GM1 increases the content and mRNA of NGF in the brain of aged rats

Aged (20-22 months old) and young (3 months old) Sprague-Dawley rats were treated with GM1 ganglioside, 30 mg/kg i.p. for 30 days, and the content of nerve growth factor (NGF) and the high-affinity tyrosine receptor kinase (Trk) examined. NGF, estimated by a two-site enzyme immunoassay, was found moderately decreased in the frontal cortex and hippocampus, but not in the striatum of aged animals compared with young animals. The NGF decrease was accompanied by a reduction of NGF mRNA, evaluated by northern blot. Trk protein, determined by western blot with a pan-Trk antibody, was not altered in any region studied in the aged brain. GM1 treatment partially restored NGF and NGF mRNA in frontal cortex and hippocampus in the aged brain, but treatment had no effect on Trk protein. GM1 did not modify any of the parameters investigated in young animals.