Faculty Collaboration Database

Characterization of responses of T2-T4 spinal cord neurons to esophageal distension in the rat. J Neurophysiol 1993 Mar;69(3):868-83

Date

03/01/1993

Pubmed ID

8385199

DOI

10.1152/jn.1993.69.3.868

Scopus ID

2-s2.0-0027340032 (requires institutional sign-in at Scopus site)   63 Citations

Abstract

1. Three hundred fifty neurons in the T2-T4 spinal segments of 38 intact, pentobarbital sodium-anesthetized, pancuronium-paralyzed male rats were examined for somatic receptive fields and responses to midthoracic esophageal distension (ED). Recordings were made at a depth of 0.1-1.45 mm from the dorsal spinal cord surface and from the midline to approximately 1.0 mm lateral. 2. Fifty-six of the 350 total neurons (16%) responded to ED, produced by air inflation of a latex balloon (0.5-1.5 ml). Most of these 56 neurons (84%) were excited by ED, and all except one were excited at a short latency (< 2 s) to stimulus onset. The response to ED in about one-half of all excited neurons terminated abruptly with termination of the stimulus; the other neurons exhibited an afterdischarge of 5 to > 80 s. Repeated ED at a constant intensity (1.25 ml, 30 s every 6 min) produced stable and reproducible responses of neurons excited by ED. Twenty-one percent of neurons that responded to ED were antidromically invaded from the spinomedullary junction. 3. Graded ED (0.5-1.5 ml, 30 s every 6 min) produced linear and accelerating stimulus-response functions in the 29 neurons tested. The mean threshold for distension, determined with a least-squares regression analysis, was extrapolated to near 0.5 ml of distending volume, and no difference in response threshold was found between neuronal groups with or without after-discharge. 4. The spontaneous activity of 7 of the 56 neurons (12.5%) that responded to ED was inhibited by the stimulus. Stimulus-response functions for four neurons inhibited by ED were intensity dependent. The spontaneous activity of these neurons was inhibited to a mean of 24.5% of the prestimulus control by 1.25 ml ED. 5. Two neurons of the total sample of 56 (3.5%) responded to ED (1.50 ml) in a biphasic excitatory-inhibitory manner. The excitatory component of excitatory-inhibitory neurons encoded the intensity of ED; the inhibitory component during the second half of ED was apparent only at greater distending volumes (1.25-1.5 ml). 6. Somatic receptive fields were found for 303/350 neurons, and 98% were located on the thorax and proximal forearm (all ipsilateral). Five neurons in T2-T4 spinal segments had their cutaneous receptive fields located on caudal parts of the body (tail, hindleg, scrotum).(ABSTRACT TRUNCATED AT 400 WORDS)

Author List

Euchner-Wamser I, Sengupta JN, Gebhart GF, Meller ST

Author

Jyoti N. Sengupta PhD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Afferent Pathways
Animals
Autonomic Nervous System
Brain Stem
Esophagus
Ganglia, Spinal
Male
Mechanoreceptors
Neural Inhibition
Neurons
Nociceptors
Nodose Ganglion
Rats
Rats, Sprague-Dawley
Reaction Time
Skin
Spinal Cord
Synaptic Transmission
Vagus Nerve