Validation of an ELISA kit to measure allopregnanolone in human and equine hair

Abstract

In humans, allopregnanolone plays important roles in a number of different neurodegenerative disorders, and it has been proposed for use in some therapies. Horses are commonly used as animal models for human neurodegenerative diseases, mental and behavioral disorders, and neuropsychiatric disorders, and there is interest in using hair as a biological sample to study hormones in these conditions. We validated the use of a commercial ELISA kit (DetectX allopregnanolone kit; Arbor Assays), which was designed for serum, plasma, feces, urine, and tissue samples, to assess allopregnanolone in hair samples from 30 humans and 63 horses. The ELISA kit had good precision (intra- and inter-assay CVs: 6.4% and 11.0% for equine hair; 7.3% and 11.0% for human hair, respectively), sensitivity (50.4 pg/mL for both equine and human hair), and accuracy (parallelism and recovery tests) in determining allopregnanolone concentrations in hair from both species. The allopregnanolone concentrations in human hair were 7.3-79.1 pg/mg; the concentrations were 286 ± 141 pg/mg (x̄ ± SD) in mares on the day of parturition and 16.9 ± 5.5 pg/mg in nonpregnant mares. The DetectX ELISA kit offered a simple and accessible analysis of allopregnanolone in human and equine hair samples.

Keywords: allopregnanolone; hair; horses; humans; method validation.

Figure 1.

Graphical plot for the parallelism obtained by the DetectX ELISA kit (Arbor Assays) on equine hair. The relationship between equine hair allopregnanolone concentrations and the standard allopregnanolone curve is given by the equation y = 0.96x + 1.16.

Figure 2.

Graphical plot for the parallelism obtained by the DetectX ELISA kit (Arbor Assays) on human hair. The relationship between human hair allopregnanolone concentrations and the standard allopregnanolone curve is given by the equation y = 1.05x–1.13.