A nitric oxide-dopamine link pathway in organum vasculosum laminae terminalis of rat brain exerts control over blood pressure.
1. Experiments were carried out to explore the possible role played by the nitric oxide (NO) and dopamine (DA) system in the organum vasculosum laminae terminalis (OVLT) of rat brain in arterial pressure regulation. 2. Intracerebroventricular (ICV) administration of NO donors such as hydroxylamine or sodium nitroprusside (SNP) caused an up to 59 mmHg decrease in blood pressure (BP) and a decrease in DA release (measured by nafion coated carbon fibre electrodes in combination with voltammetry) in the OVLT. In contrast, ICV administration of N(G)-nitro-L-arginine methyl ester (L-NAME; a constitutive NO synthase inhibitor) or 7-nitroindazol (a neuronal NO synthase inhibitor) caused an up to 98 mmHg increase in BP and an increase in DA release in the OVLT. 3. Intra-OVLT injection of amphetamine (0.1 - 0.3 mg), SKF 38393 (a DA D(1) receptor agonist; 0.01 - 0.03 mg), or apomorphine (a DA D(2,3) receptor agonist; 0.01 - 0.03 mg) caused an increase in BP. On the other hand, intra-OVLT injection of SCH23390 (a DA D(1) receptor antagonist; 0.005 - 0.020 mg) or haloperidol (0.005 - 0.020 mg) caused a decrease in BP. 4. The pressor effects induced by intra-OVLT administration of L-NAME were attenuated by pretreatment with intra-OVLT injection of haloperidol, SCF23390, or 6-hydroxydopamine. In the contrast, the hydroxylamine-, 8-Br-cGMP- or SNP-induced depressor effects were attenuated by pretreatment with intra-OVLT injection of amphetamine, SKF 38393 or apomorphine. 5. The data suggest that activation of a NO-DA link pathway within the OVLT of rat brain exerts control over blood pressure.
Department of Physiology, National Yang-Ming University, School of Medicine, Taipei, Taiwan 112.
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D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D018491:Dopamine Agonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019811:Hydroxylamine / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
D018491:Dopamine Agonists; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D019811:Hydroxylamine; D009569:Nitric Oxide; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000661:Amphetamine; D019001:Nitric Oxide Synthase; D001058:Apomorphine; D019331:NG-Nitroarginine Methyl Ester; D004298:Dopamine