oaioai:CiteSeerX.psu:10.1.1.592.3981

EFFECTS OF ACTH ON PAIN RESPONSIVENESS IN MICE: INTERACTION WITH MORPHINE

Abstract

SummaryPIntravenous (i.v.) injections of ACTH either enhanced (12.5 pg/kg) or slightly, though not significantly, suppressed (200 pg/kg) jumping in a modified hot plate test (46”C, 5 min exposure) in mice. Similarly, injections of morphine (0.037-0.156 mg/kg) markedly enhanced jumping whereas larger doses (0625-lO.Omg/kg) produced profound analgesia in this test. When administered simultaneously by a single intravenous injection, a larger dose of ACTH (200pg/kg) blocked the hyperalgesic effect of the small dose of morphine (i.e. 0.037 mg/kg). A small dose of ACTH (12.5 pg/kg), which by itself produced significant hyperalgesia, prevented the analgesic action of morphine (0.625 mg/kg). Taken together, the data suggest hat ACTH influences behaviourally-activated pain-controlling systems, possibly by inter-acting with opiate mechanisms in the brain. The ability of ACTH to alter the pharmacological actions of morphine as evident from the present results may be indicative of a requisite physiological function of ACTH in modulating the activity of endogenous opioids. Fragments of the polypeptide hormone, adrenocorti-cotropin (ACTH), appear to exert two diametrically opposite effects on pain responsiveness when adminis-tered centrally in rats. Intraventricular administratio

Similar works

Full text

thumbnail-image
oaioai:CiteSeerX.psu:10.1.1.592.3981Last time updated on 10/29/2017

This paper was published in CiteSeerX.

Having an issue?

Is data on this page outdated, violates copyrights or anything else? Report the problem now and we will take corresponding actions after reviewing your request.