title: The sympathetic nervous system regulates the three glycerol-3P generation pathways in white adipose tissue of fasted, diabetic and high-protein diet-fed rats.
abstract: The aim of the present study was to investigate the participation of the sympathetic nervous system (SNS) in the control of glycerol-3-P (G3P) generating pathways in white adipose tissue (WAT) of rats in three situations in which the plasma insulin levels are low. WAT from 48 h fasted animals, 3 day-streptozotocin diabetic animals and high-protein, carbohydrate-free (HP) diet-fed rats was surgical denervated and the G3P generation pathways were evaluated. Food deprivation, diabetes and the HP diet provoke a marked decrease in the rate of glucose uptake and glycerokinase (GyK) activity, but a significant increase in the glyceroneogenesis, estimated by the phosphoenolpyruvate carboxykinase (PEPCK) activity and the incorporation of 1-[(14)C]-pyruvate into glycerol-TAG. The denervation provokes a reduction (~70%) in the NE content of WAT in fasted, diabetic and HP diet-fed rats. The denervation induced an increase in WAT glucose uptake of fed, fasted, diabetic and HP diet-fed rats (40%, 60%, 3.2 fold and 35%, respectively). TAG-glycerol synthesis from pyruvate was reduced by denervation in adipocytes of fed (58%) and fasted (36%), saline-treated (58%) and diabetic (23%), and HP diet-fed rats (11%). In these same groups the denervation reduced the PEPCK mRNA expression (75%-95%) and the PEPCK activity (35%-60%). The denervation caused a ~35% decrease in GyK activity of control rats and a further ~35% reduction in the already low enzyme activity of fasted, diabetic and HP diet-fed rats. These data suggest that the SNS plays an important role in modulating G3P generating pathways in WAT, in situations where insulin levels are low.
authors.affiliation: Department of Biochemistry-Immunology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Danúbia
authors.initials: D
authors.lastname: Frasson
authors.forename: Renata Polessi
authors.initials: RP
authors.lastname: Boschini
authors.forename: Valéria Ernestânia
authors.initials: VE
authors.lastname: Chaves
authors.forename: Maria Emília Soares Martins
authors.initials: ME
authors.lastname: dos Santos
authors.forename: Sílvia de
authors.initials: S
authors.lastname: Paula Gomes
authors.forename: Rafael Rossi
authors.initials: RR
authors.lastname: Valentim
authors.forename: Maria Antonieta Rissato
authors.initials: MA
authors.lastname: Garófalo
authors.forename: Luiz Carlos Carvalho
authors.initials: LC
authors.lastname: Navegantes
authors.forename: Renato Hélios
authors.initials: RH
authors.lastname: Migliorini
authors.forename: Isis do Carmo
authors.initials: Ido C
authors.lastname: Kettelhut
mesh_terms: D052436:Adipose Tissue, White / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage*; D005215:Fasting / Q000378:metabolism*; D005943:Gluconeogenesis; D005947:Glucose / Q000378:metabolism; D005991:Glycerol Kinase / Q000378:metabolism; D005994:Glycerophosphates / Q000096:biosynthesis*; D007328:Insulin / Q000097:blood; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D004044:Dietary Proteins; D005994:Glycerophosphates; D007328:Insulin; D013311:Streptozocin; D005991:Glycerol Kinase; D005947:Glucose; D009638:Norepinephrine