Neurotoxic effects of acute and subacute formaldehyde exposures in mice

In this study, the effects of acute and subacute formaldehyde (FA) exposures on spontaneous locomotor activity (SLMA), wet dog shake (WDS) behavior and pentylenetetrazole (PTZ) induced seizures were evaluated in Balb/C mice. SLMA was concentration dependently reduced after acute FA exposures at 1.8, 3.2, 4.5, 6.4, 9.7, and 14.8 ppm. The incidence of WDS behavior was increased only after acute FA exposures at 1.8, 3.2 and 6.4-ppm. PTZ-injections caused more intensive seizures in mice acutely exposed to FA only at 1.8 ppm. Meanwhile, the incidence of PTZ induced seizures was significantly lower after acute FA exposure at 14.8 ppm. SLMA was also reduced after subacute FA exposure at 2.0 ppm for 3 weeks. The inhibitory effects were significant after 1-week exposure at this concentration, but a tolerance developed at the end of the second week. As the concentration increased to 3.2 ppm, SLMA has found to be reduced after 2-week exposure. There was no change either on the incidence of WDS or on the parameters of PTZ-induced seizures, due to the subacute exposures of FA at the respective concentrations. In conclusion, based upon these data, acute and subacute exposures of FA produce a significant behavioral depression on mice. The data also suggest that acute FA exposures at low concentrations (such as 1.8 ppm) may increase the excitability of central nervous system (CNS).