NMDA receptors in the spinal cord exert excitatory influences on spinal motor output in rats.
The role of NMDA receptors in the regulation of spinal motor output was studied in rats. Muscle tension of the hind limbs of decerebrate animals and spinal reflex potentials in anesthetized animals were recorded. Intrathecal injection as well as systemic or intra-4th ventricular injection of (+)-5-methyl-10-11-dihydro-5H-dibenzo[a,d]cyclohepta-5-10-imine maleate (MK-801) reduced muscle tension. Systemic MK-801 did not alter monosynaptic reflexes either in intact or spinal rats, but attenuated polysynaptic reflexes in spinal rats. Thus spinal NMDA receptors participate in spinal motor output in the presence of some specific factors such as descending facilitation and preceding segmental depolarization, which remove the Mg2+ blocking.
Tanabe
M
M
Pharmacology and Molecular Biology Research Laboratories, Sankyo Co, Ltd, Tokyo, Japan. tanabe@shina.sankyo.co.jp
Kaneko
T
T
D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019054:Evoked Potentials, Motor / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006614:Hindlimb / Q000502:physiology; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D007278:Injections, Spinal; D008297:Male; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology*; D012023:Reflex, Monosynaptic / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013126:Spinal Nerve Roots / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate