title: An extract of Urtica dioica L. mitigates obesity induced insulin resistance in mice skeletal muscle via protein phosphatase 2A (PP2A).
abstract: The leaf extract of Urtica dioica L. (UT) has been reported to improve glucose homeostasis in vivo, but definitive studies on efficacy and mechanism of action are lacking. We investigated the effects of UT on obesity- induced insulin resistance in skeletal muscle. Male C57BL/6J mice were divided into three groups: low-fat diet (LFD), high-fat diet (HFD) and HFD supplemented with UT. Body weight, body composition, plasma glucose and plasma insulin were monitored. Skeletal muscle (gastrocnemius) was analyzed for insulin sensitivity, ceramide accumulation and the post translational modification and activity of protein phosphatase 2A (PP2A). PP2A is activated by ceramides and dephosphorylates Akt. C2C12 myotubes exposed to excess free fatty acids with or without UT were also evaluated for insulin signaling and modulation of PP2A. The HFD induced insulin resistance, increased fasting plasma glucose, enhanced ceramide accumulation and PP2A activity in skeletal muscle. Supplementation with UT improved plasma glucose homeostasis and enhanced skeletal muscle insulin sensitivity without affecting body weight and body composition. In myotubes, UT attenuated the ability of FFAs to induce insulin resistance and PP2A hyperactivity without affecting ceramide accumulation and PP2A expression. UT decreased PP2A activity through posttranslational modification that was accompanied by a reduction in Akt dephosphorylation.
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA.
authors.forename: Diana N
authors.initials: DN
authors.lastname: Obanda
authors.affiliation: Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, USA.
authors.forename: David
authors.initials: D
authors.lastname: Ribnicky
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Stephens
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA.
authors.forename: William T
authors.initials: WT
authors.lastname: Cefalu
mesh_terms: D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002460:Cell Line; D059305:Diet, High-Fat; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism*; D009765:Obesity / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D015398:Signal Transduction; D026982:Urtica dioica / Q000737:chemistry*
chemical_list: D007328:Insulin; D010936:Plant Extracts; D006003:Glycogen; D054648:Protein Phosphatase 2; D005947:Glucose