Renogrit attenuates Vancomycin-induced nephrotoxicity in human renal spheroids and in Sprague-Dawley rats by regulating kidney injury biomarkers and creatinine/urea clearance.

Vancomycin, is widely used against methicillin-resistant bacterial infections. However, Vancomycin accumulation causes nephrotoxicity which leads to an impairment in the filtration mechanisms of kidney. Traditional herbal medicines hold potential for treatment of drug-induced nephrotoxicity. Herein, we investigated protective properties of plant-based medicine Renogrit against Vancomycin-induced kidney injury. Phytometabolite analysis of Renogrit was performed by UHPLC. Spheroids formed from human proximal tubular cell (HK-2) were used for in vitro evaluation of Vancomycin-induced alterations in cell viability, P-gp functionality, NAG, KIM-1 levels, and mRNA expression of NGAL and MMP-7. The in vivo efficacy of Renogrit against Vancomycin-induced nephrotoxicity was further evaluated in Sprague-Dawley (SD) rats by measurement of BUN, serum creatinine, and their respective clearances. Moreover, eGFR, kidney-to-body weight ratio, GSH/GSSG ratio, KIM-1, NAG levels and mRNA expression of KIM-1 and osteopontin were also analyzed. Changes in histopathology of kidney and hematological parameters were also observed. Renogrit treatment led to an increase in cell viability, normalization of P-gp functionality, decrease in levels of NAG, KIM-1, and reduction in mRNA expression of NGAL and MMP-7. In Vancomycin-challenged SD rats, Renogrit treatment normalized altered kidney functions, histological, and hematological parameters. Our findings revealed that Renogrit holds a clinico-therapeutic potential for alleviating Vancomycin-associated nephrotoxicity.

Divya-WeightGo combined with moderate aerobic exercise remediates adiposopathy, insulin resistance, serum biomarkers, and hepatic lipid accumulation in high-fat diet-induced obese mice.

Obesity has become an unprecedented epidemic worldwide owing to a prolonged imbalance between energy intake and expenditure. Available therapies primarily suppress energy intake but often fail to produce sustained fat loss, necessitating a more efficacious strategy to combat obesity. In this study, a polyherbal formulation, Divya-WeightGo (DWG) has been investigated for its anti-obesity activity using in-vitro and in-vivo assays. Ultra-high performance liquid chromatography (UHPLC) analysis revealed the presence of phytocompounds including gallic acid, methyl gallate, corilagin, ellagic acid, pentagalloyl glucose, withaferin A and hydroxycitric acid, proven to aid in weight loss. The exposure of 3T3-L1 cells to DWG at cytosafe concentrations inhibited lipid and triglyceride accumulation and downregulated the expression of several adipogenic and lipogenic markers like PPARy, C/EBPα, C/EBPß, SREBP-1c, FASN and DGAT1. DWG reduced LPS-induced pro-inflammatory cytokine release and NF-κB activity in THP-1 cells. The in-vivo anti-obesity activity of DWG, both alone and in combination with moderate aerobic exercise, was assessed in a high fat diet-induced obese mouse model. DWG mitigated the obesity associated increased body weight gain, feed efficiency ratio, glucose intolerance, diminished insulin sensitivity, dyslipidemia, altered liver function profile, lipid accumulation and adiposopathy in obese mice, alone as well as in combination intervention, with better efficacy in the combination approach. Thus, the findings of this study suggest that DWG could be a promising therapeutic avenue to treat obesity through attenuation of lipid and fat accumulation in liver and adipose tissues and could be utilized as an adjunct with lifestyle interventions to combat obesity and associated complications.

2-{N-[(2,4,5-trichlorophenoxy) acetyl]-N-methylamino}-3-pyrrolidinepropanamide analogs as potential antagonists of Urotensin II receptor.

