In vitro neuropharmacological evaluation of penitrem-induced tremorgenic syndromes: importance of the GABAergic system.

The effects of the fungal neurotoxin penitrem A on the GABAergic and glutamatergic systems in rat brain were evaluated. Penitrem A inhibited binding of the GABA(A)-receptor ligand [³H]TBOB to rat forebrain and cerebellar membrane preparations with IC50 (half maximal inhibitory concentration) values of 11 and 9 µM, respectively. Furthermore, penitrem A caused a concentration-dependent increase of [³H]flunitrazepam and [³H]muscimol binding in rat forebrain, but not in cerebellar preparations. The stimulation of [³H]flunitrazepam binding by penitrem A was abolished by the addition of GABA. In cerebellar preparations, a different pharmacological profile was found, with penitrem A allosterically inhibiting [³H]TBOB binding by interacting with a bicuculline-sensitive site. Moreover, penitrem A inhibited the high affinity uptake of GABA and glutamate into cerebellar synaptosomes with IC50 values of 20 and 47 µM, respectively. The toxin showed no effect on NMDA or AMPA glutamate receptor binding. In conclusion, our results suggest that penitrem A exerts region-specific effects in the brain, leading to positive modulation of GABA(A)-receptor function in forebrain. Conversely, penitrem A may act as a bicuculline-like convulsant in cerebellum.

Determination of cyclopiazonic acid in food and feeds by liquid chromatography-tandem mass spectrometry.

A new, fast and efficient multiple reaction monitoring (MRM) high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of cyclopiazonic acid (CPA) in mixed feed, wheat, peanuts and rice is presented. The analytical methodology involves sample extraction with an alkaline methanol-water mixture, defatting with hexane and quantification using HPLC-MS/MS without further treatment of sample extracts. Reversed-phase liquid chromatography using a C18 stationary phase coupled to negative mode electrospray triple quadrupole tandem mass spectrometry was applied. The limit of detection was 5 microg/kg while the limit of quantification was 20 microg/kg in the matrices investigated. The detector response was found to be linear over the range 25-250 microg/kg in feed and 25-500 microg/kg in wheat, peanuts and rice. The mean overall recoveries (n=18) of CPA varied from 79% to 114% in the range of concentrations studied over a period of 4 months. Mean recoveries (n=3 or 6) of CPA in wheat, peanuts and rice varied from 70% to 111%, 77% to 116% and 69% to 92%, respectively. The method was successfully applied to the analysis of feed and rice samples artificially infected with the fungal strain Penicillium commune, where the toxin was found at different levels.