An augmented CO2 chemoreflex and overactive orexin system are linked with hypertension in young and adult spontaneously hypertensive rats

摘要

Key points class="unordered" style="list-style-type:disc" id="tjp7264-list-0001">Activation of central chemoreceptors by CO2 increases sympathetic nerve activity (SNA), arterial blood pressure (ABP) and breathing. These effects are exaggerated in spontaneously hypertensive rats (SHRs), resulting in an augmented CO2 chemoreflex that affects both breathing and ABP.The augmented CO2 chemoreflex and the high ABP are measureable in young SHRs (postnatal day 30–58) and become greater in adult SHRs.Blockade of orexin receptors can normalize the augmented CO2 chemoreflex and the high ABP in young SHRs and normalize the augmented CO2 chemoreflex and significantly lower the high ABP in adult SHRs.In the hypothalamus, SHRs have more orexin neurons, and a greater proportion of them increase their activity with CO2.The orexin system is overactive in SHRs and contributes to the augmented CO2 chemoreflex and hypertension. Modulation of the orexin system may be beneficial in the treatment of neurogenic hypertension.