Substance P and Spinal Neurones

1975 ◽  
Vol 53 (3) ◽  
pp. 423-432 ◽  
Author(s):  
J. L. Henry ◽  
K. Krnjević ◽  
M. E. Morris
Keyword(s):  
Substance P ◽  
Lumbar Spinal Cord ◽  
Field Potentials ◽  
Depressant Effect ◽  
Afferent Pathways ◽  
Spinal Interneurones ◽  
Significant Function ◽  
Excitatory Action ◽  
Spinal Neurones ◽  
Lumbar Spinal

When applied by microiontophoresis, substance P (sP) had a strong, but slow and prolonged excitatory action on nearly half the neurones tested in the lumbar spinal cord of cats. Motoneuronal antidromic field potentials only occasionally showed a significant effect of sP. Cerebral cortical neurones in cats and rats were much less readily excited than spinal interneurones. Some unresponsive units showed evidence of a depressant effect of sP. Although sP may have a significant function in central afferent pathways, it is not likely to be a quickly-acting synaptic transmitter.

An Excitatory Action of Substance P on Cuneate Neurones

1974 ◽  
Vol 52 (3) ◽  
pp. 736-744 ◽  
Author(s):  
K. Krnjević ◽  
Mary E. Morris
Keyword(s):  
Substance P ◽  
Functional Significance ◽  
Pure Substance ◽  
Depressant Effect ◽  
Inhalation Anesthesia ◽  
Primary Afferent ◽  
Excitatory Action ◽  
Afferent Terminals ◽  
Different Sources ◽  
Predominant Effect

Pure Substance P was applied from 7 mM solutions by microiontophoresis to cuneate neurones in cats under barbiturate or inhalation anesthesia. The predominant effect was a slow excitation, beginning after a delay of 10–30 s, reaching a peak some 30 s later, and decreasing only gradually after the end of the application, over 1 min or even longer. It was observed with about half of all the units tested (especially those that were spontaneously active), in all experiments, with several different electrodes, and Substance P obtained from two different sources; and therefore can be considered to reflect a genuine strong but slow depolarizing action. Larger doses of Substance P depressed firing, especially when evoked by glutamate, and, in one experiment, several units showed a mainly depressant effect. This may be explained by a similar slow mechanism of depolarization but with inactivation being predominant. It is concluded that Substance P is unlikely to be the quickly acting transmitter released by primary afferent terminals but its strong excitatory action may be of functional significance in some other respects.

Role of peripheral tissue receptors in stimulation of ventilation by 2,4-dinitrophenol

1979 ◽  
Vol 47 (5) ◽  
pp. 1066-1073 ◽  
Author(s):  
S. Levine
Keyword(s):  
Spinal Cord ◽  
Lumbar Spinal Cord ◽  
Afferent Pathways ◽  
Lumbar Level ◽  
Complete Transection ◽  
Group I ◽  
Group Ii ◽  
Lumbar Spinal ◽  
Quantitative Contribution ◽  
Stimulation Of

Previous workers have demonstrated that hindlimb receptors can mediate some portion of the increase in VE elicited by 2,4-dinitrophenol (DNP). Liang and Hood have recently demonstrated that these hindlimb receptors communicate with the respiratory center via afferent pathways of the lumbar spinal cord. Accordingly, to determine the quantitative contribution of these hindlimb receptors to increases in VE elicited by DNP (4 mg/kg), we compared two groups of animals with respect to ventilatory, metabolic, and thermal responses elicited by this drug. Group I animals underwent complete transection of the spinal cord at the first lumbar level, whereas the spinal cord in Group II animals remained intact. Our results indicate that Group I and Group II animals did not differ with respect to increases in VE, VO2, and rectal temperature elicited by DNP. These results suggest that hindlimb receptors do not play an obligatory role in mediating increases in VE elicited by DNP. Therefore, these observations raise the possibility that multiple afferent pathways may exist for stimulation of VE by DNP.

Spinoparabrachial tract neurons showing substance P receptor-like immunoreactivity in the lumbar spinal cord of the rat

1995 ◽  
Vol 674 (2) ◽  
pp. 336-340 ◽  
Author(s):  
Yu-Qiang Ding ◽  
Masahiko Takada ◽  
Ryuichi Shigemoto ◽  
Noboru Mizuno
Keyword(s):  
Spinal Cord ◽  
Substance P ◽  
Lumbar Spinal Cord ◽  
Substance P Receptor ◽  
Lumbar Spinal

Actions of narcotic analgesics and antagonists on spinal units responding to natural stimulation in the cat

1979 ◽  
Vol 57 (6) ◽  
pp. 652-663 ◽  
Author(s):  
O. Calvillo ◽  
J. L. Henry ◽  
R. S. Neuman
Keyword(s):  
Intravenous Administration ◽  
Lumbar Spinal Cord ◽  
Depressant Effect ◽  
Spinal Level ◽  
Narcotic Analgesics ◽  
Analgesic Effects ◽  
Nociceptive Responses ◽  
Natural Stimulation ◽  
Lumbar Spinal ◽  
A Current

Morphine and morphine-related agents were applied by microiontophoresis in the lumbar spinal cord of spinal cats to single units classified on the basis of their responses to natural cutaneous or proprioceptive stimulation. Opiate application had a current-dependent depressant effect on the ongoing activities of about one-third of the units tested. This effect was observed in laminae I and IV–VI, but only with units responding to noxious cutaneous stimuli: the nociceptive responses were themselves depressed. Excitatory and inhibitory responses to glutamate and γ-aminobutyric acid, respectively, were also depressed. Intravenous administration of the opiates at doses reported to produce analgesia in the cat also depressed only units responding to noxious cutaneous stimuli, including their nociceptive responses. This depression could be reversed by either the iontophoretic application (100 nA) or the intravenous administration (0.1–0.8 mg/kg) of naloxone. These results are interpreted as further evidence that the analgesic effects of opiates are at least partly due to an action at the spinal level.

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