Project II- Impact of Hypoxia-Ischemia and/or inflammation on Metabolism in Cerebellum

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Neonatal hypoxia-ischemia (H/I) leads to rapid energy failure in cortical, subcortical and hippocampal regions due to lack of oxygen and glucose delivery to brain. This is followed by a transient normalization during reperfusion and a later secondary energy failure (~2-6 hours after H/I) that ultimately leads to brain injury, and poor neurodevelopmental outcome. Inflammation occurring prior to H/I can exacerbate injury. Acute alterations in metabolism and prolonged metabolic dysregulation after neonatal H/I leave the brain vulnerable and unable to support processes essential for normal development. We will use a well-characterized model of perinatal H/I at term (postnatal (PN) day 10 rat pup) with and without prior inflammation. The effects of H/I on cerebellum have not been carefully explored even though the rapidly developing cerebellum is particularly vulnerable to inflammation and perinatal injury. We will combine high field 1H-NMR and 13C-NMR spectroscopy of energy metabolism and neurotransmitter synthesis with matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) determination of metabolites, lipids, proteins in specific layers of the cerebellum. Our studies will be the first determination of alterations in metabolism via astrocyte and neuron specific pathways and synthesis of glutamate and GABA in cerebellum after H/I. Molecular and metabolic alterations and long- term functional outcomes will determine the therapeutic potential of hypothermia and drug therapy. We hypothesize that neonatal H/I leads to energy failure in the cerebellum that contributes to impaired function of brain cells including acute and long-term alterations in energy metabolism and neurotransmitter synthesis. We hypothesize that the combined effect of inflammation and H/I exacerbates cerebellar damage and dysregulated metabolism in male and female brain. Our Specific Aims test these hypotheses: 1. Determine the effect of H/I at PN10 with and without prior inflammation on energy metabolism in cerebellum of male and female rat pups. 2. Determine the alterations in neurotransmitters, metabolites, lipids and proteins in Purkinje, molecular and granule cell layers, deep nuclei and white matter of the cerebellum of male and female pups after H/I with and without prior inflammation. 3. Determine the protective effect of hypothermia, choline and ceftriaxone alone, and these compounds in combination with hypothermia against changes in neuronal and glial metabolism and specific molecular changes in the Purkinje, molecular and granule cell layers, deep nuclei and myelin. Novel, clinically relevant information about the timing and targets of injury and alterations in neuron and astrocyte specific metabolic pathways in brain and alterations of metabolites, nucleotides, membrane and signaling lipids, and proteins in cerebellar layers and deep nuclei will be obtained using the unique combination of 1H- NMR and 13C-NMR in conjunction with MALDI-MSI and LC/MS-MS for profiling the changes after H/I with and without inflammation, inflammation alone and response to neuroprotective therapy.