Psychoneuroendocrine effects of combined thyroxine and triiodothyronine versus tyrosine during prolonged Antarctic residence

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Palinkas, Lawrence A. ; Reedy, Kathleen R. ; Smith, Mark ; Anghel, Mihai ; Steel, Gary D. ; Reeves, Dennis ; Shurtleff, David ; Case, H. Samuel ; Do, Nhan Van ; Reed, H. Lester (2007)
  • Publisher: Co-Action Publishing
  • Journal: International Journal of Circumpolar Health (issn: 1797-237X, eissn: 1239-9736)
  • Related identifiers: doi: 10.3402/ijch.v66i5.18312
  • Subject: clinical trial; cognition; cold; mood; thyroid hormones; tyrosine

OBJECTIVES: We previously reported that cognitive function improves with thyroxine and that there is a circannual pattern to mood and human TSH during Antarctic residence. To extend these findings, we examined the effects of tyrosine and a combined levothyroxine/liothyronine supplement in euthyroid men and women who spent the austral summer (n = 43) and/or winter (n = 42) in Antarctica. STUDY DESIGN: Randomized, placebo-controlled, clinical trial. METHODS: Subjects were randomized to receive the following each day for 91.6 +/- 3.2 days in summer and/or 138.0 +/- 3.2 days in winter: (1) 12g tyrosine mixed in 113g applesauce; (2) 50 microg of levothyroxine and 12.5 microg of liothyronine (T4-T3 Supplement); or (3) placebo. Cognitive performance and mood were assessed using the Automatic Neuropsychological Assessment Metric - Isolated and Confined Environments. RESULTS: With placebo in summer, mood did not change while TSH decreased by 28%; in winter, there was a 136% degradation in mood (p < 0.01) and TSH increased by 18%. With combined T4-T3 supplement, there was a 51% degradation in mood in summer compared with placebo (p < 0.05) and TSH decreased by 57%; in winter there was a 135% degradation in mood while TSH was reduced by 26% (p < 0.05). Tyrosine use in summer was associated with no change in mood and a 30% decline in TSH, while in winter there was a 47% improvement in mood and TSH decreased by 28% along with a 6% increase in fT3 (p < 0.05). CONCLUSIONS: Administration of tyrosine leads to a significant reduction in serum TSH and improvement in mood in winter compared with placebo, while the combined T4-T3 supplement leads to a worsening of mood in summer and no improvement in winter. There appears to be a seasonal influence on the psychological response to interventions and the relationship to changes in TSH reductions.Keywords: clinical trial; cognition; cold; mood; thyroid hormones; tyrosine(Int J Circumpolar Health 2007; 66(5):401-417)
  • References (52)
    52 references, page 1 of 6

    1. Do NV, LeMar H, Reed HL. Thyroid hormone responses to environmental cold exposure and seasonal change: a proposed model. Endocrinol Metab 1996;3:7-16.

    2. Harford RR, Reed HL, Morris MT, Sapien IE, Warden R, D'Alesandro MM. Relationship between changes in serum thyrotropin and total and lipoprotein cholesterol with prolonged Antarctic residence. Metabolism 1993;42:1159-1163.

    3. Reed HL, Ferreiro JA, Shakir KM, Burman KD, O'Brian JT. Pituitary and peripheral hormone responses to T3 administration during Antarctic residence. Am J Physiol 1988;254:E733-E739.

    4. Reed HL. Environmental influences upon thyroid hormone regulation. In: Braverman LE, Utiger RD, editors. Werner and Ingbar's The Thyroid: A Fundamental and Clinical Text. 8th ed. Philadelphia: Lippincott-Raven; 2000. p. 257-265.

    5. Savourey G, Barnavol B, Caravel JP, Feuerstein C, Bittel JH. Hypothermic general cold adaptation induced by local cold acclimation. Eur J Appl Physiol Occup Physiol 1996;73:237-244.

    6. Reed HL, Reedy KR, Palinkas LA, Do NV, Finney NS, Case HS, et al. Impairment in cognitive and exercise performance during prolonged Antarctic residence: effect of thyroxine supplementation in the Polar T3 syndrome. J Clin Endocrinol Metab 2001;86:110- 116.

    7. Reed HL, Silverman ED, Shakir KM, Dons R, Burman KD, O'Brian JT. Changes in serum triiodothyronine (t3) kinetics after prolonged Antarctic residence: the polar T3 syndrome. J Clin Endocrinol Metab 1990; 70:965-974.

    8. Reed HL, Brice D, Shakir KM, Burman KD, D'Alesandro MM, O'Brian JT. Decreased free fraction of thyroid hormones after prolonged Antarctic residence. J Appl Physiol 1990;69:1467-1472.

    9. Case HS, Reed HL, Palinkas LA, Reedy KR, Do NV, Finney NS, et al. Resting and exercise energy use in Antarctica: effect of 50% dietary restriction on the Polar T3 syndrome. Clin Endocrinol 2006;65:257-265.

    10. Hassi J, Sikkilä K, Ruokonen A, Leppäluoto J. The pituitary-thyroid axis in healthy men living under subarctic climatological conditions. J Endocrinol 2001;169:195- 203.

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