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Increased protein turnover and proteolysis is an early and primary feature of short-term experimental hyperthyroidism in healthy women.
J Clin Endocrinol Metab. 2008 Oct; 93(10):3999-4005.JC

Abstract

CONTEXT

Hyperthyroidism increases energy expenditure, glucose turnover, lipolysis, and protein breakdown.

OBJECTIVE

Our objective was to test whether increased protein breakdown occurs independently of other catabolic effects in mild experimental hyperthyroidism.

DESIGN

We conducted a single-blind, randomized, placebo-controlled, crossover study. Protein dynamics of the whole body and of the forearm muscles were measured by amino acid tracer dilution technique ([(15)N]phenylalanine and [(2)H(4)]tyrosine). All subjects underwent a 3-h study in the basal state followed by a 3-h euglycemic clamp study.

SETTING

The study took place at a university clinical research unit.

PARTICIPANTS

Eight healthy women (24-46 yr old) participated.

INTERVENTION

Intervention included 6 d thyroid hormone (T(4) 50 microg and T(3) 0.67 microg/kg.d) or placebo administration.

RESULTS

Thyroid hormone administration led to mild T(3) hyperthyroidism with more than a doubling of T(3) levels and suppression of TSH. Energy expenditure and body composition was unchanged. Glucose infusion rates, forearm glucose uptake, and levels of lipid intermediates were also alike. Basal whole-body phenylalanine flux and tyrosine flux (reflecting whole-body protein breakdown) were increased (P < 0.05) as were whole-body protein synthesis rate (P = 0.05). Basal forearm rate of appearance and disappearance for phenylalanine (reflecting muscle protein breakdown and synthesis) were similar.

CONCLUSIONS

Mild short-term experimental hyperthyroidism increases whole-body protein turnover and breakdown before any measurable changes in energy expenditure or glucose and fat metabolism, suggesting that amino acid and protein metabolism is an early and primary target for thyroid hormone action in humans.

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Authors+Show Affiliations

Riis AL
Medical Department M, Aarhus University Hospital, 8000 Aarhus C, Denmark. anne.lene.riis@ki.au.dk
Jørgensen JO
No affiliation info available
Ivarsen P
No affiliation info available
Frystyk J
No affiliation info available
Weeke J
No affiliation info available
Møller N
No affiliation info available

MeSH

AdultAmino AcidsBody CompositionCross-Over StudiesEnergy MetabolismFemaleHealthHumansHyperthyroidismInsulin ResistanceMiddle AgedMusclesPlacebosProtein Processing, Post-TranslationalProteinsSingle-Blind MethodThyroid HormonesTime FactorsUp-Regulation

Pub Type(s)

Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

18628521

Citation

Riis, Anne Lene Dalkjaer, et al. "Increased Protein Turnover and Proteolysis Is an Early and Primary Feature of Short-term Experimental Hyperthyroidism in Healthy Women." The Journal of Clinical Endocrinology and Metabolism, vol. 93, no. 10, 2008, pp. 3999-4005.
Riis AL, Jørgensen JO, Ivarsen P, et al. Increased protein turnover and proteolysis is an early and primary feature of short-term experimental hyperthyroidism in healthy women. J Clin Endocrinol Metab. 2008;93(10):3999-4005.
Riis, A. L., Jørgensen, J. O., Ivarsen, P., Frystyk, J., Weeke, J., & Møller, N. (2008). Increased protein turnover and proteolysis is an early and primary feature of short-term experimental hyperthyroidism in healthy women. The Journal of Clinical Endocrinology and Metabolism, 93(10), 3999-4005. https://doi.org/10.1210/jc.2008-0550
Riis AL, et al. Increased Protein Turnover and Proteolysis Is an Early and Primary Feature of Short-term Experimental Hyperthyroidism in Healthy Women. J Clin Endocrinol Metab. 2008;93(10):3999-4005. PubMed PMID: 18628521.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Increased protein turnover and proteolysis is an early and primary feature of short-term experimental hyperthyroidism in healthy women. AU - Riis,Anne Lene Dalkjaer, AU - Jørgensen,Jens Otto Lunde, AU - Ivarsen,Per, AU - Frystyk,Jan, AU - Weeke,Jørgen, AU - Møller,Niels, Y1 - 2008/07/15/ PY - 2008/7/17/pubmed PY - 2008/12/17/medline PY - 2008/7/17/entrez SP - 3999 EP - 4005 JF - The Journal of clinical endocrinology and metabolism JO - J Clin Endocrinol Metab VL - 93 IS - 10 N2 - CONTEXT: Hyperthyroidism increases energy expenditure, glucose turnover, lipolysis, and protein breakdown. OBJECTIVE: Our objective was to test whether increased protein breakdown occurs independently of other catabolic effects in mild experimental hyperthyroidism. DESIGN: We conducted a single-blind, randomized, placebo-controlled, crossover study. Protein dynamics of the whole body and of the forearm muscles were measured by amino acid tracer dilution technique ([(15)N]phenylalanine and [(2)H(4)]tyrosine). All subjects underwent a 3-h study in the basal state followed by a 3-h euglycemic clamp study. SETTING: The study took place at a university clinical research unit. PARTICIPANTS: Eight healthy women (24-46 yr old) participated. INTERVENTION: Intervention included 6 d thyroid hormone (T(4) 50 microg and T(3) 0.67 microg/kg.d) or placebo administration. RESULTS: Thyroid hormone administration led to mild T(3) hyperthyroidism with more than a doubling of T(3) levels and suppression of TSH. Energy expenditure and body composition was unchanged. Glucose infusion rates, forearm glucose uptake, and levels of lipid intermediates were also alike. Basal whole-body phenylalanine flux and tyrosine flux (reflecting whole-body protein breakdown) were increased (P < 0.05) as were whole-body protein synthesis rate (P = 0.05). Basal forearm rate of appearance and disappearance for phenylalanine (reflecting muscle protein breakdown and synthesis) were similar. CONCLUSIONS: Mild short-term experimental hyperthyroidism increases whole-body protein turnover and breakdown before any measurable changes in energy expenditure or glucose and fat metabolism, suggesting that amino acid and protein metabolism is an early and primary target for thyroid hormone action in humans. SN - 0021-972X UR - https://www.unboundmedicine.com/medline/citation/18628521/Increased_protein_turnover_and_proteolysis_is_an_early_and_primary_feature_of_short_term_experimental_hyperthyroidism_in_healthy_women_ L2 - https://academic.oup.com/jcem/article-lookup/doi/10.1210/jc.2008-0550 DB - PRIME DP - Unbound Medicine ER -