Gender Dimorphism in Skeletal Muscle Leptin Receptors, Serum Leptin and Insulin Sensitivity

Abstract

Todetermineifthereisagenderdimorphismintheexpressionof leptinreceptors(OB-R170,OB-R128andOB-R98)andthe proteinsuppressorofcytokinesignaling3(SOCS3) inhumanskeletalmuscle, theproteinexpressionofOB-R,perilipinA, SOCS3andalpha-tubulinwasassessedbyWesternblot inmusclebiopsiesobtainedfromthem.vastus lateralis inthirty fourmen(age=27.166.8yr) andthirty-threewomen(age=26.766.7yr). Basal seruminsulinconcentrationandHOMA weresimilar inbothgenders.Serumleptinconcentrationwas3.4timeshigher inwomencomparedtomen(P,0.05)and thisdifferenceremainedsignificantafteraccountingforthedifferencesinpercentageofbodyfatorsolubleleptinreceptor. OB-Rproteinwas 41%(OB-R170, P,0.05) and163%(OB-R128, P,0.05) greater inwomen thanmen. Therewas no relationshipbetweenOB-Rexpressionandtheserumconcentrationsof leptinor17b-estradiol. Inmen,muscleOB-R128 proteinwas inverselyrelatedtoserumfreetestosterone. Inwomen,OB-R98andOB-R128wereinverselyrelatedtototal serumtestosteroneconcentration,andOB-R128toserumfreetestosteroneconcentration.SOCS3proteinexpressionwas similarinmenandwomenandwasnotrelatedtoOB-R. Inwomen,therewasaninverserelationshipbetweenthelogarithm of free testosteroneandSCOS3proteincontent inskeletalmuscle (r=20.46, P,0.05). Insummary, there is agender dimorphisminskeletalmuscleleptinreceptorsexpression,whichcanbepartlyexplainedbytheinfluenceoftestosterone. SOCS3 expression in skeletal muscle is not up-regulated inwomen, despite very high serum leptin concentrations comparedtomen.Thecirculatingformof theleptinreceptorcannotbeusedasasurrogatemeasureof theamountof leptinreceptorsexpressedinskeletalmuscles.