Effect of ACTH4-10Pro8-Gly9-Pro10 on anti-inflammatory cytokine (IL-4, IL-10, IL-13) expression in acute spinal cord injury models (male Sprague Dawley rats)

Abstract

Background: Spinal cord injury (SCI) is a damage to the spinal cord caused mainly by trauma resulting in major motor, sensory and autonomic dysfunctions. Its final neurological outcome is determined by both primary and secondary injury processes. A key component of secondary injury mechanisms after initial trauma is neuroinflammation. A neuroprotective compound, ACTH4-10Pro8-Gly9-Pro10 (ACTH4-10) also known as semax, has shown neuroprotective and anti-inflammatory properties. ACTH4-10 has also been actively used in the treatment of brain ischemia without serious complication reported. Here, we analyzed the effects of ACTH4-10 at regulating the inflammatory cascade in SCI by looking at anti-inflammatory cytokine (IL-4, IL-10 and IL-13) levels after acute SCI. Method: We carried out laminectomies in male Sprague Dawley rats at the second thoracic vertebrae. After laminectomy, we exposed the myelum and created mild SCI models with 20-g, and severe SCI with 35-g aneurysm clips. ACTH4-10 was administered intranasally to the treatment group and 0.9% NaCl to the control group (placebo). Both groups were kept alive and terminated at 3 and 6 hours. The tissue sample preparations were fixed in formalin and examined for immunohistochemistry. Quantitative measurement of the cytokines was done in the posterior horn area with specific associated anti-monoclonal antibodies. Results: Rats with mild SCI that were given ACTH4-10 showed greater anti-inflammatory levels at 3 hours post-compression but only IL-10 and IL-13 were elevated significantly at 6 hours. Rats with severe compression in ACTH4-10 group showed greater levels of IL-10, IL-13 at 3 hours and IL-4, IL-10 at 6 hours compared with the placebo group. Conclusions: Administration of ACTH4-10Pro8-Gly9-Pro10 intranasal can increase anti-inflammatory cytokine expression in Sprague Dawley rat models with mild and severe SCI. Expression of anti-inflammatory cytokines was greater in mild compression and 3-hour termination. Further research is needed to determine the optimal dose and clinical outcome in vivo.