Chlordimeform produces profound, selective, and transient changes in visual evoked potentials of hooded rats.
Rat visual function was tested after acute exposure to chlordimeform (CDM), a formamidine insecticide/acaricide. Adult male Long-Evans rats were surgically implanted with epidural recording electrodes overlying visual cortex and tested 1 week later. Pattern reversal-evoked potentials (PREPs), flash-evoked potentials (FEPs), and FEP recovery ratios were measured after acute CDM administration. Averaged recordings obtained during 200 reversals of a black-and-white square wave grating comprised the PREPs, and those obtained during 128 paired strobe lamp flashes comprised the FEPs. In the first study, which examined dose-response relationships, i.p. injections of 0 (saline), 5, 15, or 40 mg/kg CDM-HCl were administered 30 min prior to testing. The PREP amplitudes showed large dose-related changes in the CDM-treated rats. PREP N1P1 and P1N3 peak-to-peak amplitudes increased more than 200% in the 40 mg/kg group. In contrast, FEP amplitudes and FEP recovery ratios were unchanged by CDM. Both PREP and FEP peak latencies were increased by CDM in dose-related fashions. In the second study, which examined the time course of CDM action, PREPs and paired-pulse FEPs were recorded 3, 6, and 24 h after dosage with either 0 or 40 mg/kg CDM. All evoked potential changes were large at 3 and 6 h, but had returned to control values by 24 h. In summary, acute exposure to CDM temporarily increased both the amplitude and latency of PREPs, but only the latency of FEPs.
D000578:Amidines / Q000494:pharmacology*; D000818:Animals; D002742:Chlorphenamidine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005074:Evoked Potentials, Visual / Q000187:drug effects*; D007700:Kinetics; D008297:Male; D051381:Rats; D014793:Visual Cortex / Q000502:physiology
D000578:Amidines; D002742:Chlorphenamidine