Modest environmental enrichment: Effect on a radial maze validation and well being of rats

Abstract

Our 8-arm radial maze test was validated to demonstrate memory deficits in rats treated with the muscarinic antagonist scopolamine hydro bromide (SHB, 0.1 mg/kg, i.p.). To improve quality of life, we enriched the environment of single housing rats. Enrichment procedures were chosen to increase the animals' well being without disturbing a lot the results of behavioural tests. It is modest, consisting of a plastic tube and corn chips. Enriched environment (EE) and Non-enriched Environment (NE) animals' performances were compared during the 8-arms radial maze validation. Enrichment procedures were chosen to increase the animals' well being without disturbing the results of behavioural tests. The impact of our enrichment conditions was then evaluated on the general behaviour of rats, weight evolution and results of a plus maze anxiety test. Results showed a deficit and a delay in learning for SHB-treated animals, and a general time-dependent learning effect, validating our test. No effect of enrichment on negative control animals was observed. For SHB-treated animals, enrichment increased performances during learning task and accentuated the deficits in test task. Exploratory behaviour of enriched animals seemed to be increased. A general amelioration of well being for EE animals was found (stable weight). We conclude that our enrichment allows increasing exploratory behaviour not modifying radial maze sensitivity using a simple modification of our protocol (limitation to 16 visits/trial). We decided to generalise this enrichment to all our studies, given its simplicity and obtained benefits.