Involvement of pertussis toxin sensitive G-proteins in conditioned fear-potentiated startle: possible involvement of the amygdala

Brain Res. 1992 Jul 3;584(1-2):141-8. doi: 10.1016/0006-8993(92)90887-f.

Abstract

The present study evaluated the effects of intraventricular or intracerebral administration of pertussis toxin on fear-potentiated startle (a measure of conditioned fear) and shock sensitization (a measure of unconditioned fear). In Experiment 1 all animals were unilaterally implanted with cannulae into the lateral ventricle 1 week prior to 2 days of fear conditioning (ten light-shock pairings on each of 2 days). Five days later, animals were infused with either 1 microgram pertussis toxin or saline and tested for fear-potentiated startle 24 h after infusion and tested for shock sensitization 26 or 50 h after infusion. Pertussis toxin blocked the ability of a light conditioned stimulus to facilitate startle but did not alter the ability of acute footshock to increase startle amplitude in the same animals. In Experiment 2 bilateral infusion of 1 microgram pertussis toxin into the basolateral nuclei of the amygdala, but not the interpositus nuclei of the cerebellum, also blocked fear-potentiated startle when animals were tested 6 h after infusion. These findings suggest a role for pertussis toxin sensitive G-proteins, perhaps within the amygdala, in the expression of conditioned but not unconditioned fear.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acoustic Stimulation
  • Amygdala / anatomy & histology
  • Amygdala / drug effects*
  • Animals
  • Cerebellar Nuclei
  • Conditioning, Psychological / drug effects*
  • Electroshock
  • Fear / drug effects*
  • GTP-Binding Proteins / physiology*
  • Injections
  • Injections, Intraventricular
  • Male
  • Pertussis Toxin*
  • Rats
  • Rats, Inbred Strains
  • Reflex, Startle / drug effects*
  • Virulence Factors, Bordetella / administration & dosage
  • Virulence Factors, Bordetella / pharmacology*

Substances

  • Virulence Factors, Bordetella
  • Pertussis Toxin
  • GTP-Binding Proteins