Release of met-enkephalin and its modulation through acetylcholine receptors in the rabbit superior colliculus.
This report presents evidence for the depolarization-dependent release of met-enkephalin from the superior colliculus of the rabbit. Collicular tissue was placed in superfusion chambers and met-enkephalin accumulation in the superfusate was measured by radioimmunoassay. Exposure to high potassium concentrations (30 mM and 56 mM) increased met-enkephalin release. This is the fourth transmitter shown to be released from collicular tissue. Furthermore, we have obtained the first evidence that suggests that met-enkephalin release is susceptible to muscarinic modulation. While the depolarization-dependent release of met-enkephalin was depressed in the presence of atropine (1 microM), hexamethonium (100 microM) did not block the increase of met-enkephalin release induced by high potassium.
Illing
R B
RB
Morphologische Hirnforschung, Universitäts-HNO-Klinik, Freiburg, Federal Republic of Germany.
Nikolarakis
K E
KE
Wichmann
T
T
Spatz
W B
WB
Starke
K
K
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D004744:Enkephalin, Methionine / Q000378:metabolism*; D005260:Female; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D011863:Radioimmunoassay; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology*; D013477:Superior Colliculi / Q000187:drug effects / Q000502:physiology*
D006584:Hexamethonium Compounds; D011950:Receptors, Cholinergic; D018738:Hexamethonium; D004744:Enkephalin, Methionine; D001285:Atropine; D011188:Potassium