Acceleration of the biosynthesis of rat striatal dopamine by incubation and by administration of gamma-butyrolactone.

The concentration of dopamine in striatal slices obtained from rats treated with an MAO inhibitor was increased significantly by a 50-minute incubation in oxygenated Krebs buffer at 37 degrees C. Administration of alpha-methyl-p-tyrosine did not antagonize this small increase in dopamine. The extent of the incubation-induced increase was much greater in tissue obtained from control rats and was also greater than that resulting from the intraperitoneal administration of gamma-butyrolactone (GBL). Prior administration of alpha-methyl-p-tyrosine, d-amphetamine, apomorphine, or lergotrile significantly antagonized the increases in striatal dopamine levels induced by GBL administration or by incubation of striatal slices obtained from control rats. The prior administration of phenylethylamine, however, antagonized the incubation-induced, but not the GBL-induced, increase in striatal dopamine. In conclusion, the effect of incubating striatal slices on their dopamine levels was similar to that of administering GBL in that the incubation enhanced the activity of tyrosine hydroxylase that in turn produced an accelerated synthesis of dopamine.