THE PURPOSE OF THE ARTICLE: To identify novel small molecule antagonists of Urotensin II receptor with acceptable pharmacological profile. MATERIALS AND METHODS: Structure-activity-relationship (SAR) studies on 2-{N-[(2,4,5-trichlorophenoxy) acetyl]-N-methylamino}-3-pyrrolidinepropanamide series were conducted and shortlisted compounds were synthesized and evaluated in in vitro cell-based assays. Human and mouse Urotensin II receptor overexpressing CHO cells were used for calcium release and radioligand binding assays. Initial molecules in this series had solubility and inter-species variability issue in the calcium release assay. We, therefore, conducted SAR to overcome these 2 issues and molecules with accepted in vitro profile were evaluated further in mouse pressor response model to generate the in vivo proof of concept for UII receptor antagonization. RESULTS AND CONCLUSIONS: We report herewith identification of 2-{N-[(2,4,5-trichlorophenoxy)acetyl]-N-methylamino}-3-pyrrolidinepropanamides series to obtain novel small molecule antagonists of Urotensin II receptor with acceptable pharmacological profile.

28-day repeated dose toxicological evaluation of Coronil in Sprague Dawley rats: Behavioral, hematological, biochemical and histopathological assessments under GLP compliance.

Ayurvedic medicines are widely employed globally for prophylaxis and treatment of a variety of diseases. Coronil is a tri-herbal medicine, constituted with the traditional herbs, Tinospora cordifolia, Withania somnifera and Ocimum sanctum, with known immunomodulatory activities. Based on its proven in-vitro activity and in-vivo efficacy, Coronil has been approved as a 'Supporting Measure for COVID-19' by the Ministry of AYUSH, Government of India. The current study was aimed to assess the non-clinical safety of Coronil in a 28-day repeated dose toxicity study along with a 14-day recovery period in Sprague Dawley rats. This toxicity study was conducted in accordance with OECD test guideline 407, under GLP-compliance. Specific-Pathogen-Free animals of either sex, housed in Individually-Ventilated-Cages were particularly used in the study. The tested Coronil dose levels were 0, 100, 300 and 1000 mg/kg/day, orally administered to 5 males and 5 female rats per test group. In the current study, no mortality was observed in any group and in addition, Coronil did not elicit any finding of toxicological relevance with respect to clinical signs, ocular effects, hematology, urinalysis and clinical chemistry parameters, as well as macro- or microscopical changes in any organs, when compared to the control group. Accordingly, the No-Observed-Adverse-Effect-Level (NOAEL) of Coronil was ascertained to be 1000 mg/kg/day, subsequent to its 28-day oral administration to male and female rats. The acceptable safety profile of Coronil paves the way further toxicity assessments in rodents for a longer duration as well as in higher animals, and towards its clinical investigation.

Withania somnifera (L.) Dunal whole-plant extract demonstrates acceptable non-clinical safety in rat 28-day subacute toxicity evaluation under GLP-compliance.

Withania somnifera (L.) Dunal (Ashwagandha) is widely used in Ayurveda, Unani and Siddha systems of medicines due to its therapeutic application in numerous ailments. Traditionally, the medications prepared from the plant employ only its roots and based on the currently available scientific literature, their efficacy and safety is well established. Apart from the roots, the aerial parts also contain bioactive components and correspondingly certain marketed preparations also employ the leaves of the plant. Accordingly, Ministry of Ayush, Government of India has lately issued an advisory emphasizing the need for extensive efficacy and safety profiling of leaf-based products. Consequently, we have conducted the present GLP-driven study, in which the non-clinical safety of a hydromethanolic extract of the whole plant of Withania somnifera (WSWPE) has been assessed according to OECD guideline 407. In this study Sprague Dawley rats of either sex were orally administered with WSWPE for 28-consecutive days at the doses of 100, 300 and 1000 mg/kg/day. The study also included a satellite group of animals that received WSWPE for 28-days followed by a 14-days recovery period. Withania somnifera Whole Plant Extract was found to be safe up to the dose level of 1000 mg/kg/day as no toxicologically relevant findings could be detected.

