RT Journal Article SR Electronic T1 De novo aging-related megaloneurites: alteration of NADPH diaphorase positivity in the sacral spinal cord of the aged dog JF bioRxiv FD Cold Spring Harbor Laboratory SP 483990 DO 10.1101/483990 A1 Yinhua Li A1 Yunge Jia A1 Wei Hou A1 Zichun Wei A1 Xiaoxin Wen A1 Yu Tian A1 Weijin Zhang A1 Lu Bai A1 Anchen Guo A1 Guanghui Du A1 Huibing Tan YR 2019 UL http://biorxiv.org/content/early/2019/06/26/483990.abstract AB The aging-related changes of NADPH-diaphorase (NADPH-d) in the spinal cord were studied in aged dogs. At all levels of the spinal cord examined, NADPH-d activities were present in neurons and fibers in the superficial dorsal horn, dorsal commissure and in neurons around the central canal. In addition, the sympathetic autonomic nucleus in the thoracic and rostral lumbar segments exhibited prominent NADPH-d cellular staining whereas the sacral parasympathetic nucleus (SPN) in the sacral segments was not well stained. Interestingly, we found abundant NADPH-d positive enlarged-diameter fibers termed megaloneurite, which characteristically occurred in the aged sacral segments, distributed in the dorsal gray commissure (DGC), lateral collateral pathway (LCP) the lateral fasciculi and the central canal compared with the cervical, thoracic and lumbar segments. The dense, abnormal NADPH-d megaloneurites occurred in extending from dorsal entry zone through lamina I along with the lateral boundary of the dorsal horn to the region of the SPN. These fibers were prominent in the S1-S3 segments but not in adjacent segments L5-L7 and Cx1 or in thoracolumbar segments and cervical segments. Double staining with GFAP, NeuN, CGRP, MAP2 and Iba1, NADPH-d megaloneurite colocalized with vasoactive intestinal peptide. Presumably, the megaloneurites may represent, in part, visceral afferent projections to the SPN and/or DGC. The NADPH-d megaloneurites in the aged sacral spinal cord indicated some anomalous changes in the neurites, which might account for a disturbance in the aging pathway of the autonomic and sensory nerve in the pelvic visceral organs.