title: Adrenaline involvement in the presynaptic beta-adrenoceptor-mediated mechanism of dopamine release from slices of the rat hypothalamus.
abstract: Slices of rat hypothalamus were superfused and endogenous release of dopamine (DA) was measured by high performance liquid chromatography combined with electrochemical detection. The K+ (20 mM)-evoked release in the presence of tetrodotoxin was Ca2+-dependent. The evoked release was facilitated by a beta-agonist, isoproterenol and this effect was completely abolished by a beta-antagonist, 1-propranolol. Isoproterenol also concentration-dependently facilitated the electrically (at 5Hz) evoked release of DA. The pretreatment with 1-propranolol, beta 1-antagonist, atenolol and beta 2-antagonist, butoxamine shifted the concentration-effect curve of isoproterenol to the right. On the other hand, beta 1-agonist, tazolol, beta 2-agonist, salbutamol and low concentration (10(-9) M) of adrenaline also facilitated the release. 1-Propranolol alone reduced the electrically (at 2 Hz) evoked release, and this effect was completely abolished when the adrenaline content in the brain was drastically reduced by use of a potent PNMT inhibitor, DCMB. These findings suggest that in the rat hypothalamus adrenaline released from adrenaline-containing nerve terminals probably modulates DA release via presynaptic beta 1- and beta 2-adrenoceptors on DA nerve terminals.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D002078:Butoxamine / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000378:metabolism*; D004837:Epinephrine / Q000502:physiology*; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D002078:Butoxamine; D013779:Tetrodotoxin; D001262:Atenolol; D011433:Propranolol; C002268:tazolol; D007545:Isoproterenol; D000420:Albuterol; D004298:Dopamine; D004837:Epinephrine