The Effects of the δ-Opioid Agonist SNC80 on Hind-Limb Motor Function and Neuronal Injury After Spinal Cord Ischemia in Rats

In Brief Recent investigation suggested neuroprotective efficacy of a δ-opioid agonist in the brain. We investigated the effects of intrathecal treatment with a δ-opioid agonist (SNC80) on spinal cord ischemia (SCI) in rats. SCI was induced with an intraaortic balloon catheter. The animals were randomly allocated to one of the following five groups: 1) SNC80 before 9 min of SCI (SNC-9; n = 12), 2) vehicle before 9 min of SCI (V-9; n = 12), 3) SNC80 before 11 min of SCI (SNC-11; n = 10), 4) vehicle before 11 min of SCI (V-11; n = 12), or 5) sham (n = 12). SNC80 (400 nmol) or vehicle was administered 15 min before SCI. Forty-eight hours after reperfusion, hind-limb motor function was assessed by using the Basso, Beattie, Bresnahan (BBB) scale (0 = paraplegia; 21 = normal) and histological assessment of the L4 and L5 spinal segments was performed. BBB scores in the SNC-9 group were higher compared with those in the V-9 group (P < 0.05), whereas there were no differences in BBB scores between the SNC-11 and V-11 groups. There were significantly more normal neurons in the SNC-9 and SNC-11 groups than in the V-9 and V-11 groups (P < 0.05). The results indicate that intrathecal treatment with the δ-opioid agonist SNC80 can attenuate hind-limb motor dysfunction and neuronal injury after SCI in rats. IMPLICATIONS: Although recent evidence suggested neuroprotective efficacy of a δ-opioid agonist in the brain, there have been no data regarding its efficacy in the spinal cord. The results in this study showed that the δ-opioid agonist SNC80 attenuated neuronal injury after spinal cord ischemia in rats. Toshinori Horiuchi, Masahiko Kawaguchi, Takanori Sakamoto, Naoko Kurita, Satoki Inoue, Mitsutoshi Nakamura, Noboru Konishi, and Hitoshi Furuya