Differential effects of short-term fasting on pulsatile thyrotropin, gonadotropin, and α-subunit secretion in healthy men - A clinical research center study

M. H. Samuels, P. Kramer

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

In healthy subjects, short term fasting suppresses the hypothalamic- pituitary-thyroid and hypothalamic-pituitary-gonadal (HPG) axes, with decreased serum levels of TSH and LH. However, effects of fasting on pulsatile release of TSH, LH, FSH, and α-subunit are less clear. Eleven healthy young men each underwent two 2-day studies: a baseline study during normal caloric intake and a fasting study during 56 h of caloric deprivation. During the final 24 h of each study, blood samples were drawn every 15 min for measurement of serum TSH, LH, FSH, and α-subunit pulses. Fifty-six hours of fasting caused a 50% suppression of mean TSH levels and TSH pulse amplitude, without altering TSH pulse frequency. Nocturnal TSH pulse amplitude decreased by 60%, with abolition of the usual nocturnal TSH surge. Fasting suppressed mean LH levels and LH pulse amplitude by 30%, without affecting LH pulse frequency. In contrast, mean FSH levels only decreased by 13%, without changes in FSH pulse parameters, whereas mean α-subunit levels and pulse amplitude decreased by 20%. These data show that short term fasting has a greater suppressive effect on the hypothalamic-pituitary-thyroid axis than on the HPG axis. Within the HPG axis, FSH is more resistant to fasting- induced suppression than LH, implying discordant regulation of the two gonadotropins during nutritional deprivation. α-Subunit suppression during fasting appears to parallel that seen for LH.

Original languageEnglish (US)
Pages (from-to)32-36
Number of pages5
JournalJournal of Clinical Endocrinology and Metabolism
Volume81
Issue number1
DOIs
StatePublished - 1996

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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