Abstract
Publisher Summary This chapter discusses the effects of morphine given in the brain stem on the activity of dorsal horn nociceptive neurons. Morphine activates descending systems of inhibition, and contributes to the analgesia produced. Whether given intracerebroventricularly or intracerebrally, morphine inhibits responses to nociceptive stimuli, including nociceptive withdrawal reflexes organized segmentally, consistent with the activation by morphine of a descending system(s) of inhibition. Microinjection of morphine into the midbrain periaqueductal gray (PAG) or medullary nucleus raphe magnus (NRM), two sites in the brain stem considered important to endogenous systems of pain control, inhibits responses in analgesiometric tests organized either spinally or supraspinally. Bulbospinal monoaminergic systems are activated by morphine microinjected into either the PAG or NRM and antinociceptive effects of the morphine, whether given systemically or intracerebrally, are attenuated by lesions in the medulla or spinal cord and by receptor antagonists administered into the intrathecal space.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
