Alterations in the cortical and peripheral somatosensory evoked activity of rats treated with 3-nitropropionic acid

In this study, the action of 3-nitropropionic acid (3-NP) on the parameters of the cortical and peripheral evoked potentials was investigated in rats in different administration schemes (20 mg/kg i.p. during recording or 24 h before, and 5x 15 mg/kg daily 28 days before recording) to elucidate some neurophysiological effects of the substance. Responses in the somatosensory cortex and in the tail nerve, evoked by peripheral electric stimulation, were recorded in acute preparation under urethane anaesthesia. Amplitude, latency, and duration of the responses were measured. In rats treated 28 days before recording, latency of the cortical response was significantly (and the duration slightly) increased by 3-NP. The frequency dependence of the tail nerve response was more pronounced than that of the cortical response. After acute administration of 3-NP, the amplitude of the somatosensory evoked potential decreased. With double stimuli, the ratio of the amplitudes of the two responses (relative fatigue) was treatment-dependent. The relative refractory period of the tail nerve was altered both by acute and subacute 3-NP treatment. These results may be relevant in 3-NP based disease models but it needs further studies to find possible connections between the known biochemical effects of 3-NP and the functional neurotoxical changes described. The mode of evoked response analysis used is, theoretically, applicable for other neurotoxic effects and can be the base of development of functional biomarkers.