147581 - profiling the effects.pdf (1.28 MB)
Profiling the effects of repetitive morphine administration on motor behavior in rats
journal contribution
posted on 2023-05-21, 03:52 authored by Alok PaulAlok Paul, Nuri GuvenNuri Guven, Dietis, NEfficient repetitive clinical use of morphine is limited by its numerous side effects, whereas analgesic tolerance necessitates subsequent increases in morphine dose to achieve adequate levels of analgesia. While many studies focused on analgesic tolerance, the effect of morphine dosing on non-analgesic effects has been overlooked. This study aimed to characterize morphine-induced behavior and the development and progression of morphine-induced behavioral tolerance. Adult male Sprague–Dawley rats were repetitively treated with subcutaneous morphine for 14 days in two dose groups (A: 5 mg/kg/day (b.i.d.) → 10 mg/kg/day; B: 10 mg/kg/day (b.i.d.) → 20 mg/kg/day). Motor behavior was assessed daily (distance traveled, speed, moving time, rearing, rotation) in an open-field arena, before and 30 min post-injections. Antinociception was measured using tail-flick and hot-plate assays. All measured parameters were highly suppressed in both dosing groups on the first treatment day, followed by a gradual manifestation of behavioral tolerance as the treatment progressed. Animals in the high-dose group showed increased locomotor activity after 10 days of morphine treatment. This excitatory phase converted to an inhibition of behavior when a higher morphine dose was introduced. We suggest that the excitatory locomotor effects of repetitive high dose morphine exposure represent a signature of its behavioral and antinociceptive tolerance.
History
Publication title
MoleculesVolume
26Issue
4Pagination
1-14ISSN
1420-3049Department/School
School of Pharmacy and PharmacologyPublisher
Molecular Diversity Preservation InternationalPlace of publication
Matthaeusstrasse 11, Basel, Switzerland, Ch-4057Rights statement
Copyright 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).Repository Status
- Open