C-fos mRNA induction in the central and peripheral nervous systems of diisopropyl phosphorofluoridate (DFP)-treated hens.

A single dose of diisopropyl phosphorofluoridate (DFP), an organophosphorus ester, produces delayed neurotoxicity (OPIDN) in hen. DFP produces mild ataxia in hens in 7-14 days, which develops into severe ataxia or paralysis as the disease progresses. Since, OPIDN is associated with alteration in the expression of several proteins (e.g., Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) alpha-subunit, tau, tubulin, neurofilament (NF) protein, vimentin, GFAP) as well as their mRNAs (e.g., NF, CaM kinase II alpha-subunit), we determined the effect of a single dose of DFP on the expression of one of the best known immediate-early gene (IEG), c-fos. C-fos expression was measured by Northern hybridization in cerebrum, cerebellum, brainstem, midbrain, spinal cord, and the sciatic nerves of hens at 0.5 hr, 1 hr, 2 hr, 1 day, 5 days, 10 days, and 20 days after a single 1.7 mg/kg, sc. injection of DFP. All the tissues (cerebrum, 52%; cerebellum, 55%; brainstem, 49%; midbrain, 23%; spinal cord, 80%; sciatic nerve, 157%) showed significant increase in c-fos expression in 30 min and this elevated level persisted at least up to 2 hr. Expressions of beta-actin mRNA and 18S RNA were used as internal controls. The significant increase in c-fos expression in DFP-treated hens suggests that c-fos may be one of the IEGs involved in the development of OPIDN.