Central pressor effect of parathyroid hormone-related protein in conscious rats

Although the parathyroid hormone-related protein gene is widely expressed in the central nervous system, the role of this protein in blood pressure is unknown. This article examines whether parathyroid hormone-related protein is involved in the central regulation of blood pressure. An intraventricularly injected solution of parathyroid hormone-related protein elicited a dose-dependent increase of mean arterial pressure accompanied by a decrease of heart rate in conscious Sprague-Dawley rats. An anti-parathyroid hormone-related protein monoclonal antibody, given in an intraventricularly injected solution, blocked the pressor effect of parathyroid hormone-related protein. Furthermore, this pressor effect of parathyroid hormone-related protein was also abolished after pretreatment by intravenous administration of either hexamethonium bromide or doxazosin mesylate. These results suggest that central parathyroid hormone-related protein is implicated in the regulation of blood pressure, and that this effect may be mediated through sympathetic activation.