Regulation of Zinc Transporter 1 Expression in Dorsal Horn of Spinal Cord After Acute Spinal Cord Injury of Rats by Dietary Zinc

Zinc concentrations in the dorsal horn of spinal cord are important for wound healing, neurological function, and reproduction. However, the response of the spinal cord to alterations in dietary zinc is unknown in rats after spinal cord injury (SCI). The current study explored cellular zinc levels and zinc transporter 1 (ZnT1) expression in the dorsal horn of spinal cord with different dietary zinc after SCI. A hundred and forty-four male Wistar rats were randomly divided into four groups: sham-operated group (30 mg Zn/kg), zinc-high dietary SCI model group (ZH, 180 mg Zn/kg), zinc-adequate dietary SCI model group (30 mg Zn/kg), and marginal zinc-deficient dietary SCI model group (MZD, 5 mg Zn/kg). To test the hypothesis that dietary zinc may regulate role of ZnT1 expression in dorsal horn after acute SCI, we traced ZnT1 proteins and zinc ions with immunohistochemistry, western blot, and autometallography. Zinc and ZnT1 levels of the dorsal horn in ZH significantly increased after surgery (P < 0.05), reached peak level (P < 0.05) on the seventh day, and subsequently levels of their expression began to decrease. But zinc levels and ZnT1 expression of spinal cord in MZD dietary groups decreased (P < 0.05) in SCI. There was a positive correlation between ZnT1 protein and zinc content in spinal cord (R = 0.49880, P = 0.0492). We found that both zinc and ZnT1 expressions in spinal cord are regulated by dietary zinc. These results indicate that dietary zinc may regulate the expression of ZnT1 in the dorsal horn of spinal cord after SCI. ZnT1 may, at the same time, play a significant role in the maintenance of zinc homeostasis in SCI.