Effects of reserpine and monoamine oxidase inhibition on the levels of amino acids in sensory ganglia, sympathetic ganglia and spinal cord

Reserpine and pargyline, which are known to alter monoamine metabolism, were found to affect the levels of amino acids in neuronal structures of the cat supplied by noradrenergic terminals (Gasserian, spinal and sympathetic ganglia and spinal cord); the sympathetic ganglia also have sympathetic ganglionic perikarya and dopamine-containing cells. In particular reserpine significantly decreased the levels of glutamic acid as alanine-glycine in dorsal root ganglia and Gasserian ganglia as well as the glutamic acid in the sympathetic ganglia; it lowered the levels of glutamic and aspartic acid in the spinal cord. Pargyline significantly decreased the levels of glutamic acid, glutamine, aspartic acid and alanine-glycine in the dorsal root ganglia; it had no effect on the sympathetic ganglia. The results are discussed with the suggestion that the lowered levels of amino acids observed in the dorsal root ganglia after the pharmacological treatment may be reflected in the spinal terminals of the dorsal root fibers. Further, a direct interaction of the drugs with the spinal noradrenergic terminals of supraspinal neurons is also considered. Finally, biochemical mechanisms by which metabolism of catecholamines and amino acids may be interrelated are presented.