Amino acid neurotransmission

Question 1

Ketogenic AAs

Answer 1

Lysine and leucine

yield acetyl-CoA, or acetoacetyl-CoA

cannot produce metabolites that convert to glucose

Question 2

Glucogenic AAs

Answer 2

Alanine, Arginine, Asparagine, Aspartate, Cysteine, Glutamate, Glycine, Histidine, Methionine, Proline, Serine, and Valine

they form pyruvate and krebs cycle metabolites that can be used to produce glucose

Question 3

Glucogenic and ketogenic AAs

Answer 3

Isoleucine, Phenylalanine, Tryptophan, Tyrosine and Threonine

Some metabolites become glucose, others yield acetyl-CoA, or aectoacetyl-CoA

Question 4

Glutamate synthesis, metabolism and conversion to GABA

Answer 4

Identified in the brain in 1935.
present in high concs.
initially was thought to serve metabolic role

Glutamine converted to glutamate by glutamate synthase. Glutamate converted to glutamine by glutaminase.

Glutamate converted to GABA by glutamate decarboxylase.

Glutamate converted to alpha ketoglutyrate by aminotransferase

glutathione is a cysteine and glutamate conjugation.

Question 5

Watkins and classifying glutamate as NT

Answer 5

In 1954, injection of glutamate to brain was found to cause seizures

Watkins found that glutamate caused a depolarisation, and thus believing it was NT.

was then retracted as an NT because they believed it had non-specific effect as it stimulated Renshaw cells (ACh neurones) they glutamate neurones innervate the Renshaw cells, modulating it

was found to be an NT, having role in brain dysfunction, particularly in epilepsy

the lack of effective antagonists to glutamate was a considerable hindrance for establishing glutamate as a NT.

Question 6

NMDA and stereospecificity

Answer 6

NM(Dextro)A was more potent than levorotatory form. Therefore the site of action could exhibit stereo-selectivity, and thus implying discrete sites of binding.