Application of precolumn oxidation HPLC method with fluorescence detection to evaluate saxitoxin levels in discrete brain regions of rats

Saxitoxin (STX) is one of several related toxins that cause paralytic shellfish poisoning (PSP). This toxin blocks neuronal transmission by binding to the voltage-gated Na+ channel and for this reason, it has been widely used in the study of Na+ channel. The aim of this study was to analyze STX distribution in different rat brain regions after its acute intraperitoneal (i.p.) administration. Male rats (150–200 g) were injected i.p. with STX (5 and 10 μg/kg of body weight). After three time intervals of 30, 60, and 120 min (for 5 μg/kg STX dose) and 30 min (for 10 μg/kg STX dose) animals were sacrificed by cervical dislocation. Brains were removed and dissected in seven regions. STX concentration was measured using a precolumn oxidation high-performance liquid chromatographic method with fluorescence detection (HPLC/FLD). STX was found in all the regions evaluated at ppm levels meaning that STX peripherical administered across the blood–brain barrier and is distributed along the whole brain.