Effects of lesions and ganglioside GM1 treatment on striatal polyamine levels and nigral DA neurons. A role of putrescine in the neurotropic activity of gangliosides.

The effects of a partial hemitransection at the meso-diencephalic level, with or without chronic ganglioside GMI treatment, have been evaluated on striatal polyamine levels, 7, 14 and 21 days after lesion, as well as on the ability of the polyamine synthesis inhibitor alpha-difluoromethylornithine (alpha-DFMO) to modulate the protective effects of chronic ganglioside GMI treatment against retrograde degeneration of the nigral dopamine (DA) nerve cell bodies (14 day time interval). The striatal polyamine levels were measured by high pressure liquid chromatography after dansylation of the polyamines. The nigral DA nerve cells were studied by means of tyrosine hydroxylase (TH) immunocytochemistry using the indirect immunoperoxidase technique. Quantitation was performed by means of morphometrical evaluation of the TH immunoreactive area of the substantia nigra. Seven days after partial hemitransection there is a marked increase (above 350%) in striatal putrescine levels, which is not modulated by chronic GMI treatment. This marked increase could, to a large extent, be counteracted by simultaneous treatment with alpha-DFMO, which blocks mainly the synthesis of putrescine. Twenty-one days after lesion chronic GMI treatment could produce an increase in striatal putrescine levels on the intact side and also after this time-interval prevent the reduction of striatal spermine levels. It was also found that simultaneous treatment with alpha-DFMO prevents the development of the protective action of chronic ganglioside GMI treatment against retrograde degeneration of the nigral DA neurons.