Activation of periaqueductal grey pools of beta-endorphin by analgetic electrical stimulation in freely moving rats

Brain Res. 1987 Mar 24;407(1):199-203. doi: 10.1016/0006-8993(87)91239-x.


Electrical stimulation of the ventral midbrain periaqueductal grey (PAG) elicited an antinociception (analgesia) in freely moving rats. Stimulated animals displayed a pronounced decrease in levels of immunoreactive (ir)-beta-endorphin (beta-EP) in the midbrain PAG. This depletion was selective in that: animals placed in the chamber and not stimulated revealed neither an analgesia nor an alteration in levels of ir-beta-EP. No change in levels of ir-beta-EP was detectable in other brain regions. Both stimulated rats and rats placed in the chamber and not stimulated revealed a rise in circulating ir-beta-EP: the magnitude of this rise did not, however, differ between these groups. Levels of ir-Met-enkephalin, ir-Leu-enkephalin and ir-dynorphin A were modified neither in the PAG nor in other CNS tissues. The data demonstrate that electrical stimulation of the midbrain PAG selectively influences (presumably activates) pools of beta-EP therein. Together with our finding that destruction of PAG-localized beta-EP neurones to block stimulation-analgesia, the data suggest that an activation of intrinsic pools of beta-EP underlies stimulation-produced analgesia elicited from the PAG in the rat.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dynorphins / metabolism
  • Electric Stimulation Therapy*
  • Endorphins / metabolism*
  • Enkephalin, Leucine / metabolism
  • Enkephalin, Methionine / metabolism
  • Locomotion
  • Male
  • Periaqueductal Gray / metabolism*
  • Prolactin / metabolism
  • Rats
  • Rats, Inbred Strains
  • Sensory Thresholds
  • Transcutaneous Electric Nerve Stimulation*
  • beta-Endorphin


  • Endorphins
  • Enkephalin, Methionine
  • Enkephalin, Leucine
  • beta-Endorphin
  • Dynorphins
  • Prolactin