Validation of a method for quantifying urinary C-peptide in platyrrhine monkeys

Area of Science:

• Primate physiology
• Metabolic research
• Biomarker validation

Background:

• Urinary C-peptide (UCP) is an established non-invasive biomarker for insulin and energy balance in catarrhine primates.
• Previous validation studies for UCP as an energy expenditure measure have not included platyrrhine primates.
• Divergent evolution in insulin gene organization necessitates specific validation for platyrrhines.

Purpose of the Study:

• To evaluate and validate a method for quantifying urinary C-peptide (UCP) in platyrrhine primates.
• To assess UCP as a physiological measure of energy expenditure in tufted capuchins (Sapajus apella).

Main Methods:

• Opportunistic collection of urine samples from laboratory-housed tufted capuchins during exercise.
• Measurement of UCP concentrations using a commercial C-peptide radioimmunoassay.
• Analysis of UCP levels before and after exercise, correlating with exercise intensity and speed.

Main Results:

• Average UCP concentrations were significantly lower post-exercise (0.34 ng/mL decrease).
• Higher exercise speeds correlated with greater UCP concentration decreases, indicating increased energy expenditure.
• Serial dilution assays confirmed the precision and reliability of the UCP measurement method.

Conclusions:

• Biological validation of a commercial radioimmunoassay for quantifying UCP in platyrrhines.
• UCP serves as a reliable non-invasive biomarker for assessing energy expenditure in tufted capuchins.
• This method advances the study of energy balance in platyrrhine primates.