Diisopropyl phosphorofluoridate (
DFP) is an organophosphorus
ester, which produces mild
ataxia in 7-14 days and severe
ataxia or
paralysis in about 20 days (OPIDN) in hens. Previous studies in this laboratory have shown enhanced temporal expression of neurofilament (NF) subunit mRNAs in the spinal cord (SC) of
DFP-treated hens. The main objective of this investigation was to study the effect of
DFP administration on NF subunit mRNAs expression, when OPIDN is protected or potentiated by pre-treatment or post-treatment, respectively, with
phenylmethylsulfonyl fluoride (PMSF). The hens were sacrificed 1, 5, 10, and 20 days after the last treatment. In contrast with enhanced
mRNA expression of NF subunits reported in OPIDN, there was no alteration in the expression of NF subunits in the SC of PMSF-protected hens that did not develop OPIDN. PMSF post-treatment of
DFP-treated hens, which enhanced delayed neurotoxicity produced by a low dose of
DFP, exhibited decrease in the
mRNA expression of NF subunits in SC at all time periods (1-20 days) of observation. The expression of NF subunits was also studied in the degeneration-resistant tissue cerebrum of treated hens. The results from protected hens suggested that temporal enhanced expression of NF subunit mRNAs in
DFP-treated hens might be contributing to the development of OPIDN in hens. By contrast, PMSF post-treatment seemed to potentiate OPIDN by a mechanism different from that followed by
DFP alone to produce OPIDN.