Abstract
The effects of a fraction (T1) of Tityus serrulatus scorpion venom prepared by gel filtration on gastric emptying and small intestinal transit were investigated in male Wistar rats. Fasted animals were anesthetized with urethane, submitted to tracheal intubation and right jugular vein cannulation. Scorpion toxin (250 microg/kg) or saline was injected iv and 1 h later a bolus of saline (1.0 ml/100 g) labeled with 99m technetium-phytate (10 MBq) was administered by gavage. After 15 min, animals were sacrificed and the radioactivity remaining in the stomach was determined. Intestinal transit was evaluated by instillation of a technetium-labeled saline bolus (1.0 ml) through a cannula previously implanted in the duodenum. After 60 min, the progression of the marker throughout 7 consecutive gut segments was estimated by the geometric center method. Gastric retention of the liquid test meal in rats injected with scorpion toxin (median: 88%; range: 52-95%) was significantly higher (P<0.02) than in controls (54%; 21-76%), an effect which was not modified by gastric secretion blockade with ranitidine. The progression of the isotope marker throughout the small intestine was significantly slower (P<0.05) in rats treated with toxin (1.2; 1.0-2.5) than in control animals (2.3; 1.0-3.2). Inhibition of both gastric emptying and intestinal transit in rats injected with scorpion toxin suggests an increased resistance to aboral flow, which might be caused by abnormal neurotransmitter release or by the local effects of venom on smooth muscle cells.
Highlights
Envenomation with scorpion toxin may produce a range of clinical manifestations related to the gastrointestinal tract, including salivation, epigastric pain, vomiting and diarrhea [1]
We show that injection of a partially purified fraction from T. serrulatus venom in anesthetized rats is followed by a remarkable inhibition of gastric emptying and of small intestinal transit
The results of this study show that the injection of a purified scorpion toxin fraction in anesthetized rats is associated with marked inhibition of both gastric emptying and intestinal transit
Summary
Envenomation with scorpion toxin may produce a range of clinical manifestations related to the gastrointestinal tract, including salivation, epigastric pain, vomiting and diarrhea [1]. Studies on isolated rat ileum have shown that a purified fraction of Tityus serrulatus scorpion venom induces rhythmic variations in tone and spastic contractions [5]. It was shown that toxin-C from T. serrulatus induces a sustained slowing of gastric emptying in rats [6]. Despite the clinical and experimental evidence that tityustoxin may influence the gastrointestinal tract and produce striking motor effects, its influence on gastrointestinal transit has not been extensively investigated. We show that injection of a partially purified fraction from T. serrulatus venom in anesthetized rats is followed by a remarkable inhibition of gastric emptying and of small intestinal transit
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