Megaloneurite, a giant neurite of vasoactive intestinal peptide and nitric oxide synthase in the aged dog and identification by human sacral spinal cord

Megaloneurite of NADPH diaphorase (NADPH-d) positivity is a new kind of aging-related neurodegeneration and also co-localized with vasoactive intestinal peptide (VIP) in the sacral spinal cord of aged dog and monkey. However, no immunocytochemistry of VIP was exclusively tested in the aged dog and no evidence has been reported in the aged human spinal cord. Aged dogs were used to examine the distribution of VIP immunopositivity in the sacral spinal cord. Immunocytochemistry of VIP and alpha-synuclein were also examined in the aged human spinal cord. The VIP immunopositivity in aged dog was reconfirmed our previous finding illustrated by immunofluorescent study. Megalogneurite was also identified by nitric oxide synthase (NOS) immunoreaction in aged dog. The VIP positive megaloneurites both in age dog and human were detected in dorsal root entry zoon, Lissauer’s tract, dorsal commissural nucleus and anterior commissural gray as well as in the lateral funiculus of the sacral spinal cord exclusive of other segments of spinal cord. Alpha-synuclein positivity was present mini-aggregation and Lewy body in the sacral spinal cord of aged human, that also occurred in the lumber, thoracic and cervical spinal cord. It was firstly tested that VIP megaloneurites occurred in the aged human sacral spinal cord, especially in the white matter. Megaloneurites identified by NADPH-d-VIP-NOS immunoreaction could implicate for the dysfunction of pelvic organs in the aged human being.