Dopaminergic control of transmission from group II muscle afferents to spinal neurones in the cat and guinea-pig

• Published in: Experimental brain research 1995-07, Vol.105 (1), p.39-47
• Main Authors: SKOOG, B, NOGA, B. R
• Format: Article
• Language: English
• Subjects: Afferent Pathways - physiology; Animals; Biological and medical sciences; Cats; Dopamine - pharmacology; Dopamine - physiology; Fundamental and applied biological sciences. Psychology; Guinea Pigs; Membrane Potentials - physiology; Muscle Spindles - physiology; Receptors, Dopamine D1 - agonists; Receptors, Dopamine D2 - agonists; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Spinal Cord - drug effects; Spinal Nerve Roots - drug effects; Synaptic Transmission - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/BF00242180

The effects of dopamine and its agonists on transmission from muscle afferents to spinal neurones were investigated in the cat and guinea-pig spinal cord, by measuring the drug effects on the amplitude of monosynaptic field potentials evoked by electrical stimulation of group I and group II muscle afferents. Local iontophoretic application of dopamine, the dopamine D1/D5 agonist SKF-38393 and the D2/D3/D4 agonist quinpirole all depressed the group II field potentials evoked at the base of the dorsal horn. Group II field potentials in the intermediate zone were depressed by dopamine to a similar degree as the dorsal horn field potentials, whereas the dopamine agonists were without effect upon them. The intermediate zone field potentials evoked by group I muscle afferents were not depressed by any of the drugs. The dopamine-evoked depression of the group II-evoked field potentials in the dorsal horn in the guinea-pig spinal cord was reduced by the simultaneous application of haloperidol. The results demonstrate that dopamine receptors mediate the depression of transmission from group II muscle afferents to interneurones in the dorsal horn, but not to neurones in the intermediate zone of the spinal cord.