Physiological parameters regulating circulating levels of the IGFBP-4/Stanniocalcin-2/PAPP-A axis

Area of Science:

• Endocrinology
• Human Physiology
• Biochemistry

Background:

• Circulating levels of the Insulin Growth Factor Binding Protein 4 (IGFBP-4), Stanniocalcin-2 (STC-2), and Pregnancy-Associated Plasma Protein-A (PAPP-A) axis (ISPa) are implicated in various physiological functions.
• Predictors for these circulating levels remain largely uncharacterized in healthy human populations.

Purpose of the Study:

• To identify anthropometric and biochemical parameters associated with ISPa serum levels cross-sectionally.
• To investigate the day-night variation of ISPa.
• To examine ISPa regulation in response to mixed meal ingestion and aerobic exercise.

Main Methods:

• Cross-sectional evaluation of 122 healthy individuals.
• Subgroup analysis involving standardized mixed meal ingestion (125mL or 250mL) and 30-minute aerobic exercise.
• Day-night rhythm studies to assess diurnal variations.
• Measurement of total and intact IGFBP-4, STC-2, and PAPP-A serum levels.

Main Results:

• Serum total IGFBP-4 was predicted by PAPP-A and female gender. Intact IGFBP-4 correlated with creatinine. STC-2 levels were inversely associated with height and positively with female gender and body fat percentage.
• PAPP-A levels decreased post-meal, and total IGFBP-4 decreased after a 250mL meal. Exercise significantly increased STC-2 and PAPP-A levels.
• Intact and total IGFBP-4 exhibited a cortisol-like diurnal variation pattern.

Conclusions:

• This study provides novel insights into the anthropometric and physiological factors modulating ISPa serum levels in healthy humans.
• Identified predictors include gender, body composition, creatinine, and physiological stimuli like meals and exercise.
• The diurnal rhythm of IGFBP-4 is highlighted, suggesting complex regulatory mechanisms.