Peedanil Gold, Herbo-Mineral Formulation, Moderates Cytokine Levels and Attenuates Pathophysiology in Monosodium Iodoacetate Induced Osteoarthritis in SD Rat Model.

The inflammatory cartilaginous degeneration of the articular joints, mostly those of knee, hips and hands, is osteoarthritis (OA). The available treatment strategies for osteoarthritis are designed for pain relief, molecular targeting, cartilage regeneration and surgical intervention. However, meta-analysis of clinical trials has shown these strategies to be sub-optimal, thereby, eliciting a need for investigating alternative options. The herbo-mineral formulation, Peedanil Gold (PN-G) has been used against joint pains and inflammation. In the current study, anti-osteoarthritic effects of PN-G were investigated in rat model of OA, induced by intra-articular injection of monosodium-iodoacetate. PN-G treatment improved the clinical and Kellgren & Lawrence scores; and rescued the osteoarthritic rats from hyperalgesia and allodynia. Besides, PN-G treatment ameliorated joint inflammation and abrogated in vivo osteoarthritic pathology through effective cartilage regeneration, measured radiologically and histopathologically. PN-G also reduced the levels of interleukin-6 (IL-6) and interleukin-1 beta (IL-1ß), in a dose dependent manner, in inflamed human macrophagic THP-1 cells, thereby, reaffirming its anti-inflammatory property at cytosafe concentrations. Ultra High performance liquid chromatography (UHPLC) revealed the presence of several analgesic and anti-inflammatory phytocompounds, like ellagic acid, guggulsterone E, guggulsterone Z, 5-(hydroxymethyl) furfural, corilagin, cinnamic acid, ferulic acid, gallic acid and protocatechuic acid in PN-G. In conclusion, this study has succinctly demonstrated that PN-G is capable of relieving the clinical symptoms of osteoarthritis, which is measurable through the established osteoarthritic serum biomarker, Cartilage Oligomeric Matrix Protein (COMP).

Temporary mechanical circulatory support: insights and evolving strategies.

PURPOSE: The goal of this study is to evaluate the utilization and outcomes of temporary mechanical circulatory support (MCS) among patients listed for cardiac transplantation (CT). There is a constant threat of sudden clinical deterioration in these patients that could necessitate emergent MCS. All advanced heart failure and transplant centers in India are plagued by issues of late referrals, low organ donation rates, and financial constraints. Here, we share our experience and explain our evolving strategies tailored to improve outcomes. METHODS: Single-center retrospective analysis of temporary MCS implanted in patients listed for CT from January 1, 2015, to December 31, 2019. RESULTS: A total of 35 patients had 41 MCS implantations. Twenty-four cases were pre-transplant and 11 cases were post-transplant. Veno-arterial extracorporeal membrane oxygenator was the most commonly (20 cases, 44.4%) used MCS modality. Primary outcome of in-hospital mortality was noted in 17 patients (48.5%) in this high-risk profile. All but 2 of the 12 patients that underwent pre-transplant MCS, and were bridged to cardiac transplant, survived the index hospitalization accounting for 90% survival in this subset of patients. The secondary outcome of MCS-related vascular injury was observed in 9 patients (25.7%). CONCLUSION: This single-center observational study demonstrates that early planning and timely institution of MCS improves outcomes in high-risk MCS patients bridged to cardiac transplant. The incidence of MCS-related vascular complications can be improved with development of standard operating protocols.

Virtual crossmatch-prodigal saviour of cardiac transplants in India.

Positive anti-human leukocyte antigen (HLA) antibodies are considered a contraindication for cardiac transplantation in India, due to its negative impact on cardiac allograft survival and increased chances of rejection post-transplant. Single antigen bead (SAB) assay helps to further characterize these antibodies. Our case portrays India's first reported successful cardiac transplant utilizing a virtual crossmatch (VXM)-based approach in a patient with positive anti-HLA antibody screen and SAB assay. We propose that adopting such an approach, in select cases, in India is certainly feasible. This approach would lead to increasing the potential donor pool and mitigate the chances of post-transplant rejection. With increased demands, the SAB assay cost would reduce, further improving its cost-effectiveness.

