Corticosterone urinalysis and nicotinic receptor modulation in rats

Area of Science:

• Endocrinology
• Neuroscience
• Animal Physiology

Background:

• Current methods for measuring circulating corticosterone (CORT) in rats, such as plasma sampling, are invasive and can be stressful.
• Stressful procedures can confound results, impacting the accuracy of CORT level measurements.
• A non-invasive method is needed to accurately assess CORT levels in rats without introducing confounding stress.

Purpose of the Study:

• To investigate the feasibility of measuring corticosterone using non-invasive urine sampling in male rats.
• To assess the reliability of urinary corticosterone measurements through pharmacological and behavioral challenges.
• To explore the involvement of specific nicotinic receptor subtypes in modulating urinary corticosterone levels.

Main Methods:

• Male rats were administered nicotine (0.1-1mg/kg) or subjected to forced swim stress.
• Urinary corticosterone levels were measured at various time points post-administration/stress.
• Nicotinic receptor antagonists (mecamylamine) and subtype-specific agonists (TC-2559) were used to probe receptor involvement.

Main Results:

• Nicotine administration dose-dependently increased urinary corticosterone levels within 30-70 minutes, returning to basal levels by 6-24 hours.
• Urinary CORT elevations induced by nicotine were comparable to those from forced swim stress.
• Mecamylamine reversed nicotine-induced CORT increases, and the alpha(4)beta(2) agonist TC-2559 elevated CORT, while other ligands had no effect.

Conclusions:

• Urinary corticosterone sampling in rats is a feasible and robust non-invasive method for assessing CORT levels.
• This assay is sensitive to pharmacological and behavioral manipulations, validating its use in research.
• The findings suggest a role for specific nicotinic acetylcholine receptor subtypes in regulating corticosterone release.