Effects of pentazocine and other opioids on the potassium-evoked release of [3H]noradrenaline from guinea pig cortical slices.
Noradrenaline release and its modulation via presynaptic opioid receptors were examined in guinea pig cortical slices. Slices preloaded with [3H]noradrenaline were superfused in the presence of desipramine (1 microM) and were stimulated by 16 mM K+. 1-Pentazocine inhibited the K+-evoked release of [3H]noradrenaline in a dose-dependent manner (3 x 10(-7)-10(-5) M), while d-pentazocine did not inhibit. This inhibitory effect of 1-pentazocine was antagonized by Mr 2266 (10(-6) M) but not by naloxone (10(-6) M). Among other opioids, dynorphin A-(1-13) and ethylketocyclazocine (kappa agonists) decreased the K+-evoked release of [3H]noradrenaline. Tyr-D-Ala-Gly-NMe-Phe-Gly-ol (DAGO, mu agonist) also inhibited [3H]noradrenaline release but was less potent than the kappa agonists. [D-Pen2,D-Pen5]enkephalin (DPDPE, delta agonist) and phencyclidine (sigma agonist) had no effects on the stimulated release of [3H]noradrenaline. Thus, it was shown that kappa receptors are the major subtype of opioid receptor involved in modulation of noradrenaline release in guinea pig cortex, and that 1-pentazocine inhibits the K+-evoked release of noradrenaline through activation of these receptors.
Kinouchi
K
K
Department of Anesthesiology, Osaka University Medical School, Japan.
Maeda
S
S
Saito
K
K
Inoki
R
R
Fukumitsu
K
K
Yoshiya
I
I
D000818:Animals; D001575:Benzomorphans / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D010423:Pentazocine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*; D013237:Stereoisomerism
D001575:Benzomorphans; D009292:Narcotic Antagonists; D009294:Narcotics; D009270:Naloxone; C027247:MR 2266; D010423:Pentazocine; D011188:Potassium; D009638:Norepinephrine