INVOLVEMENT OF SUPRASPINAL AND SPINAL CCK RECEPTORS IN THE MODULATIONOF ANTINOCICEPTION INDUCED BY COLD-WATER SWIMMING STRESS IN THE MOUSE

We have previously reported that supraspinally and spinally located CC K receptors are involved in antagonizing supraspinally administered op ioid-induced antinociception. Cold water swimming stress (CWSS) produc es antinociception and opioid receptors are involved in CWSS-induced a ntinociception. The present study was designed to determine if suprasp inal and spinal CCK receptors were involved in modulating the CWSS- in duced antinociception. Antinociception was assessed by the tail-flick test. CWSS caused a profound inhibition of the tail-flick response. Va rious doses of CCK injected intracerebroventricularly (i.c.v.) or intr athecally (i.t.) alone did not show any antinociceptive effect. The i. c.v. or i.t. pretreatment with CCK (0.05-0.5 ng) dose dependently atte nuated the CWSS-induced inhibition of the tail-flick response. In addi tion, i.c.v. pretreatment with lorglumide (0.1-10 pg) but not PD135,15 8 (1-100 pg) dose dependently reversed CCK's inhibition of the tail-fl ick response induced by CWSS. However, both lorglumide and PD135,158 i njected i.t. reversed the antagonism of CCK against the inhibition of the tail-flick response induced by CWSS in a dose-dependent manner. Ou r results suggest that, at the supraspinal level, CCKA but not CCKB re ceptors may be involved in antagonizing the CWSS-induced antinocicepti on. In the spinal cord both CCKA and CCKB receptors appear to be invol ved in antagonizing the CWSS-induced antinociception.