Site specificity in the development of tolerance to stimulation-produced analgesia from the periaqueductal gray matter of the rat.
Pentobarbital-anesthetized rats were subjected to 21 min of continuous electrical stimulation of the caudal periaqueductal gray matter (PAG) at the current threshold for analgesia. Stimulation at ventral PAG sites supported analgesia for only 1 or 2 min in most animals. Stimulation at more dorsal PAG sites supported analgesia for the entire 21 min of stimulation. This demonstration of acute tolerance with continuous ventral, but not more dorsal, PAG stimulation corresponds well with previous evidence suggesting opioid mediation of analgesia from this brain region.
Morgan
M M
MM
Department of Psychology, University of California, Los Angeles 90024-1563.
Liebeskind
J C
JC
D000698:Analgesia; D000818:Animals; D004558:Electric Stimulation; D008297:Male; D010146:Pain / Q000503:physiopathology; D010487:Periaqueductal Gray / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds; D013997:Time Factors