In summary, the generation of the SAMP8-p75exonIII−/− mice described in this work uncovered a direct regulation of cholesterol synthesis genes by the TrkA/p75 axis and may facilitate the study of the degeneration of the cholinergic neurons by cholesterol dysregulation, a phenomenon also observed in several neurodegenerative diseases. The gene discussed is NTRK1; the disease is neurodegenerative disease.