Effect of FLA-63, p-chlorophenylalanine and pimozide on the metabolism and incorporation of 3H-thymidine in the brain of rat pups.

The aim of the work is to learn if norepinephrine, dopamine or serotonin have a specific role in the maintenance of normal cell proliferation in the brain of developing rats. Between 2-24 hr after the administration of FLA-63 the incorporation rate of labelled thymidine into the DNA of 10-day-old rat brain was reduced, parallel with the decrease of tissue norepinephrine level. A similar inhibition was observed under the effect of p-chlorophenylalanine, 3-72 hr after administration. The weight gain of the rat pups was also reduced by this substance. Pimozide had no influence on 3H-thymidine incorporation rate. FLA-63 and p-chlorophenylalanine significantly impaired the transport of the radioactive precursor between blood and brain tissue and its phosphorylation to thymidine nucleotides. Tissue norepinephrine and serotonin levels are considered to play regulatory role in early postnatal cell proliferation in the rat brain.