Descending modulation of thoracic visceroreceptive transmission by C1-C2 spinal neurons.
Extracellular potentials of single T3 neurons were recorded in pentobarbital anesthetized male rats. Thoracic esophageal distension (ED, 0.3-0.4 ml, 20 s) and intrapericardial injection of bradykinin (BK, 10(-5) M, 0.2 ml, 1 min) were used as noxious visceral stimuli. Chemical activation of C1-C2 neurons with glutamate pledgets (1 M, 1-3 min) decreased background activity and/or excitatory responses of 26/35 (74%) neurons to ED and 34/44 (77%) neurons to BK. After spinal transection at rostral C1 in five animals, glutamate at C1-C2 still significantly reduced excitatory responses of five neurons to BK. Data showed that intraspinal descending modulation of C1-C2 neurons primarily produced descending inhibition of excitatory responses of thoracic spinal neurons to noxious visceral stimuli.
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Department of Physiology, University of Oklahoma Health Sciences Center, P.O. Box 26901, Oklahoma City, OK 73190, United States. chao-qin@ouhsc.edu
Kranenburg
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Foreman
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D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002574:Cervical Vertebrae; D004347:Drug Interactions; D004947:Esophagus / Q000502:physiology*; D018698:Glutamic Acid / Q000494:pharmacology; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000166:cytology*; D013119:Spinal Cord Injuries / Q000503:physiopathology
D018698:Glutamic Acid; D001920:Bradykinin