Short-term neuronal effects of fumonisin B1 on neuronal activity in rodents

[Display omitted] •Acute effects of the mycotoxin FB1 on neuronal activity were investigated•FB1 was applied directly on cultures and slices or administered in vivo•Electrophysiological and immunohistochemical measurements were carried out•FB1 increased the excitability of neurons and neuronal networks treated directly•FB1 had no effects on neocortical or hippocampal activity in vivo Fumonisin B1 (FB1) is a mycotoxin produced by microscopic fungi (mostly Fusarium species), which may infect our major crops. The toxin inhibits the development of these plants and may also have harmful effects on animals and humans consuming the infected crops. FB1 inhibits sphingolipid biosynthesis which leads to altered membrane characteristics and consequently, altered cellular functions. There are some indications that the toxin has inhibitory effects on neuronal activity in case of repeated consumption, presumably due to sphingolipid depletion. However, according to new literature data, FB1 may have acute excitatory neural effects, too, via different mechanisms of action. Therefore, in the present study, we addressed the neuronal network effects of FB1 following acute treatment, using different electrophysiological techniques in vitro and in vivo. Acute treatments with FB1 (10–100 μM) were carried out on brain slices, tissue cultures and live animals. After direct treatment of samples, electrically evoked or spontaneous field potentials were examined in the hippocampus and the neocortex of rat brain slices and in hippocampal cell cultures. In the hippocampus, a short-term increase in the excitability of neuronal networks and individual cells was observed in response to FB1 treatment. In some cases, the initially enhanced excitation was reversed presumably due to overactivation of neuronal networks. Normal spontaneous activity was found to be stimulated in hippocampal cell cultures. Seizure susceptibility was not affected in the neocortex of brain slices. For the verification of the results caused by direct treatment, effects of systemic administration of FB1 (7.5 mg/kg, i.p.) were also examined. Evoked field potentials recorded in vivo from the somatosensory cortex and cell activation measured by the c-fos technique in hippocampus and somatosensory cortex were analyzed. However, the hippocampal and cortical stimulatory effect detected in vitro could not be demonstrated by these in vivo assays. Altogether, the toxin enhanced the basic excitability of neurons and neuronal n