effective in treatment of pain but, its utility is hindered by the development of tolerance to its
analgesic effects. Orexin A and B (hypocretin 1 and 2) discovered in 1998 and projected to
large areas of the brain regions involved in the tolerance and dependence to morphine. The
attenuated withdrawal syndrome seen in orexinknock-out mice suggests that such
regulation of orexin neurons may be an important contributor to morphine physical …