Action of S-adenosyl-L-homocysteine on the metabolism of dopamine, norepinephrine and serotonin in rat brain.

S-Adenosylhomocysteine (SAH) (0.1 to 30 mg/kg/i.p.) increased 3H-norepinephrine synthesis from 3H-tyrosine in the rat brain stem and mid brain, but did not alter its tissular level. It decreased both the serotonin level and the formation of 3H-serotonin from 3H-tryptophan and increased the formation of 3H-5hydroxyindolacetic acid. Its effects began 1 hr after administration and was still present 6 hr later. It did not alter dopamine metabolism. A correlation between the hynotic effect of SAH and the modification of the metabolism of cerebral monoamines was pointed out.