title: GM1 ganglioside enhances regrowth of noradrenaline nerve terminals in rat cerebral cortex lesioned by the neurotoxin 6-hydroxydopamine.
abstract: The effect of exogenous GM1 ganglioside on selectively noradrenaline-denervated rat cerebral cortex was investigated by measuring the spatial distribution of endogenous noradrenaline levels and by fluorescence histochemical analysis. A local noradrenaline denervation was produced by intracortical infusion of the selective catecholamine neurotoxin 6-hydroxydopamine for 3 or 7 days. The neurotoxin infusion caused an almost complete noradrenaline denervation in a restricted area around the infusion point as reflected by an almost complete long-term disappearance of noradrenaline nerve terminals and reduction of noradrenaline levels. There was with time a slow recovery of the levels, most likely related to a spontaneous noradrenaline nerve terminal regeneration. Post-treatment for 1 week with GM1 had very small effects on the 6-hydroxydopamine-induced reduction of the noradrenaline levels, while pretreatment with GM1 for 3 days before the neurotoxin infusion and continuing the GM1 administration for another 7-14 days significantly enhanced noradrenaline recovery, as observed both bio- and histochemically. GM1 had no effect on the 6-hydroxydopamine-induced noradrenaline depletion acutely, indicating that GM1 does not interfere with the direct neurotoxic actions of 6-hydroxydopamine. The present results thus indicate that exogenous GM1 enhances regrowth of noradrenaline nerve terminals which may be due to a regrowth stimulatory effect (regeneration/collateral sprouting) and/or related to protective actions of GM1 against retrograde degeneration of noradrenaline axons following the neurotoxin-induced lesion.
mesh_terms: D000320:Adrenergic Fibers / Q000187:drug effects; D000818:Animals; D001927:Brain Diseases / Q000139:chemically induced / Q000188:drug therapy*; D002540:Cerebral Cortex / Q000187:drug effects; D005677:G(M1) Ganglioside / Q000494:pharmacology / Q000627:therapeutic use*; D005732:Gangliosides / Q000627:therapeutic use*; D006892:Hydroxydopamines / Q000037:antagonists & inhibitors*; D008297:Male; D009638:Norepinephrine / Q000502:physiology; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000187:drug effects
chemical_list: D005732:Gangliosides; D006892:Hydroxydopamines; D005677:G(M1) Ganglioside; D016627:Oxidopamine; D009638:Norepinephrine