Pharmacological characterization of the presynaptic activity of Tityus serrulatus venom in the rat anococcygeus muscle

Cleber E. Teixeira, Fernanda Priviero, Cristina E. Okuyama, Gilberto De Nucci, Edson Antunes

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Scorpion venoms are known to cause peripheral nerve stimulation with enhanced autonomic responses. This study, therefore, examined the effects of Tityus serrulatus venom (TSV) on adrenergic, cholinergic and nitrergic nerve fibers using the rat anococcygeus muscle. The contractile effects of TSV (1 μg/ml) and electrical field stimulation were markedly reduced by phentolamine (5 μM), prazosin (0.1 μM), guanethidine (30 μM) and tetrodotoxin (TTX, 1 μM), whereas imipramine (3 μM) enhanced these responses. The responses to tyramine (10 μM) were partially reduced by guanethidine and completely blocked by phentolamine, prazosin and imipramine. Atropine (1 μM) fully prevented carbachol (CCh, 30 μM)-induced contractions without affecting those mediated by TSV. Neostigmine significantly potentiated TSV-and ACh-evoked contractions, whereas hexamethonium had no effect. The relaxant responses induced by EFS and TSV (3 μg/ml) were completely blocked by L-NAME (100 μM), ODQ (1 μM) or TTX (1 μM). Addition of L-arginine (1 mM) reversed the effect of L-NAME. Thus, the motor and inhibitory responses of TSV in the rat anococcygeus muscle are mediated by prejunctional mechanisms dependent on Na+ channel activation, causing the stimulation of NA and NO release from adrenergic and nitrergic nerve fibers, respectively.

Original languageEnglish (US)
Pages (from-to)451-460
Number of pages10
JournalToxicon
Volume42
Issue number5
DOIs
StatePublished - Oct 1 2003
Externally publishedYes

Fingerprint

Venoms
Muscle
Rats
Pharmacology
Muscles
Nitrergic Neurons
Guanethidine
Imipramine
Prazosin
Phentolamine
NG-Nitroarginine Methyl Ester
Nerve Fibers
Adrenergic Agents
Scorpion Venoms
Neostigmine
Hexamethonium
Tyramine
Fibers
Tetrodotoxin
Carbachol

Keywords

  • ACh, acetylcholine
  • Adrenergic transmission
  • Anococcygeus muscle
  • CCh, carbachol
  • EFS, electrical field stimulation
  • GTN, glyceryl trinitrate
  • Na channels
  • Nitrergic transmission
  • Nitric oxide
  • Noradrenaline
  • Tityus serrulatus

ASJC Scopus subject areas

  • Toxicology

Cite this

Pharmacological characterization of the presynaptic activity of Tityus serrulatus venom in the rat anococcygeus muscle. / Teixeira, Cleber E.; Priviero, Fernanda; Okuyama, Cristina E.; De Nucci, Gilberto; Antunes, Edson.

In: Toxicon, Vol. 42, No. 5, 01.10.2003, p. 451-460.

Research output: Contribution to journalArticle

Teixeira, Cleber E. ; Priviero, Fernanda ; Okuyama, Cristina E. ; De Nucci, Gilberto ; Antunes, Edson. / Pharmacological characterization of the presynaptic activity of Tityus serrulatus venom in the rat anococcygeus muscle. In: Toxicon. 2003 ; Vol. 42, No. 5. pp. 451-460.
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AU - De Nucci, Gilberto

AU - Antunes, Edson

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AB - Scorpion venoms are known to cause peripheral nerve stimulation with enhanced autonomic responses. This study, therefore, examined the effects of Tityus serrulatus venom (TSV) on adrenergic, cholinergic and nitrergic nerve fibers using the rat anococcygeus muscle. The contractile effects of TSV (1 μg/ml) and electrical field stimulation were markedly reduced by phentolamine (5 μM), prazosin (0.1 μM), guanethidine (30 μM) and tetrodotoxin (TTX, 1 μM), whereas imipramine (3 μM) enhanced these responses. The responses to tyramine (10 μM) were partially reduced by guanethidine and completely blocked by phentolamine, prazosin and imipramine. Atropine (1 μM) fully prevented carbachol (CCh, 30 μM)-induced contractions without affecting those mediated by TSV. Neostigmine significantly potentiated TSV-and ACh-evoked contractions, whereas hexamethonium had no effect. The relaxant responses induced by EFS and TSV (3 μg/ml) were completely blocked by L-NAME (100 μM), ODQ (1 μM) or TTX (1 μM). Addition of L-arginine (1 mM) reversed the effect of L-NAME. Thus, the motor and inhibitory responses of TSV in the rat anococcygeus muscle are mediated by prejunctional mechanisms dependent on Na+ channel activation, causing the stimulation of NA and NO release from adrenergic and nitrergic nerve fibers, respectively.

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