Changes of pathologic feature and microtubulin associated protein 2 in nervous system of hens with organophosphate-induced delayed neuropathy induced by 2,4,6-trimethylbenzoyl phenylphosphonate

Abstract

To develop the organophosphate-induced delayed neuropathy (OPIDN) hen model with 2,4,6-trimethylbenzoyl phenylphosphonate (TOCP), and observe the change of pathology and investigate the alterations of microtubulin associated protein 2 (MAP2). 48 adult hens were randomly divided into four groups, including three experimental groups and control group (n = 12 each group). The hens in three experimental groups were treated with TOCP by gavage at single dosages of 250, 500 and 750 mg/kg respectively while the control hens received an equivalent volume of corn oil by gavage. All hens were sacrificed after 21 days of treatment. Half hens in each group were dissected for HE examination and myelin straining of brain, spinal cord and sciatic nerve while brains of another half hens were dissected for the determination of MAP2 by western blotting. The delayed neurotoxicity symptoms of hens both in 500 and 750 mg/kg groups were consistently observed. The pathological changes of brain, spinal cord and sciatic nerve in 500 and 750 mg/kg groups showed nerve cells difference necrosis, increased cytoplasm basophilia, microglia proliferation, mono-nuclear and lymphocyte infiltration, myelin sheath extensive up to part of them disaggregation deletion. Compared with the control group, at 500 and 750 mg/kg respectively the increase of MAP2 was 25% and 23% (P < 0.01 and P < 0.05). The histopathologic changes of OPIDN caused by TOCP have dose-response relationship. The changes of MAP2 in nervous system may contribute to the occurrence and development of TOCP induced delayed neurotoxicity.