Central cardiovascular regulation and 5-hydroxytryptamine receptors

Evidence is provided to support the view that central 5-HT1A and 5-HT2 receptors are the major receptor subtypes important In cardiovascular regulation. Data are also provided to implicate 5-HT1B/1D/1F receptors in central cardiovascular regulation. Activation of 5-HT2 receptors generally causes sympathoexcitation and a rise in blood pressure and this is mainly mediated by 5-HT2A receptors. However, presympathetic vasomotor neurones located in the hindbrain (RVLM), controlling sympathetic outflow to the heart, are not activated in the same way as other presympathetic vasomotor neurones, although activation of 5-HT2 receptors located in the midbrain can activate sympathetic outflow to the heart. Furthermore, at least In the rat, these midbrain 5-HT2A receptors are also responsible for the release of vasopressin by activation of a central angiotensinergic pathway. The ability of vasopressin directly and/or indirectly to modify renal sympathetic outflow involves the activation of central 5-HT2B receptors, which in turn, when activated via the i.c.v. route, can cause selective renal sympathoexcitation. Evidence is also provided which indicates that the reflex control of parasympathetic outflow to the heart and to other organs involves central 5-HT1A receptors located in the vicinity of these preganglionic vagal neurones. Finally, 5-HT3 receptors are implicated in the afferent regulation of central sympathetic and parasympathetic tone. (C) 2001 Elsevier Science Inc.