Measuring corticosterone concentrations over a physiological dynamic range in female rats

Area of Science:

• Endocrinology
• Animal Behavior
• Assay Development

Background:

• Accurate measurement of plasma corticosterone, a key rodent stress hormone, is vital for research.
• Enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) are common methods, but exhibit variability.
• Previous comparisons focused on technical aspects, not detection of acute stress responses.

Purpose of the Study:

• To compare the efficacy of four commercial corticosterone assays (3 ELISA, 1 RIA) in detecting acute stress-induced changes.
• To evaluate assay performance across a dynamic range of baseline and stress corticosterone concentrations.
• To determine how assay choice impacts the interpretation of stress response data.

Main Methods:

• Utilized the forced swim test, a standard acute stressor in rodents.
• Compared three ELISA kits and one RIA kit for corticosterone quantification.
• Analyzed plasma corticosterone levels in rats under baseline and acute stress conditions.

Main Results:

• All assays showed relative differences, but only two detected statistically significant increases in corticosterone post-stress.
• The Enzo Life Sciences ELISA kit showed the largest percent increase in corticosterone.
• The MP Biomedicals RIA kit detected significant increases and reported higher baseline and stress corticosterone concentrations.

Conclusions:

• Assay selection significantly impacts the ability to detect acute stress-induced changes in plasma corticosterone.
• Differences in assay sensitivity and range affect the interpretation of rodent stress response data.
• Researchers must carefully consider assay characteristics when studying corticosterone dynamics.