Chronic sodium bromide relieves autistic-like deficits in the Oprm1 mouse model of autism and modulates the activity of serotonin and dopamine receptors in vitro

Chronic sodium bromide relieves autistic-like deficits in the Oprm1 mouse model of autism and modulates the activity of serotonin and dopamine receptors in vitro C. DERIEUX 1 , S. ROUX 1 , A. LEAUTE 1 , T. PLOUVIER 2 , J.A.J. BECKER 1 , J. LE MERRER 1 1 Déficits de Récompense, GPCRs et Sociabilité, Physiologie de la Reproduction et des Comportements, INRA UMR0085, CNRS UMR7247, Université de Tours, Inserm ; 37380 Nouzilly, France 2 Térali Innov, 37230 Fondettes, France Corresponding author : cecile.derieux@inra.fr Autism spectrum disorders (ASD) are complex neurodevelopmental diseases whose diagnosis lies on the detection of impaired social skills together with restricted and repetitive behavior and interests (DSM-5). Although the etiology of ASD remains mostly unknown, impaired excitation/inhibition ratio appears as a common mechanistic feature. Bromide ion is known to reduce hyperexcitability, possibly by competing with chloride ions at channels and transporters and may thus have therapeutic potential in ASD. Aims : We evaluated the therapeutic potential of bromide ion in the Oprm1 -/- mouse model of ASD and the molecular mechanisms involved in bromide treatment, notably effects on GPCRs. Methods : In vivo , we first assessed the effect of chronically administered sodium bromide on autistic-like behavioral deficits and performed RT-qPCR on brain structures known to be involved in ASD. In vitro , we evaluated the impact of bromide ion on G-protein mediated signaling of serotonin and dopamine receptors. Results : In vivo , sodium bromide (30 to 500 mg/Kg) dose-dependently improved social interaction and preference, reduced stereotypies and decreased anxiety. Bromide also impacts the expression of genes coding for some GPCRs, chloride transporters and GABA A subunits. In vitro , bromide behaves as a positive allosteric modulator of 5-HT 6 , 5-HT 7 and D1 receptors but not 5-HT 4 and D2 receptors. Conclusions : The beneficial effects of bromide administration in a genetic murine model of ASD and its impact on both gene expression and GPCR pharmacology predicts high translational potential in patients with autism, despite high heterogeneity in etiology and symptoms.