title: Anabolic effect of plant brassinosteroid.
abstract: Brassinosteroids are plant-derived polyhydroxylated derivatives of 5a-cholestane, structurally similar to cholesterol-derived animal steroid hormones and insect ecdysteroids, with no known function in mammals. 28-Homobrassinolide (HB), a steroidal lactone with potent plant growth-promoting property, stimulated protein synthesis and inhibited protein degradation in L6 rat skeletal muscle cells (EC(50) 4 μM) mediated in part by PI3K/Akt signaling pathway. Oral administration of HB (20 or 60 mg/kg/d for 24 d) to healthy rats fed normal diet (protein content 23.9%) increased food intake, body weight gain, lean body mass, and gastrocnemius muscle mass as compared with vehicle-treated controls. The effect of HB administration increased slightly in animals fed a high-protein diet (protein content 39.4%). Both oral (up to 60 mg/kg) and subcutaneous (up to 4 mg/kg) administration of HB showed low androgenic activity when tested in the Hershberger assay. Moreover, HB showed no direct binding to the androgen receptor in vitro. HB treatment was also associated with an improved physical fitness of untrained healthy rats, as evident from a 6.7% increase in lower extremity strength, measured by grip test. In the gastrocnemius muscle of castrated animals, HB treatment significantly increased the number of type IIa and IIb fibers and the cross-sectional area of type I and type IIa fibers. These findings suggest that oral application of HB triggers selective anabolic response with minimal or no androgenic side-effects and begin to elucidate the putative cellular targets for plant brassinosteroids in mammals.
authors: Biotech Center, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey, USA.
authors: Debora
authors: D
authors: Esposito
authors: Slavko
authors: S
authors: Komarnytsky
authors: Sue
authors: S
authors: Shapses
authors: Ilya
authors: I
authors: Raskin
mesh_terms: D045930:Anabolic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001823:Body Composition / Q000187:drug effects; D002477:Cells; D002778:Cholestanones / Q000008:administration & dosage / Q000494:pharmacology*; D004044:Dietary Proteins; D007928:Lethal Dose 50; D008297:Male; D015394:Molecular Structure; D018485:Muscle Fibers, Skeletal / Q000187:drug effects; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects*; D009919:Orchiectomy; D051381:Rats; D017208:Rats, Wistar
chemical_list: D045930:Anabolic Agents; D002778:Cholestanones; D004044:Dietary Proteins; C070163:homobrassinolide