Comparison of hair steroid levels among Wistar rats exposed to different environmental enrichment settings

Vet World Vol.17 December-2024 Article - 4

Research Article

Veterinary World, 17(12): 2731-2735

https://doi.org/10.14202/vetworld.2024.2731-2735

Alberto Elmi^1,2†, Niccolò I. Vannetti^1†, Viola Galligioni³, Nadia Govoni¹, Camilla Aniballi¹, José M. Sánchez-Morgado⁴, Maria L. Bacci¹ and Domenico Ventrella¹

1. Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, Bologna, Italy.
2. Department of Veterinary Sciences, University of Pisa, Pisa, Italy.
3. Netherlands Institute for Neuroscience, KNAW, Amsterdam, the Netherlands.
4. Bioresearch and Veterinary Services, The University of Edinburgh, Edinburgh, United Kingdom.
†These authors contributed equally to this work and share first authorship

Background and Aim: Environmental enrichment (EE) is a pivotal tool for creating ideal housing conditions that allow animals to fully display their ethograms. At the micro-environmental level, they should elicit cognitive and social responses and increase physical activities. Hair steroids may be among the best biomarkers to evaluate the effects of prolonged exposure to different enrichments because they are non-invasive and provide information regarding a longer period. This study aimed to compare the hair steroid profiles, specifically corticosterone, cortisol, and dehydroepiandrosterone (DHEA), of Wistar rats exposed to two different EE settings.

Materials and Methods: Twenty (n = 20) outbred Wistar rats were enrolled in this study. First hair collection (T0) was performed 3 days before weaning (at 28 days of life), and then Wistar rats were randomly divided into two equal groups with a sex ratio of 1:1: standard EE group, provided with one rat tunnel, and extra EE group, provided with an additional tunnel hanging from the top of the cage. Environmental conditions were 20^°C–24^°C, 45%–65% relative humidity, and a 12:12 dark/light cycle, with water and pelleted diet ad libitum. The rats were housed in ventilated cages with poplar bedding and nesting material. Hair was sampled again after 3 months (T1). Steroids were quantified using radioimmunoassay or enzyme-linked immunosorbent assay after methanol extraction.

Results: Cortisol was not quantifiable, while corticosterone and DHEA were. After 3 months of exposure (T1), no differences were noted between the experimental groups. On data categorization per sex, females showed higher levels of all steroids than males. In males, the extra EE group had higher corticosterone levels.

Conclusion: This study showed that corticosterone and DHEA are quantifiable in rats’ hair, yet bigger datasets are needed to better understand the physiological levels of these hormones in such a matrix. Different enrichment settings induced differences between and within sex.

Keywords: 3Rs, biomarker, environmental enrichment, Rattus norvegicus, refinement, steroid, welfare.

How to cite this article: Elmi A, Vannetti NI, Galligioni V, Govoni N, Aniballi C, Sánchez-Morgado JM, Bacci ML, and Ventrella D (2024) Comparison of hair steroid levels among Wistar rats exposed to different environmental enrichment settings, Veterinary World, 17(12): 2731–2735.

Received: 2024-07-04 Accepted: 2024-11-12 Published online: 2024-12-06

Corresponding author: Alberto Elmi E-mail: alberto.elmi@unipi.it

DOI: 10.14202/vetworld.2024.2731-2735

Copyright: Elmi, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/ by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.