Effects of Systemic Administration of Saxitoxin on Serotonin Levels in Some Discrete Rat Brain Regions

The present study is related with the toxicity of Saxitoxin (STX), a neurotoxic compound, produced by certain dinoflagellates. Its main toxicological activity is observed through the blockage of the sodium channels. It might originate a reduction of the amplitude and speed of conduction of the action potentials by the peripheral and central nerves, as well as weakening of the skeletal muscular contraction. The aim of this study was to analyze the effect of STX on serotonin (5-HT) levels in some discrete rat brain regions after acute intraperitoneal (i.p.) administration of 5 and 10 mu g Kg(-1) STX body weight. 5-HT levels were analyzed at 30, 60 and 120 min after the administration of 5 mu g Kg(-1) of STX, and 30 min after administration of 10 mu g K-1 of the toxin. Animals were sacrificed by cervical dislocation and the brains were removed and dissected in seven regions. Tissue samples were analyzed by using a chromatographic technique with electrochemical detection (HPLC/ED). Our results suggest that systemic administration of the STX reaches the brain producing alterations in neurotransmission increasing the levels of 5-HT in all the brain regions studied. With respect to the serotonin metabolite, 5-hidroxiindoleacetic acid (5-HIAA), we observed an increase in its levels in all the brain regions studied with the high dose of toxin, whereas different alterations were observed with the low dose of toxin.