Lesions of the pedunculopontine tegmental nucleus abolish catalepsy and locomotor depression induced by morphine

• Published in: Brain research Vol. 662; no. 1; pp. 134 - 140
• Main Authors: Olmstead, Mary C., Franklin, Keith B.J.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 31.10.1994; Amsterdam Elsevier; New York, NY
• Subjects: Acoustic Stimulation; Animals; Behavior, Animal - drug effects; Biological and medical sciences; Brainstem; Catalepsy; Catalepsy - chemically induced; Fundamental and applied biological sciences. Psychology; Locomotion; Male; Mesencephalon - anatomy & histology; Mesencephalon - physiology; Morphine - pharmacology; Motor Activity - drug effects; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Muscle Tonus - drug effects; Muscle Tonus - physiology; N-Methylaspartate - pharmacology; Opiate; Photic Stimulation; Pons - anatomy & histology; Pons - physiology; PPTg; Rats; Rats, Wistar; Reflex - drug effects; Stimulation, Chemical; Vertebrates: nervous system and sense organs; Opiate; Locomotion; PPTg; Catalepsy; Brainstem; Vertebrata; Mammalia; Rat; Rodentia; Central nervous system; Morphine; Lesion; Tegmentum
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/0006-8993(94)90805-2

The cataleptic and locomotor depressant effects of morphine are mediated by a series of neural structures, all of which project to the pedunculopontine tegmental nucleus (PPTg). To test the idea that the PPTg is also involved in mediating morphine's effect on these behaviours, we examined catalepsy and spontaneous motor activity following bilateral lesions of the PPTg (0.5 μl of 0.1 M N- methyl- d-aspartate infused over 10 min). We also examined the effect of PPTg lesions on motor functioning by observing sensorimotor responses, limb use, muscle tone and locomotion. PPTg lesions completely abolished the catalepsy and decreased activity that normally follows morphine administration. In addition lesioned animals exhibited increased muscle tone, and impairments in limb use and righting reflexes. Although the deficits were subtle, these results confirm that damage to the PPTg is associated with motor abnormalities.