Neonatal intraspinal 6-hydroxydopamine: depletion of norepinephrine but not dopamine.

Neonatal intraspinal 6-hydroxydopamine (6-OHDA), administered in two 10 microgram doses at 24 h intervals, severely depleted spinal norepinephrine (NE) for at least 200 days. This neurochemical lesions was accompanied by a functional loss of spinal NE neurotransmission, as measured by the absence of the post decapitation reflex. While these data contraindicated regeneration of spinal NE terminals, enhanced brainstem NE levels in these rats provided evidence for terminal arborization, possibly representing aborted regrowth of NE fibres into the cord. Neither 6-OHDA alone nor in combination with desmethylimipramine pretreatment depleted spinal cord dopamine of serotonin.