The Good, the Bad and the Plasticity Genes: The Role of both Positive and Negative Environmental Factors and the SERT KO Genotype on the Development of ASD-Like Symptoms in a Rodent Model

Abstract

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder with a number of contributing genetic and environmental factors. While a number of studies have looked at the negative environmental factors underpinning ASD, few have investigated the ameliorating effects of a combination of positive environmental treatments and genetic factors. The current study investigated whether 24 hours of maternal deprivation (MD, constituting a negative environment) on PND9, in combination with the serotonin transporter knockout (SERT KO) genotype would increase the autistic-like characteristics of male Wistar rats, and additionally, whether early handling (EH, constituting a positive environment) from PND2-14 in combination with the same genotype would decrease these behaviours. Five experiments were used: social interaction, social approach and avoidance, scent marking, hole dipping and reversal learning. The results showed that SERT KO MD rats have autistic-like social impairments, while the SERT KO EH rats show improvements on social and communicative tasks, indicating that, in some behavioural measures, both positive and negative environmental factors have a significant influence on the SERT KO genotype. These results highlight the importance of serotonin and early-life stress in the development of ASD, as well as the role of positive environmental factors in the treatment of this disorder.