Therefore, this study aims to search the potential evidences of non-MN in the pathogenesis of ALS via exploring potential relationships between 5-hydroxytryptamine (5-HT) neurons and the development of ALS.<h4>Methods</h4>We employed fluorescent immunohistochemistry to investigate the altered distribution patterns of 5-HT and tryptophan hydroxylase 2 in the spinal cord and brainstem of Tg(SOD1*G93A)1Gur (TG) and wild-type (WT) mice. The gene discussed is TPH2; the disease is amyotrophic lateral sclerosis.