Neurotoxic Effects of 2,5-Hexanedione on Normal and Neurofilament-Deficient Quail

Abstract

The neurotoxic effects of 2,5-hexanedione (2,5-HD) were investigated using neurofilament (NF)-deficient (Quv) Japanese quail in comparison with normal Japanese quail. Both Quv and normal Japanese quail were inoculated intraperitoneally with 350 mg/kg/day 2,5-HD for 6 consecutive wk. The results of 2,5-HD exposure differed substantially between the 2 strains of Japanese quail. The 2,5-HD-exposed normal quail showed leg paralysis about 4 wk after initiation of dosing. Some treated normal quail fell into dysstasia and died of nutritional disturbances. Histologically, 2,5-HD-treated normal quail had NF-rich axonal swellings and degeneration in the distal parts of the peripheral nerves, spinal cord, and cerebellar peduncles. In contrast, 2,5-HD-injected Quv quail showed tonic convulsion, ataxia gait, severe quivering, and excitation about 2-3 days after administration. Some treated Quv birds died immediately after systemic tonic convulsion, probably because of asphyxia. Although all treated Quv quail showed neurologic signs, there were no recognizable 2,5-HD-induced lesions in the nervous system. After about 4-6 wk of dosing, 2,5-HD induced distal axonopathy in normal quail and acute neurotoxicity in Quv quail.