Spinal and Supraspinal Changes in Vitamin D3 Up-regulated Protein 1 (VDUP1) Gene Expression after Spinal Cord Injury

Background: Vitamin up-regulated protein 1 (VDUP1) gene is known to be a novel member of the early response genes and an oxidative stress mediator. This study was designed to elucidate VDUP1 expression and its involvement in central sensitization after spinal cord injury (SCI). Methods: Contusion injury was produced at spinal segment T10 (20 mm drop, 10 g rod) in adult male Sprague-Dawley rats (250-300 g). Withdrawal responses were measured using von Frey filaments and acetone on the 1st, 3rd and 7th days after SCI. The expressions of VDUP1 gene in the brain and in the cervical and lumbar spine were examined by immunohistochemistry on the 1st, 3rd and 7th day after SCI. Results: VDUP1 gene was detected in a few oligodendrocytes in the spinal cord and in the brain of control rats. VDUP1 gene expression increased in most of the neurons and ependymal cells in the central canal of the injured (lumbar) spinal cord 1 day after SCI. This expression gradually decreased in majority of cells from day 1 to day 7 after SCI. VDUP1 gene expression was also observed to be increased 1 day after SCI, and gradually to decrease from 1 day to 7 days after SCI. The neurons in the intact (cervical) spinal cord VDUP1 gene expression increases maximally 3 days after SCI in the cerebral cortex and the thalamus. Neuropathic pain behavior was triggered by the plantar surface of the fore foot after SCI. Conclusions: These results show that the VDUP1 gene may be an early modulator of transneuronal stress response after SCI, and to be related to the central sensitization of neuropathic pain behavior after SCI.