Advances in the field of mitochondrial biology has demonstrated that mitochondrial activities go beyond regulation of ATP production and cell death. Indeed, in the immature brain, mitochondria appear to be commanders of inflammation, synaptic development and connectivity, and possibly repair 1.
The overall aim of the project is to establish the developmental and endocrine regulation of mitochondrial function in the brain. This will be achieved by answering the following two questions:
Does mitochondrial function in different brain regions change during development and with ageing?
Do thyroid hormones modulate cerebral mitochondrial function during development?
Answering these questions will provide insight into the role of mitochondria in brain development and ageing, and have important implications for neurological disease.
Aim 1: The experiments will be carried out on time-dated twin pregnant Welsh Mountain ewes between 100 and 145 days of gestation (term ~145 days), and adult offspring from 9 to 12 months of age. Tissue samples from different brain regions will be collected. Mitochondrial respiration will be measured using a substrate-uncoupler-inhibitor titration protocol and an Oroboros Oxygraph respirometer. Mitochondrial morphology and brain architecture will be assessed in archived samples using immunohistochemical and stereological techniques. Mitochondrial density, biogenesis, oxidative capacity and gene transcription regulation, tissue indicators of oxidative stress, and senescence markers, will be quantified in archived samples using Western blotting or RT-PCR. This part of the study will establish developmental and age-related changes in mitochondria function.
Aim 2: Under general anaesthesia at 100-105 days of gestation one fetus of each pair of twins will be thyroidectomised while the other is sham-operated. Tissue samples will be collected at 125-130 and 140-145 days, and analysed as in Aim 1. By comparison to Aim 1, this part of the study will demonstrate whether thyroid hormones regulate cerebral mitochondria function during development.
1. Hagberg, H., Mallard, C., Rousset, C. I. & Thornton, C. Mitochondria: hub of injury responses in the developing brain. Lancet Neurol 13, 217-232, (2014).