Mu-, but not delta-, opioid receptor-mediated antinociception in mice is attenuated by gamma-irradiation.
Mice were exposed to whole-body irradiation (500 rads) from a 137Cs gamma-source and tested 2 h later for antinociception (tail-flick test) produced by intracerebroventricular administration of morphine or the more delta-selective opioid peptide, [D-Pen2,L-Pen5]enkephalin (DPLPE). Irradiation significantly attenuated the antinociception produced by morphine, but not by DPLPE. These results demonstrate a differential sensitivity of mu- and delta-opioid receptors to gamma-irradiation and, in addition, may be of clinical relevance for cancer patients receiving concurrent radiation therapy and opioid analgesics.
Raffa
R B
RB
Department of Biological Research, Janssen Research Foundation, Spring House, PA 19477.
Mathiasen
J R
JR
Brown
D Q
DQ
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D005720:Gamma Rays; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000528:radiation effects*; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu
D000700:Analgesics; D004745:Enkephalins; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D009020:Morphine; D020881:Enkephalin, D-Penicillamine (2,5)-