Berger A, Ramirez A J
Faculty of Pharmacy and Biochemistry, UBA, Argentina.
Hypertension. 1988 Feb;11(2 Pt 2):I182-5. doi: 10.1161/01.hyp.11.2_pt_2.i182.
Since previous data obtained in anesthetized rats supported the idea that the activation of spinal serotonergic receptors induced a hypotensive effect, it was decided to characterize more closely the serotonergic spinal involvement and to elucidate the serotonergic receptor type involved in this effect. After female Wistar rats were anesthetized, the femoral artery (for blood pressure measurement) and vein (for parenteral injection of drugs) were cannulated. An intrathecal catheter was positioned with the tip at the T6-L3 intervertebral space. The results showed that the dose-dependent decrease in mean blood pressure induced by serotonin administered at the T6-L3 level was prevented by giving the serotonergic S2 antagonist ritanserin intravenously. The intravenous administration of 5-methoxy-N,N-dimethyltryptamine, a direct serotonergic agonist, induced a dose-dependent hypotension previously shown to originate at spinal cord level. This effect was prevented by intrathecal administration of ketanserin, an S2-receptor antagonist. The selective agonist of the S1-type receptors, 8-hydroxy-dipropylaminotetralin, given at the same level of the spinal cord, failed to induce any effect on mean blood pressure. The results suggest that the hypotensive effect obtained after the spinal serotonergic activation involves serotonin receptors of the S2 type.
由于之前在麻醉大鼠身上获得的数据支持脊髓5-羟色胺能受体激活可诱导降压作用这一观点，因此决定更深入地研究5-羟色胺能对脊髓的影响，并阐明参与此效应的5-羟色胺能受体类型。对雌性Wistar大鼠进行麻醉后，分别插入股动脉（用于测量血压）和静脉（用于肠胃外注射药物）插管。将鞘内导管尖端置于T6-L3椎间隙。结果显示，静脉注射5-羟色胺能S2拮抗剂利坦色林可阻止在T6-L3水平给予血清素所诱导的平均血压剂量依赖性降低。静脉注射直接5-羟色胺能激动剂5-甲氧基-N,N-二甲基色胺可诱导剂量依赖性低血压，此前已证明这种低血压起源于脊髓水平。鞘内注射S2受体拮抗剂酮色林可阻止此效应。在脊髓同一水平给予S1型受体的选择性激动剂8-羟基二丙基氨基四氢萘，对平均血压未产生任何影响。结果表明，脊髓5-羟色胺能激活后获得的降压效应涉及S2型5-羟色胺能受体。
