<prompt> Hype ram monaemia inhib it TCA cycle by depleting: PGI June 2009Oxaloacetatea-ketoglutarateCitrateSuccinyl Co-A  <response>: Ans: B a-ketoglutarate ; Harper 29th168HyperammonaemiaQ reduce mitochondrial pool ofa-ketoglu tarate consequently depresses the TCA cycle, affecting the cellular respiration- Chatterjea Shinde 7th447Hyperammonoemia NH3 concentration enhance amination of a-KGQ, an intermediate in TCA cycle to form glutamate in brain. This reduce a-KG pool in mitochondria.NH3 concentration enhance glutamine formation from glutamate thus reduces brain-cell pool of glutamic acid. Hence there is ed formation of inhibitory neurotransmitter GABA g-amino butyric acidRise in brain glutamine cause increase in tryptophan concentration in brain cells, which leads to abnormal increase in synthesis of serotonin a neurotransmitter.Cause mental retardation5Acquired hyperammonoemia may be due to hepatitis alcohlasmToxic effects of NH. on the brain are dt impairment of ATP formationAlso know: Metabolic fate of NH3 in body:Majority of NH3 is converted to urea urea cycle Q Formation of glutamine Amination of a-keto add to form a-amino acid 