The relationship between insulin-like growth factor-I, adiposity, and aging

Area of Science:

• Endocrinology
• Gerontology
• Human Physiology

Background:

• Aging is characterized by increased body fat and reduced growth hormone (GH) secretion.
• Insulin-like growth factor-I (IGF-I) serves as a key indicator of GH activity.
• Understanding the interplay between aging, body composition, and IGF-I is crucial for metabolic health.

Purpose of the Study:

• To investigate the relationship between plasma IGF-I levels and anthropometric measures of body fat in a diverse age group.
• To determine if age and body fat independently influence IGF-I concentrations.
• To explore potential sex-specific differences in these associations.

Main Methods:

• Assessed somatic and biochemical nutritional indices in 107 healthy adult subjects (ages 17-83).
• Measured plasma IGF-I levels.
• Utilized correlation and multiple regression analyses to examine relationships between IGF-I, age, and body fat indices (BMI, triceps skinfold, body weight).

Main Results:

• Plasma IGF-I showed a significant negative correlation with age in both males and females.
• In males, IGF-I negatively correlated with body mass index (BMI), triceps skinfold (TSF), and body weight, independent of age.
• These adiposity-IGF-I correlations were not significant in females.

Conclusions:

• Adiposity and aging are independently associated with decreased plasma IGF-I concentrations.
• The decline in IGF-I with aging occurs in both sexes, but its association with increased adiposity is primarily observed in males.
• Sex differences in gonadal steroids may interact with declining GH secretion to influence age-related obesity development in males.