Release of immunoreactive Met-enkephalin from the spinal cord by intraventricular beta-endorphin but not morphine in anesthetized rats.
Effect of beta-endorphin and morphine injected intraventricularly on the release of immunoreactive Met-enkephalin, Leu-enkephalin and dynorphin1-13 from the spinal cord was studied in anesthetized rats. Intraventricular beta-endorphin, 16 micrograms, caused a marked spinal release of immunoreactive Met-enkephalin and to a much lesser extent, of immunoreactive Leu-enkephalin while intraventricular morphine, 40 micrograms, did not cause any significant release of immunoreactive enkephalins. The release of immunoreactive Met-enkephalin was not blocked by the pretreatment with 5 mg/kg naloxone, i.p. Immunoreactive dynorphin1-13 was not released by either beta-endorphin or morphine. High performance liquid chromatographic analysis indicated that immunoreactive Met-enkephalin released by beta-endorphin had a retention time identical to [3H]Met-enkephalin. These findings in conjunction with previous pharmacological studies suggest different modes of pharmacological action for beta-endorphin and morphine.
Tseng
L F
LF
Higgins
M J
MJ
Hong
J S
JS
Hudson
P M
PM
Fujimoto
J M
JM
D000818:Animals; D004399:Dynorphins / Q000378:metabolism; D004723:Endorphins / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000378:metabolism*; D007276:Injections, Intraventricular; D007278:Injections, Spinal; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010446:Peptide Fragments / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism*; D001615:beta-Endorphin
D004723:Endorphins; D010446:Peptide Fragments; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; C026843:dynorphin (1-13); D004399:Dynorphins; D009020:Morphine