Effects of paraquat on the substantia nigra of the wistar rats: neurochemical, histological, and behavioral studies

Toxicol Appl Pharmacol. 1996 Mar;137(1):34-41. doi: 10.1006/taap.1996.0054.


Effects of paraquat on the substantia nigra of the male Wistar rats we re studied pharmacologically by a intracerebral injection of paraquat. The neurochemical, morphological, and behavioral changes observed after a unilateral intranigral injection of paraquat (1-5 microgram) were as follows: (1) neurochemically, paraquat caused dose-dependent depletion of dopamine in the ipsilateral striatum starting 2 weeks after treatment; this effect was long-lasting and irreversible. The ipsilateral striatal dopamine level in animals treated with 3 microgram paraquat was even decreased by 91.5%. (2) Morphologically, 2 microgram of paraquat produced marked loss of Nissl substances and prominent glial reaction in the substantia nigra, while 3 microgram of paraquat caused a severe loss of neurons. (3) Behaviorally, paraquat caused a vigorous rotational behavior in rats contralateral to the lesioned side in response to apomorphine administration (0.5 mg/kg, sc). This effect was dose-dependent and lasted for the entire 16-week experimental period. Taken together, these data indicate that intranigrally injected paraquat may possess marked neurotoxicity and induce degeneration of the rat nigrostriatal dopaminergic system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apomorphine / pharmacology
  • Behavior, Animal / drug effects
  • Corpus Striatum / drug effects
  • Corpus Striatum / metabolism
  • Dopamine / metabolism
  • Dose-Response Relationship, Drug
  • Herbicides / administration & dosage
  • Herbicides / toxicity*
  • Injections, Intraventricular
  • Male
  • Nissl Bodies / pathology
  • Paraquat / administration & dosage
  • Paraquat / toxicity*
  • Rats
  • Rats, Wistar
  • Rotation
  • Stereotyped Behavior / drug effects
  • Substantia Nigra / drug effects*
  • Substantia Nigra / metabolism
  • Substantia Nigra / pathology


  • Herbicides
  • Apomorphine
  • Paraquat
  • Dopamine