Involvement of nitric oxide-dependent pathways of dorsolateral periaqueductal gray in the effects of ethanol in rats submitted to the elevated plus-maze test

Behav Brain Res. 2004 Aug 31;153(2):341-9. doi: 10.1016/j.bbr.2003.12.010.

Abstract

Our previous study showed the microinjection of drugs that influence the nitric oxide (NO)-mediated neurotransmission in the hippocampus impacts upon the anxiolytic-like effect of ethanol. In this study, we examined whether NO-dependent pathways of the dorsolateral periaqueductal gray (dlPAG) participate in the anxiolytic effect of ethanol in rats submitted to the elevated plus-maze test. We evaluated the impact on ethanol effects of the nitric oxide synthase (NOS) inhibitor 7-nitroindazole, the soluble guanylate cyclase inhibitor 1H-(1,2,4)-oxodiazolo (4,3-a) quinoxalin-1-one (ODQ), the cyclic guanylate monophosphate (cGMP) analogue 8-bromo-cGMP and the NO donor sodium nitroprusside. The results showed that ODQ and 7-nitroindazole increased the percentage of open arm entries and of time spent on open arms in the elevated plus maze in rats injected with ethanol at 1.0g/kg, a dose that did not produce anxiolysis per se. Conversely, 8-bromo-cGMP and sodium nitroprusside blocked the increased exploration of open arms exhibited by rats treated with a higher dose of ethanol (1.2g/kg). Taken together, the results suggest that the inhibition of NO-dependent pathways of the dlPAG enhances the anxiolytic effect of ethanol, whereas the activation of these pathways results in an opposite effect.

MeSH terms

  • Animals
  • Arousal / drug effects*
  • Arousal / physiology
  • Dose-Response Relationship, Drug
  • Ethanol / pharmacology*
  • Exploratory Behavior / drug effects
  • Fear / drug effects*
  • Fear / physiology
  • Injections, Intraperitoneal
  • Male
  • Maze Learning / drug effects*
  • Maze Learning / physiology
  • Neural Pathways / drug effects
  • Neural Pathways / physiology
  • Nitric Oxide / physiology*
  • Orientation / drug effects
  • Orientation / physiology
  • Periaqueductal Gray / drug effects*
  • Periaqueductal Gray / physiology
  • Rats
  • Rats, Wistar
  • Reaction Time / drug effects
  • Reaction Time / physiology

Substances

  • Nitric Oxide
  • Ethanol