A biochemical and morphological study of the altered growth pattern of central catecholamine neurons following 6-hydroxydopamine.

In this study the effect of administering 6-hydroxydopamine (6-OHDA) intracisternally on brain catecholamine content and fluorescence patterns of cerebellar processes was examined. It was found that intracisternal injection of 6-OHDA resulted in widely diverging effects depending upon the dose of 6-OHDA, age of the animal upon injection and the length of the post injection interval. Small doses of 6-OHDA (3 and 10 microgram) selectively depleted telencephalic and upper brain stem NE while larger doses of 6-OHDA (30 and 100 microgram) infringed on dopaminergic as well as noradrenergic neurons. In addition, the lower doses of 6-OHDA, but not the higher ones, led to an approximately two-fold accumulation of NE in the lower brain stem and cerebellum. Morphological observations suggested that the cerebellar norepinephrine accumulation after 10 microgram 6-OHDA was attributable primarily to an invasion of noradrenergic processes into the cerebellum.