An enriched environment during adolescence reduced ADHD-related behaviors in SHR and SLA16 male rats

Environmental enrichment (EE) has emerged as a promising intervention capable of modulating behavior. The isogenic rat strains Spontaneously Hypertensive Rats (SHR) and SHR.LEW-(D4Rat76-D4Mgh11) (SLA16) share an identical genome, differing only in a specific region on chromosome 4. Despite this genetic similarity, these two strains exhibit notable behavioral differences, suggesting a potential influence of environmental and genetic factors. This study aimed to evaluate the effects of continuous EE (40 days, 8 different layouts) during adolescence on the behavior of SHR and SLA16 rat strains. A total of 48 male rats, aged 28 days, were assigned to four experimental groups: SHR-Standard Environment (SHR-SE), SHR-Enriched Environment (SHR-EE), SLA16-Standard Environment (SLA16-SE), and SLA16-Enriched Environment (SLA16-EE) and the following behavioral tests were conducted: Open Field (OF), Marble Burying (MB), Elevated Plus-Maze (EPM), Activity Cage (AC), Novel Object Recognition (NOR), and Plus Maze (PM). Environmental effects were observed in locomotion parameters in the OF, AC, and PM tests (EE < SE); in exploration of aversive areas in the OF and EPM tests (EE < SE); in stereotyped behavior in the MB test (EE < SE); in novelty preference in the NOR and AC tests (EE < SE); and in memory and attention parameters in the PM test (EE > SE). In conclusion, EE demonstrated beneficial effects on the behavior of SHR and SLA16 rat strains and may be considered a potential non-pharmacological intervention strategy for future evaluation in Attention-Deficit/Hyperactivity Disorder individuals.