Kappa opiate receptors mediate tail-shock induced antinociception at spinal levels

摘要: Previous work has demonstrated that 3 pharmacologically and neuroanatomically distinct analgesia systems can be sequentially activated by increasing numbers of transcutaneous tail-shock. To date, the categorization early (after 2 tail-shocks) late 80-100 analgesias as opiate-mediated been based on ability systemic naltrexone morphine tolerance to block these effects. In contrast, observed after 5-40 tail-shocks is unaffected manipulations, leading its non-opiate. The present following companion paper were aimed at identifying neuroanatomical loci which endogenous opiates exert their analgesic effects in this tail-shock paradigm and, further, identify opiate receptor subtypes are involved. experiments included focus role spinal induced analgesia. first experiment demonstrates parameters used do not directly activate pain suppressive circuitry within cord, but rather centrifugal modulation originating brain. last two examine effect intrathecal microinjection either (a relatively non-selective antagonist), binaltorphimine (kappa Cys2-Tyr3-Orn5-Pen7-amide (CTOP) (mu or naltrindole (delta antagonist). Taken together, latter demonstrate both shocks) mediated kappa receptors cord.