Comparison of the effect of intrathecal endomorphin-1 and endomorphin-2 on spinal cord excitability in rats.
We examined and compared the effects of intrathecal (i.t.) endomorphin-1 and endomorphin-2 on the nociceptive flexor reflex in decerebrate, spinalized, unanesthetized rats. I.t. endomorphin-1 and -2 induced a dose-dependent depression of the flexor reflex with an initial brief facilitatory effect. The magnitude of reflex facilitation and depression was similar between endomorphin-1 and -2, but the duration of depression was significantly longer for endomorphin-1 than endomorphin-2. The results suggested that the spinal antinociceptive effects of endomorphin-1 and -2 are similar, with endomorphin-1 being more resistant to enzymatic degradation.
Grass
Stefan
S
Department of Medical Laboratory Sciences and Technology, Division of Clinical Neurophysiology, Karolinska Institutet, Huddinge University Hospital, 141 86 Stockholm, Sweden. stefan.grass@labtek.ki.se
Xu
Isabella Shi
IS
Wiesenfeld-Hallin
Zsuzsanna
Z
Xu
Xiao Jun
XJ
D000344:Afferent Pathways / Q000187:drug effects / Q000378:metabolism; D000701:Analgesics, Opioid / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002268:Carboxypeptidases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D007278:Injections, Spinal; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009412:Nerve Fibers / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism* / Q000494:pharmacology; D010146:Pain / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000378:metabolism; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D000701:Analgesics, Opioid; D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105293:endomorphin 1; C105294:endomorphin 2; D002268:Carboxypeptidases