Regional changes in brain catecholamine content following administration of guanethidine to neonatal rats.

Norepinephrine(NE), dopamine(DA) and serotonin(5-hydroxytryptamine, 5-HT) contents were estimated in the different regions of the developing rat brain following guanethidine injection at the neonatal period for the purpose of determining the influence of guanethidine on development of the monoamine neuron in the brain. Despite a nonsignificant change in the weights of all regions of the brain, guanethidine caused a significant reduction of NE content in the limbic-striatum at day 7 and 30 and an increase in mesencephalon-ponsmedulla at day 30. DA concentration in the limbic-striatum at day 7, 14 and 30 and in the neocortex at day 7 showed a decrease with guanethedine treatment. The change in 5-HT content was not induced with guanethidine in all regions and all days examined. These results suggest that guanethidine, crossing the blood-brain barrier at the neonatal stage, induced the degeneration of the nerve terminals and "collateral accumulation" of catecholamines in the central NE and DA neurons.