Early experience with pediatric cardiac transplantation in a limited resource setting.

BACKGROUND: Pediatric heart transplantation is a now a well-established and standard treatment option for end stage heart failure for various conditions in children. Due to logistic issues, it is not an option for in most pediatric cardiac centres in the third world. AIM: We sought to describe our early experience in the current era in India. METHODS: This is a short term retrospective chart review of pediatric patients who underwent heart transplantation at our centre. Mean/Median with standard deviation /range was used to present data. RESULTS: Twenty patients underwent orthotopic heart transplant between January 2016 and June 2019. The median age at transplant was 12.4years (range 3.3 to 17.3 years). The median weight was 23.2kg (range 10-80kg). The mean donor/recipient weight ratio was 1.62± 0.84. The mean ICU stay was 12.1days. The mean follow up post transplant was 2.03± 0.97years (range 10 days-3.57years). The 1 month and the 1 year survival was 100%. Biopsies were positive for significant rejection in 7 patients (35%). At the time of last follow-up, 3 patients (15%) had expired. The major post transplant morbidities were mechanical circulatory support (n=3), hypertension with seizure complex (n=3), post transplant lympho-proliferative disorder (n=1), pseudocyst of pancreas (n=1), coronary allograft vasculopathy (n=3) and systemic hypertension (n=7). All surviving patients (n=17) were asymptomatic at last follow up. CONCLUSION: The results suggest acceptable short term outcomes in Indian pediatric patients can be achieved after heart transplantation in the current era. Significant rejection episodes and coronary allograft vasculopathy need careful follow up.

Identification of novel Urotensin-II receptor antagonists with potent inhibition of U-II induced pressor response in mice.

Urotensin II (U-II) has been found to be one of the most potent vasoconstrictor (Ames et al., 1999; Bohm et al., 2002) reported till date. U-II exerts its response via activation of a G-protein coupled receptor, Urotensin II receptor(UT). Binding of U-II to UT leads to an instant increase in the inositol phosphate turnover and intracellular Ca2+. Such an instant Ca2+ release and potent vasoconstriction exerted by U-II is expected to have an important role in the progression of cardiac diseases. We have previously shown that UT antagonist DS37001789 prevents U-II induced blood pressure elevation in mice (Nishi et al., 2019) in a dose dependent manner, with potent efficacy at 30 and 100 mg/kg. Further to this, we have also shown that DS37001789 ameliorates mortality in pressure-overload mice with heart failure (Nishi et al., 2020). We therefore conducted an extensive structure-activity relationship studies to identify molecules with superior efficacy. In the present manuscript, we report the identification of two potent, non-peptide small molecule antagonists of Urotensin II receptor (UT), RCI-0879 and RCI-0298 which blocked the action of U-II, both in vitro and in vivo. These molecules were found to be very potent in in vitro Ca2+ and radioligand binding assays using human and mouse UT over-expressing CHO cells. RCI-0879 and RCI-0298 also exhibited superior efficacy in in vivo mouse pressor response model using C57BL/6 mice, compared to our initial molecules (Nishi et al., 2019) and demonstrated ED50 values of 3.2 mg/kg and 6.8 mg/kg respectively. Our findings reported herewith, further strengthen our concept and belief in UT antagonization as a potential therapeutic approach for the management of chronic heart failure.

Proteomics analyses of subcutaneous adipocytes reveal novel abnormalities in human insulin resistance.

