Developmental localization of noradrenergic innervation to the rat cerebellum following neonatal 6-hydroxydopa and morphine treatment.
In order to demonstrate the influence of morphine on the developmental localization of regenerated noradrenergic fibers in rat cerebellum, a glyoxylic histofluorescent method and radiometric assay for norepinephrine (NE) were utilized. An initial reduction of NE in the cerebellum after 6-hydroxydopa [6-OHDOPA; 60 micrograms/g intraperitoneally (i.p.)] was followed by a return to control levels at 3 days, and an elevation above control levels at 7 days. The initial rates of recovery of NE in the cerebellum of the 6-OHDOPA group of rats and the group receiving morphine (20 micrograms/g i.p.) in combination with 6-OHDOPA were identical up to 7 days. However, by 14 days NE content was further elevated in the cerebellum of the morphine +6-OHDOPA group. Histofluorescent microscopic observations of the cerebellar cortex correlated with the biochemical findings. A reduction in cerebellar NE content at 3 days was associated with a reduction in the number of visible histofluorescent fibers in the cerebellar cortex. By 7 days the relative number of fibers in the 6-OHDOPA groups was similar to that seen in the control group, but by 9 days the relative number of fluorescent fibers in the cerebellar cortex was increased above control. By 13 days there was a further increase in the relative number of fluorescent fibers in the cerebellar cortex of the morphine +6-OHDOPA group, as compared to the group treated with 6-OHDOPA alone. These findings provide an anatomic correlate for recovery of noradrenergic fibers after 6-OHDOPA, and demonstrate an action of morphine in enhancing regenerative sprouting.
D000375:Aging; D000818:Animals; D002525:Cerebellar Cortex / Q000187:drug effects; D002531:Cerebellum / Q000187:drug effects*; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D009020:Morphine / Q000494:pharmacology*; D009412:Nerve Fibers / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
C001388:6-hydroxydopa; D004295:Dihydroxyphenylalanine; D009020:Morphine; D009638:Norepinephrine