Interrelated changes of amino acids in the retina and optic tectum of a marine fish with alterations of illuminating conditions.

Examination of interrelated changes in the concentrations of 'clusters' of amino acids provides evidence that individual amino acid levels in the tissues cannot be considered to vary independently. Such variations are observed when the CNS at 'rest' is stimulated. Alterations in taurine cause changes in glutamic acid and also modify its anatomically related compartmentalized metabolism. Similar interdependent modifications may be indicated for the concentrations of 3 biochemically related neutral amino acids: threonine, serine and glycine. With specific reference to the fish optic tectum and retina, certain differences and coincidences in the regulation of GABA and glycine have also been uncovered. Finally, many of the findings presented here are closely analogous to results obtained when comparing normal and epileptic mammalian tissues. Possibly, this analogy can be attributed to the fact that the physiological states so far investigated, from the most simplistic point of view, represent extreme variations of nervous tissue excitation.