Physiological control of pituitary hormone secretory-burst mass, frequency, and waveform: A statistical formulation and analysis

Daniel M. Keenan, Ferdinand Roelfsema, Nienke Biermasz, Johannes D. Veldhuis

Research output: Contribution to journalArticle

86 Scopus citations

Abstract

The present study investigates the time-varying control of pituitary hormone secretion over the day and night (D/N). To this end, we implemented an analytical platform designed to reconstruct simultaneously 1) basal (nonpulsatile) secretion, 2) single or dual secretory-burst waveforms, 3) random effects on burst amplitude, 4) stochastic pulse-renewal properties, 5) biexponential elimination kinetics, and 6) experimental uncertainty. The statistical solution is conditioned on a priori pulse-onset times, which are estimated in the first stage. Primary data composed of thyrotropin (TSH) concentrations were monitored over 24 h in 27 healthy adults. According to statistical criteria, 21/27 profiles favored a dual compared with single secretory-burst waveform. An objectively defined waveform change point (D/N boundary) emerged at 2046 (±23 min), after which 1) the mass of TSH released per burst increases by 2.1-fold (P < 0.001), 2) TSH secretory-burst frequency rises by 1.2-fold (P < 0.001), 3) the latency to maximal TSH secretion within a burst decreases by 67% (P < 0.001), 4) variability in secretory-burst shape diminishes by 50% (P < 0.001), and 5) basal TSH secretion declines by 17% (P < 0.002). In contrast, the regularity of successive burst times and the slow-phase half-life are stable. In conclusion, nycthemeral mechanisms govern TSH secretory-burst mass, frequency, waveform, and variability but not evidently TSH elimination kinetics or the pulse-timing process. Further studies will be required to assess the generality of the foregoing distinctive control mechanisms in other hypothalamo-pituitary axes.

Original languageEnglish (US)
Pages (from-to)R664-R673
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume285
Issue number3 54-3
DOIs
StatePublished - Sep 1 2003

Keywords

  • Hypothalamus
  • Pulsatility
  • Secretion
  • Thyrotrope

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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