OBJECTIVE: To provide a more global view of adipocyte changes in human insulin resistance by proteomics analyses. METHODS: Baseline biopsies of abdominal subcutaneous adipose tissue were obtained from 23 subjects without diabetes. Euglycemic clamps were used to divide subjects into an insulin-resistant group (IR, N = 10) and an insulin-sensitive (IS, N = 13) group, which were of similar age and gender but unequal adiposity (greater in IR). Proteins of isolated adipocytes were quantified by mass spectrometry using normalized spectral abundance factors. RESULTS: Of 1,245 proteins assigned, 30 were detected in at least 12 of the 23 subjects that differed significantly in abundance ≥1.5-fold between IR and IS. IR displayed a pattern of increased cytoskeletal proteins and decreased mitochondrial proteins and FABP4 and FABP5. In subgroup analyses of adiposity-matched subjects, several of these changes were less pronounced in IR, but the abundance of proteins related to lipid metabolism and the unfolded/misfolded protein response were significantly and unfavorably altered. CONCLUSIONS: These results confirm lower abundance of mitochondrial proteins and suggest increased cytoskeletal proteins and decreased FABP4 and FABP5 in subcutaneous adipocytes of typical IR individuals. Changes in proteins related to lipid metabolism and the unfolded/misfolded protein may discriminate IR and IS individuals of equal adiposity.

NF-kappaB-inducing kinase (NIK) mediates skeletal muscle insulin resistance: blockade by adiponectin.

Enhanced levels of nuclear factor (NF)-κB-inducing kinase (NIK), an upstream kinase in the NF-κB pathway, have been implicated in the pathogenesis of chronic inflammation in diabetes. We investigated whether increased levels of NIK could induce skeletal muscle insulin resistance. Six obese subjects with metabolic syndrome underwent skeletal muscle biopsies before and six months after gastric bypass surgery to quantitate NIK protein levels. L6 skeletal myotubes, transfected with NIK wild-type or NIK kinase-dead dominant negative plasmids, were treated with insulin alone or with adiponectin and insulin. Effects of NIK overexpression on insulin-stimulated glucose uptake were estimated using tritiated 2-deoxyglucose uptake. NF-κB activation (EMSA), phosphatidylinositol 3 (PI3) kinase activity, and phosphorylation of inhibitor κB kinase ß and serine-threonine kinase (Akt) were measured. After weight loss, skeletal muscle NIK protein was significantly reduced in association with increased plasma adiponectin and enhanced AMP kinase phosphorylation and insulin sensitivity in obese subjects. Enhanced NIK expression in cultured L6 myotubes induced a dose-dependent decrease in insulin-stimulated glucose uptake. The decrease in insulin-stimulated glucose uptake was associated with a significant decrease in PI3 kinase activity and protein kinase B/Akt phosphorylation. Overexpression of NIK kinase-dead dominant negative did not affect insulin-stimulated glucose uptake. Adiponectin treatment inhibited NIK-induced NF-κB activation and restored insulin sensitivity by restoring PI3 kinase activation and subsequent Akt phosphorylation. These results indicate that NIK induces insulin resistance and further indicate that adiponectin exerts its insulin-sensitizing effect by suppressing NIK-induced skeletal muscle inflammation. These observations suggest that NIK could be an important therapeutic target for the treatment of insulin resistance associated with inflammation in obesity and type 2 diabetes.

Pharmacodynamic and pharmacokinetic profile of RBx 343E48F0: a novel, long acting muscarinic receptor antagonist.

