title: Gestational protein restriction impairs insulin-regulated glucose transport mechanisms in gastrocnemius muscles of adult male offspring.
abstract: Type II diabetes originates from various genetic and environmental factors. Recent studies showed that an adverse uterine environment such as that caused by a gestational low-protein (LP) diet can cause insulin resistance in adult offspring. The mechanism of insulin resistance induced by gestational protein restriction is not clearly understood. Our aim was to investigate the role of insulin signaling molecules in gastrocnemius muscles of gestational LP diet-exposed male offspring to understand their role in LP-induced insulin resistance. Pregnant Wistar rats were fed a control (20% protein) or isocaloric LP (6%) diet from gestational day 4 until delivery and a normal diet after weaning. Only male offspring were used in this study. Glucose and insulin responses were assessed after a glucose tolerance test. mRNA and protein levels of molecules involved in insulin signaling were assessed at 4 months in gastrocnemius muscles. Muscles were incubated ex vivo with insulin to evaluate insulin-induced phosphorylation of insulin receptor (IR), Insulin receptor substrate-1, Akt, and AS160. LP diet-fed rats gained less weight than controls during pregnancy. Male pups from LP diet-fed mothers were smaller but exhibited catch-up growth. Plasma glucose and insulin levels were elevated in LP offspring when subjected to a glucose tolerance test; however, fasting levels were comparable. LP offspring showed increased expression of IR and AS160 in gastrocnemius muscles. Ex vivo treatment of muscles with insulin showed increased phosphorylation of IR (Tyr972) in controls, but LP rats showed higher basal phosphorylation. Phosphorylation of Insulin receptor substrate-1 (Tyr608, Tyr895, Ser307, and Ser318) and AS160 (Thr642) were defective in LP offspring. Further, glucose transporter type 4 translocation in LP offspring was also impaired. A gestational LP diet leads to insulin resistance in adult offspring by a mechanism involving inefficient insulin-induced IR, Insulin receptor substrate-1, and AS160 phosphorylation and impaired glucose transporter type 4 translocation.
authors.affiliation: Department of Obstetrics and Gynecology (C.S.B., C.Y.), Baylor College of Medicine, Houston, Texas 77030; and Division of Reproductive Endocrinology (K.S., V.C.), Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas 77555.
authors.forename: Chellakkan S
authors.initials: CS
authors.lastname: Blesson
authors.forename: Kunju
authors.initials: K
authors.lastname: Sathishkumar
authors.forename: Vijayakumar
authors.initials: V
authors.lastname: Chinnathambi
authors.forename: Chandrasekhar
authors.initials: C
authors.lastname: Yallampalli
mesh_terms: D000818:Animals; D018753:Diet, Protein-Restricted / Q000009:adverse effects*; D005260:Female; D020690:GTPase-Activating Proteins / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D007328:Insulin / Q000097:blood; D055504:Insulin Receptor Substrate Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007333:Insulin Resistance; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011972:Receptor, Insulin / Q000378:metabolism; D015430:Weight Gain
chemical_list: D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; C495694:Slc2a4 protein, rat; C533101:TBC1D4 protein, rat; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt; D005947:Glucose