Abstract
Tolerance to the antinociceptive effect of morphine is mediated at least in part by morphine's action within the periaqueductal gray (PAG). The objective of the present study was to determine whether both ventral and lateral-dorsal PAG regions contribute to the development of tolerance. It was found that the antinociceptive efficacy of microinjecting morphine (5 microg/0.4 microl) into the ventral but not the lateral-dorsal PAG diminished with successive injections. Control experiments indicated that this decrease was caused by tolerance to morphine and was not a result of cell death caused by repeated microinjections or habituation from repeated behavioral testing. The finding of greater susceptibility of the ventral compared with the lateral-dorsal PAG to the development of tolerance adds to a growing literature distinguishing antinociception from these two regions.
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.
