Apelin-13 Prevents the Delayed Neuropathy Induced by Tri-ortho-cresyl Phosphate Through Regulation the Autophagy Flux in Hens.

Organophosphate-induced delayed neuropathy (OPIDN) is pathologically characterized by the swollen axon containing aggregations of microtubules, neurofilaments, smooth endoplasmic reticulum and multivesicular vesicles. At present, the exact mechanism of OPIDN is unclear and the effective therapeutic methods is not available to counter this syndrome. Recent studies had shown that the autophagy was involved in OPIDN. The adipocytokine Apelin is a peptide, Apelin and its receptor are abundantly expressed in the nervous system. Recent researches illuminated that Apelin was neuroprotective factor and Apelin could regulate the autophagy in vivo and vitro model. So we investigated the effect of Apelin-13 on the OPIDN induced by Tri-ortho-cresyl phosphate (TOCP) in hens and explored the role of autophagy in Apelin-13 preventing OPIDN. Adult Roman hens were given a single dose of 750 mg/kg TOCP by gavage for 21 days to induce OPIDN, and neural dysfunction were detected, and the formation of autophagosomes in spinal cord neurons was observed by transmission electron microscopy, and the molecular markers of autophagy microtubule-associated protein light chain-3 (LC3) and the autophagy substrates p62/SQSTM1 were determined by Western blot analysis. The results demonstrated that the obvious neurological dysfunction such as hindlimb paralysis and paralysis of gait was present, the number of autophagosomes in the neurons of spinal cords was significantly increased, the level of LC3-II and p62 expressions and the ratio of LC3-II/LC3-I in spinal cords and sciatic nerve were significantly increased in the OPIDN model group compared with the control group. Compared with the OPIDN model group, the neurological dysfunction of tens was obviously reduced, the clinical signs scores was significantly decreased, the number of autophagosomes in the neurons of hen spinal cords was significantly decreased, the level of LC3-II and p62 expressions and the ratio of LC3-II/LC3-I in spinal cords and sciatic nerve were significantly decreased in Apelin-13 treatment group. Our results suggested that Apelin-13 prevented against the OPIDN induced by TOCP in hens, which the mechanism might be associated with regulation autophagy flux by Apelin-13.