Metabolic and Behavioral Features of Acute Hyperpurinergia and the Connection to Autism Spectrum Disorder

Abstract

Background. Since 2012, studies in mice, rats, and humans have suggested that abnormalities in purinergic signaling may be a final common pathway for many genetic and environmental causes of autism spectrum disorder (ASD). The current study in mice was conducted to characterize the bioenergetic, metabolomic, breathomic, and behavioral features of acute hyperpurinergia triggered by systemic injection of the purinergic agonist and danger signal, extracellular ATP (eATP). Methods. Responses were studied in C57BL/6J mice with ASD-like behaviors in the maternal immune activation (MIA) model and controls. Basal metabolic rates, respiratory exchange ratios (RER = VCO2/VO2), and locomotor activity were measured in CLAMS cages. Plasma metabolomics measured 401 metabolites. Breathomics measured 98 volatile organic compounds. Results. A 0.5 µmol/g dose of ATP dropped whole body oxygen consumption by 74% ± 6% (mean ± SEM, 5,303 to 1,382 ml/kg/hr, p<0.0001) and rectal temperature by 6.2˚ ± 0.3˚C (p<0.0001) in 30 minutes. Over 200 metabolites from 37 different biochemical pathways where changed. MIA animals were hypersensitive to the metabolic and behavioral responses triggered by eATP and poly(IC). Breathomic and metabolomic analysis revealed changes in folate-methylation-1-carbon, purines, pyrimidines, acyl-carnitines, glycolysis, aromatic and branch-chain amino acids, Krebs cycle, glutathione, urea cycle, phospholipids, sphingolipids, eicosanoids, cholesterol, bile acids, vitamins, and microbiome metabolism similar to children with ASD. Limitations. The responses to ATP were studied in only a single genetic strain of mice (C57BL/6J). Although similar to metabolic results reported in FVB mice and a small clinical trial in children with ASD, the generalizability of these results to larger studies in humans is unknown. The chronic effects of repeated postnatal ATP exposures were not tested. Conclusions. Acute hyperpurinergia produced metabolic and behavioral changes in mice that were similar to those found in children with ASD. These behaviors and metabolic changes were associated with mitochondrial functional changes that were profound but reversible.