Effects of GM1 ganglioside on developing and mature serotonin and noradrenaline neurons lesioned by selective neurotoxins

The effect of exogenous GM1 ganglioside on selective neurotoxin-induced lesions of serotonin (5-HT) and noradrenaline (NA) neurons in both the central and peripheral nervous systems has been investigated in developing and adult rats and mice by employing neuro- and histochemical techniques. 5,7-Dihydroxytryptamine (5,7-HT) was used to lesion 5-HT neurons, and 6-hydroxydopamine (6-OH-DA) was used to lesion NA neurons. In most lesion models investigated the neurotoxin causes primarily an axonal nerve terminal damage without notably affecting the perikarya. There was no evidence indicating that GM1 interferes with the primary and direct neurodegenerative actions of 5,7-HT or 6-OH-DA on 5-HT and NA nerve terminals, respectively. In all lesion models GM1 had in the chronic stage a counteracting effect on the neurotoxin-induced nerve terminal lesion or enhanced regrowth. The present results are compatible with the view that GM1 has a regrowth-stimulating effect and/or protective actions against secondary retrograde degeneration following the initial nerve terminal lesion induced by the neurotoxin.