Korner P I, Head G A
Chest. 1983 Feb;83(2 Suppl):335-8.
Synaptic release of transmitter from central noradrenergic (NA) and serotonergic (5HT) neurons was studied in intact and pontine decerebrate unanesthetized rabbits, following intracisternal injections of the selective neurotoxic drugs 6-hydroxydopamine (6-OHDA) and 5,6-dihydroxytryptamine (5,6-DHT). The NA and 5HT neurons both raise blood pressure through a suprapontine pathway, with 5HT neurons in series with NA neurons. Descending bulbospinal fibers have antagonistic effects on blood pressure, with NA release lowering blood pressure and 5HT release increasing it. The two transmitters also have antagonistic effects on the cardiac vagus, with NA neurons increasing vagal activity and 5HT neurons inhibiting it. Our results suggest that both NA and 5HT neurons contribute to the cardiovascular effects of clonidine. The actions of clonidine on blood pressure and heart rate mimic the effects of NA and are opposite those of 5HT released at synaptic sites in the bulb and spinal cord.
在完整的和脑桥去大脑未麻醉的兔子中，通过脑池内注射选择性神经毒性药物6-羟基多巴胺（6-OHDA）和5,6-二羟基色胺（5,6-DHT），研究了中枢去甲肾上腺素能（NA）和5-羟色胺能（5HT）神经元的递质突触释放。NA和5HT神经元均通过脑桥上的通路升高血压，5HT神经元与NA神经元串联。下行的延髓脊髓纤维对血压有拮抗作用，NA释放降低血压，5HT释放升高血压。这两种递质对心脏迷走神经也有拮抗作用，NA神经元增加迷走神经活动，5HT神经元抑制迷走神经活动。我们的结果表明，NA和5HT神经元均参与可乐定对心血管的作用。可乐定对血压和心率的作用模拟了NA的作用，与延髓和脊髓突触部位释放的5HT的作用相反。