RBx 343E48F0 is a novel, potent, selective and long acting muscarinic receptor antagonist with a potential for use in the treatment of Chronic Obstructive Pulmonary Disease (COPD). The aim of the present study was to describe the in vitro and in vivo profile of RBx 343E48F0 and to compare the results with the present day benchmark therapy, tiotropium. Radioligand binding and isolated tissue based functional assays were used to evaluate the affinity, potency and receptor subtype selectivity of RBx 343E48F0. Inhibition of carbachol-induced bronchoconstriction in the anaesthetized rat and acetylcholine-induced bronchoconstriction in the conscious rat were used to assess the extent and duration of the bronchospasmolytic activity of RBx 343E48F0. In vitro and in vivo pharmacokinetic studies were conducted to evaluate the pharmacokinetic and lung retention properties of the compound. In vitro radioligand binding studies using human recombinant muscarinic receptors showed that RBx 343E48F0 had a pKi of 9.6 at the M(3) receptor and a 60-fold selectivity for the M(3) receptor over the M(2) receptor. In isolated tissue bioassays, it exhibited surmountable antagonism at the guinea pig trachea with a pK(B) of 9.5. Intratracheal administration to anaesthetized rats demonstrated a dose-dependent inhibition of carbachol-induced bronchoconstriction with an ED(50) value of 110 ng/kg. RBx 343E48F0 also exhibited a fast onset of action and long duration of action of greater 24h.

Characterization of the Human Adipocyte Proteome and Reproducibility of Protein Abundance by One-Dimensional Gel Electrophoresis and HPLC-ESI-MS/MS.

Abnormalities in adipocytes play an important role in various conditions, including the metabolic syndrome, type 2 diabetes mellitus and cardiovascular disease, but little is known about alterations at the protein level. We therefore sought to (1) comprehensively characterize the human adipocyte proteome for the first time and (2) demonstrate feasibility of measuring adipocyte protein abundances by one-dimensional SDS-PAGE and high performance liquid chromatography-electron spray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). In adipocytes isolated from approximately 0.5 g of subcutaneous abdominal adipose tissue of three healthy, lean subjects, we identified a total of 1493 proteins. Triplicate analysis indicated a 22.5% coefficient of variation of protein abundances. Proteins ranged from 5.8 to 629 kDa and included a large number of proteins involved in lipid metabolism, such as fatty acid transport, fatty acid oxidation, lipid storage, lipolysis, and lipid droplet maintenance. Furthermore, we found most glycolysis enzymes and numerous proteins associated with oxidative stress, protein synthesis and degradation as well as some adipokines. 22% of all proteins were of mitochondrial origin. These results provide the first detailed characterization of the human adipocyte proteome, suggest an important role of adipocyte mitochondria, and demonstrate feasibility of this approach to examine alterations of adipocyte protein abundances in human diseases.

Amino acid metabolism and inflammatory burden in ovarian cancer patients undergoing intense oncological therapy.

BACKGROUND & AIMS: Cancer and oncological therapy are associated with a progressive physical deterioration, malnutrition, and enhanced inflammatory burden. Our considerable data showing the strong anabolic potential of amino acids (AA) led us to test whether AA can acutely stimulate muscle protein synthesis in cancer patients (CA) undergoing intense chemotherapy. METHODS: Mixed muscle fractional synthesis rate (FSR), rates of phenylalanine appearance and disappearance (Ra and Rd), and net phenylalanine balance (NB) were measured during a primed constant infusion of L-[ring-(2)H(5)]phenylalanine. Blood and muscle tissue samples were collected in the basal state and following ingestion of 40 g of AA given in 30 mL boluses every 10 min for 3h. Serum and tissue cytokines and NF-kappaB expression in skeletal muscle were measured and compared to normative, healthy older controls (OC). RESULTS: Skeletal muscle TNF-alpha, IL-6, and NF-kappaB were elevated in CA. FSR and model-derived protein synthesis (Rd) increased significantly from basal to AA (FSR: 0.052+/-0.009 vs. 0.120+/-0.008%h(-1), P<0.001; Rd: 23.1+/-4.1 vs. 36.4+/-5.0 nmol min(-1) 100 mL leg(-1), P0.05). Model-derived protein breakdown (Ra) remained unchanged from basal to AA. Phenylalanine NB improved from a negative basal value (-16+/-2) to zero (0.8+/-6 nmol min(-1) 100 ml leg(-1), P0.05) following AA. CONCLUSION: Despite advanced cancer, ongoing therapy, and an enhanced inflammatory burden, AA were capable of acutely stimulating muscle protein synthesis in these patients.

