Sodium butyrate rescues long-term neurodevelopmental deficits following perinatal methadone exposure

Prenatal opioid exposure (POE) induces long-term neurodevelopmental, behavioral and cognitive deficits for which no targeted treatments are available. The mechanisms underlying POE deficits are poorly understood, but have been linked to a range of central, peripheral, and enteric nervous system changes. Emerging evidence indicates that maternal microbiota changes may also contribute to these long-term offspring deficits.

Here we test the efficacy of the short-chain fatty acid sodium butyrate (NaB) to mitigate POE-induced deficits in a rat model. 26 pregnant rat dams received methadone via mini-osmotic pump and/or NaB via drinking water in a 2 × 2 design. We then performed a battery of developmental, behavioral, microbiome and neurobiological assessments across offspring infancy, adolescence and adulthood. Both methadone and sodium butyrate treatments altered dam microbiota composition and function: notably methadone disrupted microbial gene expression of enzymes critical for butyrate production and reduced faecal butyric acid levels.

In pups, methadone increased infant gut barrier permeability that was reversed with NaB, and induced infant microbial enzymatic disruption that resolved in adulthood. POE induced anxiety-like behavior in adolescence, and adulthood working spatial memory and attentional processing deficits that were partially rescued by prenatal NaB treatment. POE decreased myelination in the hippocampus, and this was partially reversed by NaB.

Together, these results highlight the role for the microbiota-gut-brain axis in animal models of POE. Furthermore, they provide evidence for NaB as a simple yet effective treatment to significantly improve the outcomes of children born with POE. The authors acknowledge use of facilities in the Katharine Gaus Light Microscopy Facility at Mark Wainwright Analytical Centre for sample paraffin embedding and the Ramaciotti Centre for Genomics, UNSW for sequencing of the microbiome samples and Dovile Anderson from the Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Australia who ran the SCFA analysis.

Experiments were performed on the UNSW Compute Cluster Katana (https://doi.org/10.26190/669X-A286). All timelines, schematics and explanatory figures were produced with Biorender.com. We would like to thank Melissa J.

Bebbington for her invaluable assistance with immunofluorescence techniques. This research was supported by an NHMRC Ideas Grant 2023/GNT2027729 to KC, JVD, JO, CO and AW. School of Psychology, Faculty of Science, University of New South Wales, Sydney, NSW, Australia Isobel A.