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Anxiogenic activity of centrally administered scorpion (Mesobuthus tamulus) venom in rats
1Department of Pharmacology, Banaras Hindu University, Varanasi, India.
Abstract:
The anxiogenic action of intracerebroventricularly (i.c.v.) administered Mesobuthus tamulus venom (MTV) was investigated in rats. MTV (1, 3 and 5 g/rat, i.c.v.) induced a dose-related anxiogenic response which was qualitatively comparable to that produced by yohimbine (2 mg/kp, i.p.), an established anxiogenic agent. Both MTV and yohimbine reduced exploratory activity and rears, while increasing immobility and defaecation, in the open-field test. Likewise, both the drugs decreased the number of entries and time spent on the open arms of the elevated plus-maze, reduced social interaction and increased feed-latency in a novel environment. Rat brain levels of tribulin, a postulated endocoid indicator of anxiety, assessed in terms of endogenous monoamine oxidase (MAO) A and B inhibitor activity, were increased by both MTV and yohimbine. The results indicate that the venom has significant anxiogenic activity, which is consonant with some of the clinical symptoms seen after scorpion sting.
Insights
Mesobuthus tamulus venom (MTV) causes anxiety in rats, similar to yohimbine. This venom increases anxiety indicators and tribulin levels, explaining symptoms seen after scorpion stings.
Area of Science:
- Neuroscience
- Toxicology
- Pharmacology
Background:
- Scorpion stings can cause anxiety-like symptoms in humans.
- The neurotoxic effects of Mesobuthus tamulus venom (MTV) are not fully understood.
- Anxiety is a complex emotional state influenced by neurochemical factors.
Purpose of the Study:
- To investigate the anxiogenic (anxiety-inducing) effects of Mesobuthus tamulus venom in a rat model.
- To compare the anxiogenic effects of MTV with a known anxiogenic agent, yohimbine.
- To explore the potential neurochemical mechanisms underlying MTV-induced anxiety.
Main Methods:
- Administration of varying doses of MTV intracerebroventricularly (i.c.v.) in rats.
- Behavioral testing using the open-field test and elevated plus-maze.
- Assessment of tribulin levels in rat brains, measured by monoamine oxidase (MAO) A and B inhibitor activity.
Main Results:
- MTV induced a dose-related anxiogenic response in rats, comparable to yohimbine.
- Both MTV and yohimbine reduced exploratory behaviors and increased anxiety indicators like immobility and defecation.
- MTV and yohimbine increased rat brain tribulin levels, suggesting a role in anxiety.
Conclusions:
- Mesobuthus tamulus venom exhibits significant anxiogenic activity.
- The venom's effects are mediated, at least in part, by mechanisms involving tribulin and MAO inhibition.
- These findings provide a potential explanation for the anxiety symptoms observed in human scorpion sting victims.