Long-term protective effects of human recombinant nerve growth factor and monosialoganglioside GM1 treatment on primate nucleus basalis cholinergic neurons after neocortical infarction

Infarction induces biochemical and morphological retrograde degenerative changes in cholinergic neurons of the rat nucleus basalis magnocellularis [Sofroniew et al. (1983) Brain Res. 289, 370-374]. In the present study, this lesion model has been reproduced in the non-human primate (Cercopithecus aethiops) to investigate whether degenerative changes affecting the cortex surrounding the lesioned area and the ipsilateral basal forebrain are prevented by the early administration of recombinant human nerve growth factor alone or in combination with the monosialoganglioside GM1. Six months after surgery and treatment, the monkeys were processed either for biochemistry (choline acetyltransferase assay) or immunocytochemistry. In lesioned vehicle-treated animals, choline acetyltransferase activity significantly decreased by 28% in the cortex surrounding the injured area and by 31% in the ipsilateral nucleus basalis of Meynert when compared with values of sham-operated monkeys. These biochemical changes were fully prevented with the administration of nerve growth factor alone or in combination with the monosialoganglioside GM1. The morphometrical analysis revealed a significant shrinkage of cholinergic neurons (61 ± 1.4% of sham-operated cell size) and loss of neuritic processes (59 ± 10% of sham-operated values) within the intermediate nucleus basalis region of lesioned vehicle-treated animals. Although a protection of the cholinergic cell bodies within the nucleus basalis was found with both treatments, a significant recovery of the neuritic processes (84 ± 7.2% of sham-operated values) was assessed only in the double-treated monkeys. These results indicate that the early administration of nerve growth factor alone or in combination with the monosialoganglioside GM1 induces a long-term protective effect on the nucleus basalis cholinergic neurons in cortical injured non-human primates.