Modification of morphine-induced hyperlocomotion and antinociception in mice by clorgyline, a monoamine oxidase-A inhibitor

• Published in: Neurochemical research Vol. 31; no. 6; pp. 829 - 837
• Main Authors: Kitanaka, Nobue, Kitanaka, Junichi, Takemura, Motohiko
• Format: Journal Article
• Language: English
• Published: United States Springer Nature B.V 01.06.2006
• Subjects: Analgesics - pharmacology; Animals; Behavior, Animal - drug effects; Biogenic Monoamines - metabolism; Chromatography, High Pressure Liquid; Clorgyline - pharmacology; Locomotion - drug effects; Male; Mice; Mice, Inbred ICR; Monoamine Oxidase Inhibitors - pharmacology; Morphine - pharmacology
• ISSN: 0364-3190; 1573-6903
• DOI: 10.1007/s11064-006-9087-x

We evaluated the effects of pretreatment with clorgyline, an irreversible monoamine oxidase (MAO)-A inhibitor, on morphine-induced hyperlocomotion and antinociception. A single administration of morphine (30 mg/kg, i.p.) to male ICR mice induced a hyperlocomotion. ANOVA analysis revealed the statistical significance of the morphine effect on horizontal locomotion and of the clorgyline pretreatment x morphine interaction effect, but not of the effect of clorgyline pretreatment. The initial (5 min after challenge) phase of morphine actions vs. saline challenge appeared as if morphine had a strong inhibitory effect on locomotor activity in combination with different doses of clorgyline. The mice administered with morphine in combination of clorgyline (1 and 10 mg/kg) did not show any stereotypic behaviors. Clorgyline at a dose of 0.1 mg/kg but not other doses tested significantly potentiated morphine-induced antinociception evaluated by tail flick but not hot plate test. During the measurements of locomotor activity and antinociception, clorgyline at doses of 1 and 10 mg/kg significantly inhibited monoamine metabolism through MAO. These results suggest that clorgyline showed an inhibitory effect on morphine-induced hyperlocomotion, but not antinociception, through MAO inhibition. There is not a possibility that clorgyline pretreatment enhanced morphine action on motor activity, resulting in the abnormal behavior from hyperlocomotion to stereotypic movements.