT790. The results showed that the ERR alpha ORF sequence is 1269 bp (GenBank Accession No. FJ446485, not published), and encode 422 amino acids. The homologies of ERR alpha nucleotide and amino acids sequences are high in different species. ERR alpha protein is highly expressed in pig white adipose tissue, kidney and heart, while remarkably lower in spleen. Cell immunofluorescence results indicated that ERR alpha protein distribute widely in adipocytes nucleus and cytoplasm. XCT790 significantly inhibited the expression of ERR alpha and lipid accumulation in porcine mature adipocyte. This study will provide new target and theoretical reference for fat deposition control.

Interleukin-6 stimulates lipolysis in porcine adipocytes.

Interleukin (IL)-6 stimulates lipolysis in human and rodents adipocytes. However, the mechanism regulating this process is little known. In this study, we demonstrated that IL-6 increased lipolysis in differentiated porcine adipocytes by activation of extracellular signal-related kinase (ERK), which was inhibited by specific ERK inhibitor PD98059. IL-6 treatment did not elevate intracellular cAMP and specific PKA inhibitor H89 did not affect IL-6-induced lipolysis, which suggested that protein kinase A (PKA) pathway was not involved in IL-6-induced lipolysis. Also, the expressions of perilipin A and PPARgamma2 were significantly reduced in response to IL-6 treatment, but the expressions of peroxisome proliferators-activated receptor gamma coactivator-1 alpha (PGC-1alpha), carnitinepalmitoyl-transferase-1 (CPT-1), and uncoupling protein 2 (UCP2) were significantly elevated. In conclusion, these results suggested that chronic high dose of IL-6 directly stimulated lipolysis in porcine adipocytes through activation of ERK, subsequently repressing perilipin A and promoting PGC-1alpha expression.