title: Effect of fasting and thyroidectomy on cysteine proteinase activities in liver and muscle.
abstract: Prolonged starvation mimics chronic negative nitrogen balance observed in many physiopathological situations. During starvation, an initial decrease in protein utilization (phase I) is followed by a long period of protein sparing (phase II) that ends with a marked rise in nitrogen excretion (phase III). Variations in protein metabolism during starvation are determined by changes in protein synthesis and degradation rates (Cherel, Y., Attaix, D. Rosolowska-Huszcz, D., Belkhou, R., Robin, J.P., Arnal, M. and Le Maho, Y. (1991) Clin. Sci. 81, 611-619), but little information is available on expression of proteolytic systems. In this study, cathepsin B, H and L activities were compared in hindlimb muscles and liver at various phases of starvation in thyroidectomized and sham-operated rats. In muscle, cathepsin activities fell from the fed state to phase II, which suggests that cathepsins may play a role in the curtailment of muscle proteolysis during protein sparing phase. This decrease of muscle cathepsin activities was reproduced by thyroidectomy alone. In contrast, liver cathepsin B and H activities fell during starvation, but were not affected by thyroidectomy alone. Liver cathepsin L decreased only during starvation in thyroidectomized animals. These observations emphasize that different mechanisms modulate cathepsin expression in skeletal muscle and liver.
authors.affiliation: Centre d'Ecologie et de Physiologie Energétiques, Centre National de la Recherche Scientifique, Strasbourg, France.
authors.forename: R
authors.initials: R
authors.lastname: Belkhou
authors.forename: D
authors.initials: D
authors.lastname: Béchet
authors.forename: Y
authors.initials: Y
authors.lastname: Cherel
authors.forename: M
authors.initials: M
authors.lastname: Galluser
authors.forename: M
authors.initials: M
authors.lastname: Ferrara
authors.forename: Y
authors.initials: Y
authors.lastname: le Maho
mesh_terms: D000818:Animals; D002401:Cathepsin B / Q000378:metabolism; D056655:Cathepsin H; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D010450:Endopeptidases; D005215:Fasting / Q000502:physiology*; D008099:Liver / Q000201:enzymology*; D008297:Male; D009132:Muscles / Q000201:enzymology*; D009584:Nitrogen / Q000652:urine; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D012044:Regression Analysis; D013963:Thyroid Hormones / Q000502:physiology*; D013965:Thyroidectomy; D013974:Thyroxine / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L; C534280:Ctsl protein, rat; D056655:Cathepsin H; C534128:Ctsh protein, rat; D009584:Nitrogen; D013974:Thyroxine; D003345:Corticosterone