Objective To study the contents of immunoreactive
adrenocorticotropin hormone (Ir
ACTH) and immunoreactive β endorphine (Ir β
EP) in the
hippocampus and pain behavior of
acute morphine tolerant
rats and the effect of Rhizoma Paridis saponins (RPS) on the contents and the behavior. Methods Five consecutive subcutaneous injections of morphine hydrochloric acid (6 mg/kg) were given to Wistar rats at 2 h intervals to establish the acute morphine tolerance rat model. The contents of ACTH and β EP were determined by radioimmunoassay. The pain threshold was determined with hot water induced tail flick test and radiant heat induced paw lift test. Results The contents of ACTH and β EP were increased in the rats with single dose of morphine but decreased in those with 5 consecutive injections. RPS was found to suppress this decrease and increase the antinociception effect of morphine in acute morphine tolerant rats. Conclusion RPS can enhance the efficiency of morphine after the acute morphine tolerance was established and affect this establishment by its actions on ATCH and β EP in the hippocampus.
More abstracts about the Effects of Rhizoma Paridis saponins on the pain threshold and Ir-ACTH and Ir-β-EP contents in hippo