[Alterations of neurofilament proteins in sciatic nerve of hens induced the delayed neurotoxicity by methamidophos].

Objective: To investigate the dynamic alterations of neurofilament subunits (NF) in sciatic nerve of hens with organophosphorus ester induced the delayed neurotoxicity or neuropathy (OPIDN).

Methods: Hens with OPIDN were produced by giving 30 mg/kg methamidophos subcutaneously to the 10-month-old Roman hens daily for 15 days, and sacrificed after manifesting neurotoxic clinical signs on the 2nd, 10th, and 23rd day respectively. The sciatic nerves were dissected, homogenized and centrifuged. The levels of NF in supernatant and pellet of sciatic nerves were examined by Western blotting respectively at different time from 2 to 23 days.

Results: Integrated optional density (IOD) of high molecular weight neurofilament (NF-H) in sciatic nerve pellet of hens on the day 2, 10, 23 after appearance of OPIDN were 145,117 +/- 17,038, 55,917 +/- 17,333 and 45,038 +/- 6,662 respectively. As compared with the control group (78,875 +/- 22,569), the contents of NF-H in pellet were increased by 84% on day 2, and decreased by 29% and 43% on day 10 and 23 respectively. IOD of NF-H in supernatant of sciatic nerves were 4,709 +/- 1,739, 12,337 +/- 3,205 and 16,745 +/- 931, which were reduced significantly as compared with the control (44,083 +/- 6,895) at three different times. There was no significant difference in IOD of middle molecular weight neurofilament (NF-M) between control group (27,925 +/- 2,660) and on day 2 (31,493 +/- 4,625) in pellet. Those were 19,367 +/- 2,746 and 6,612 +/- 1,119 respectively on day 10 and day 23 in pellet of hen's sciatic nerve, which were much less than that in control. Little were detected in supernatant on day 10, and the IOD of NF-M were 3,196 +/- 269 and 5,206 +/- 1,292 on day 2 and day 23 respectively, which were lessened by 81% and 70% as compared with the control (17,243 +/- 3,232). In sciatic nerve pellet of hens, IOD of low molecular weight neurofilament (NF-L) on day 2 was 39,211 +/- 3,800, which was much higher than that in the control (28,749 +/- 9,319). There were no significant differences between IOD on day 10 (27,974 +/- 3,611), day 23 (21,507 +/- 2,286) and the control. There was no detection both on day 2 and 10 in supernatant of sciatic nerve, and IOD of NF-L were 5,962 +/- 1,929 on day 23, which were reduced significantly compared with the control (11,897 +/- 352).

Conclusion: The alterations of NF in sciatic nerve might contribute to the occurrence and development of OPIDN.