ABSTRACT
Aim To investigate the relationship between spinal cord noradrenergic neurons ? 1 adrenoceptors and the spinal analgesia of ketamine. Methods Kunming mice were used. Analgesia tests were investigated with warm water tail flick test. The effects of intrathecal injection (ith) of ketamine (50,100,200 ?g)on tail flick latency of animals were observed. And the effect of pretreatment with intrathecal 6 hydrodoapa(6 OHDA, 6?g ) and ? 1 adrenoceptor antagonist prazosin (5, 15 ?g) or terazosin (5, 15 ?g) , respectively on the spinal analgesia of ketamine (100 ?g,ith) was studied. Results Dose dependent analgesia was observed following ith ketamine (100,200 ?g, P
ABSTRACT
Aim To determine the roles of peripheral ? 1 and ? 2 -adrenoceptors (? 1-AR,? 2-AR) in inhibition of carotid sinus barore ceptor reflex(CSR) induced by intracerebroventricular injection (icv) of histami ne (HA).Methods The left and right carotid sinus regions were i solated from the systemic circulation in 22 male Sprague-Dawley rats anesthetiz ed with pentobarbital sodium.The intracarotid sinus pressure (ISP) was altered in a stepwise ma nner in vivo.ISP-mean arterial pressure (MAP) relationship curve and its ch aracteristic parameters were constructed by fitting to the logistic function wit h five parameters.The changes in CSR performance induced by icv HA and the effec ts of pretreatment with ? 1-AR or ? 2-AR selective antagonist into the per ipheral vein on the responses of CSR to HA were examined.Results icv microinjection of HA (60 ?mol?L -1 in 5 ?l) significantly shifted the ISP-MAP relationship curve upwards (P0.05).Conclusion The intracerebroventricular administration of HA results in a rapid resetting of CSR and a decrease in reflex sensitivity, and the functions of both the peripheral ? 1-AR and ? 2-AR may attenuate CSR resetting induced by icv microinjection of HA. Furthermore,the peripheral ? 1-AR might play an important role in mediating the responses of CSR to central HA.