ENDOGENOUS OPIOIDS AND ATP-SENSITIVE POTASSIUM CHANNELS ARE INVOLVED IN THE MEDIATION OF APOMORPHINE-INDUCED ANTINOCICEPTION AT THE SPINAL LEVEL - A BEHAVIORAL-STUDY IN RATS

The effects of intrathecally (i.t.) administered glibenclamide, a bloc ker of adenosine triphosphate-sensitive potassium (K-ATP) channels, or naloxone on the antinociception produced by i.t. apomorphine or morph ine were observed and analyzed in rats by tail-flick (TF) test. The re sults showed that: (1) i.t. apomorphine produced a significant and dos e-dependent antinociception, (2) the antinociception produced by i.t. apomorphine could be blocked dose-dependently by i.t. glibenclamide or naloxone, (3) the antinociception produced by i.t. morphine could als o be blocked dose-dependently by i.t. glibenclamide, The results sugge st that endogenous opioids and ATP-sensitive potassium channels might be involved in the mediation of apomorphine-induced antinociception at the spinal level. (C) 1998 Elsevier Science Inc.