Comparative in vivo uroselectivity profiles of anticholinergics, tested in a novel anesthetized rabbit model.

The aim of this study was to describe a new experimental animal model for simultaneous measurement of carbachol-induced increase in intravesical pressure and salivary secretion in rabbits. Further, we also compared the in vivo potency and urinary bladder versus salivary gland selectivity profiles of Oxybutynin, Tolterodine, Solifenacin and Darifenacin. The intravesical pressure and salivary secretion were evoked by intra-arterial injection of carbachol (1.5 microg/kg). The carbachol-induced increase in intravesical pressure and salivation was simultaneously recorded before and after increasing doses of test drugs administered intravenously. The basal mean changes in intravesical pressure and salivation subsequent to carbachol administration were in the range of 6.7-7.5 mm Hg and 0.5-0.7 g respectively. Repeated administration of vehicle did not elicit any appreciable changes in intravesical pressure and salivary secretion to carbachol administration from the basal values till 3 h. All the test drugs exhibited a dose-dependent inhibition of carbachol-induced increase in intravesical pressure and salivary secretion. Darifenacin demonstrated a greater potency compared to other muscarinic receptor antagonists for inhibiting carbachol-induced increase in intravesical pressure. It also exhibited functional selectivity for the urinary bladder versus salivary gland. In contrast, Oxybutynin was functionally more selective in inhibiting carbachol-induced increase in salivary secretion. The observed urinary bladder versus salivary selectivity values were 0.6+/-0.2, 1.1+/-0.2, 1.7+/-0.5, and 2.3+/-0.5 for Oxybutynin, Tolterodine, Solifenacin and Darifenacin respectively. These results suggest that the functional selectivity of muscarinic receptor antagonists between urinary bladder and salivary glands can be readily detected in this model. Thus rabbits may represent a useful animal model for evaluating putative bladder selective muscarinic receptor antagonists for the treatment of overactive bladder.

Fatty acid-induced insulin resistance in L6 myotubes is prevented by inhibition of activation and nuclear localization of nuclear factor kappa B.

Recent studies have implicated inhibitor of kappaB kinase (IKK) in mediating fatty acid (FA)-induced insulin resistance. How IKK causes these effects is unknown. The present study addressed the role of nuclear factor kappaB (NFkappaB), the distal target of IKK activity, in FA-induced insulin resistance in L6 myotubes, an in vitro skeletal muscle model. A 6-h exposure of myotubes to the saturated FA palmitate reduced insulin-stimulated glucose uptake by approximately 30%, phosphatidylinositol-3 kinase and protein kinase B phosphorylation by approximately 40%, and stimulated inhibitor of kappaBalpha degradation and the nuclear translocation of NFkappaB. On the other hand, the Omega-3 polyunsaturated FA linolenate neither induced insulin resistance nor promoted nuclear localization of NFkappaB. Supporting the hypothesis that IKK acts through NFkappaB to cause insulin resistance, the IKK inhibitors acetylsalicylate and parthenolide prevented FA-induced reductions in insulin-stimulated glucose uptake and NFkappaB nuclear translocation. Most importantly, NFkappaB SN50, a cell-permeable peptide that inhibits NFkappaB nuclear translocation downstream of IKK, was sufficient to prevent palmitate-induced reductions in insulin-stimulated glucose uptake. Acetylsalicylate, but not NFkappaB SN50, prevented FA effects on phosphatidylinositol-3 kinase activity and protein kinase B phosphorylation. We conclude that FAs induce insulin resistance and activates NFkappaB in L6 cells. Furthermore, inhibition of NFkappaB activation, indirectly by preventing IKK activation or directly by inhibiting NFkappaB nuclear translocation, prevents the detrimental effects of palmitate on the metabolic actions of insulin in L6 myotubes.