Role of Central Serotonergic (5-HT2) Receptor in Blood Pressure Regulation in Rats

Abstract

To investigate the role of the serotonergic nervous system in blood pressure regulation, 5μg of 5-hydroxytryptamine (5-HT) was given i.c.v. before and after 1 μg of i.c.v. xylamidine or 200μg of i.c.v. ketanserin or 200μg of i.v. ketanserin in conscious Wistar Kyoto rats. Also i.v. (0.5, 1, 2μg) or i.c.v. (1μg) phenylephrine (PHE) were given before and after 1μg of i.c.v. xyla-midine. I.c.v. 5-HT elicited a consistent pressor response of approximately 27mHg and slight decrease in heart rate. MAP and heart rate did not change after xylamidine or ketanserin. Whereas pressor response to i.c.v. 5-HT after i.c.v. ketanserin or i.c.v. xylamidine was suppressed, it did not change after i.v. ketanserin. Neither i.c.v. nor i.v. PHE-induced pressor response was influenced by i.c.v. xylamidine pretreatment. These data suggest that the central 5-HT₂ receptor may subserve pressor function in rats.