Increased anxiety-like behaviour and altered GABAergic system in the amygdala and cerebellum of VPA rats - An animal model of autism

Abstract

Anxiety is one of the associated symptoms of autism spectrum disorder. According to the literature, increases in anxiety are accompanied by GABAergic system deregulation. The aim of our study, performed using an animal model of autism in the form of rats prenatally treated with valproic acid (VPA rats), was to investigate changes in anxiety-like behaviour and the gene expression of molecules that control levels of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) in the brain. Anxiety-like behaviours were investigated using zone preferences in the open field test. The levels of the 65 and 67kDa enzymes of l-glutamic acid decarboxylase (GAD) mRNAs and type 1 GABA transporter (GAT1) were evaluated in the amygdala, as well as GABA producing enzymes in the cortex layer of the cerebellum. Our research showed that adult VPA rats spent less time in the inner zone of the testing chamber and more time in the outer zone of the testing chamber in the open field test. We also found that adult VPA rats had increased expression of GAT1 in the amygdala, as well as decreased levels of GAD65 and GAD67 mRNA in the cerebellum compared to control animals. These findings support the existence of a relationship between increased anxiety-like behaviour and changes in the regulation of the GABAergic system in VPA rats.

Keywords: Animal model; Anxiety; Autism; GABA; VPA rats.