(P11-018-25) Study Protocol: Neuro Imaging to Investigate the Effect of Docosahexaenoic Acid Onneurotransmitter Switch in Neonatal Brain

Objectives: Medial prefrontal cortex (mPFC) is often diagnosed as an affected brain region with autism spectrum disorders (ASD). A low ratio of gamma aminobutyric acid (GABA) to glutamate has been reported in inhibitory neurons such as in parvalbumin (PV) and cholecystokinin (CCK). Early-life exposure to environmental insults such as enhanced immune responses of pregnant mothers for infections causes short-term neurotransmitter switches in the early postnatal brain. However behaviour changes are absent during these postnatal periods. Those epigenetic changes in offspring predispose them to later development of ASD via low GABA/glutamate in mPFC. Preventing neurotransmitter switches at early stages of brain development can prevent development of ASD in adulthood via maintaining balanced GABA/Glutamate mRNA in mPFC. Docosahexaenoic acid (DHA) is critical for neonatal brain development. Neonatal brain demands a high DHA, however, endogenous synthesis is low, thus requiring significant dependence on mammary milk. We optimized mRNA neurocircuitry imaging to measure multiple mRNAs in a single brain section. Neuroimaging of mRNAs allows us to identify early changes to the brain neurocircuitry even before beginning to see the changes to behaviour.

Objective: how lack of DHA affects GABA synthesizing enzyme (GAD67) to vesicular glutamate transporter expression (VGLUT) mRNAs ratio in PV and CCK neurons located in mPFC of early postnatal brain. 

Methods: 16 C57BL6 dams will receive intraperitoneal injection of Polyinosinic:polycytidylic acid at gestational day 12. Dams will start receiving 1) DHA (300 mg/d) (n=8) in regular chow diet, 2) Control (n=8) regular chow diet on postnatal D0. Pups will be sacrificed at postnatal D25 and extracted brains will be neuroimage to measure GAD67 and VGLUT mRNA expressions in PV and CCK neurons. Immunostaining will produce 3 colours in a single brain section; Channel 1: PV (yellow) or CCK, Channel 2: GAD67 (green), Channel 3:VGLUT (red) mRNA.

Results: N/A

Conclusions: Changes to mRNAs of neurocircuitry are prodromal to behaviour alterations. Identifying such modifications before beginning to see behaviour changes are critical to prevent and manage later onset of neurological disorders. Pups of dams fed Control diet will have low GAD67 / VGLUT in PV and CCK neurons of mPFC compared to those pups of dams fed DHA diet.

Funding Sources: Not decided