Tachykinins mediate changes in spinal reflexes after activation of unmyelinated muscle afferents in the rat.
The effect of intrathecally applied tachykinin antagonist D-NicLys1, 3-Pal3, D-Cl2Phe5, Asn6, D-Trp7.9, Nle11-substance P, spantide II, on the long-term increase of spinal cord excitability after activation of unmyelinated muscle afferents was studied in decerebrate, spinalized, unanaesthetized rats. A conditioning stimulus train (1 Hz, 20 s) that activated unmyelinated fibres in the gastrocnemius muscle nerve facilitated the flexor reflex for about 1 h, which was strongly blocked by pretreatment with spantide II (3 micrograms). The present results indicate that the facilitation of the flexor reflex by conditioning stimulation of a muscle nerve is mediated by tachykinins and possibly other neuropeptides which may be released from the central terminals of these unmyelinated afferents.
Wiesenfeld-Hallin
Z
Z
Department of Clinical Physiology, Karolinska Institute, Huddinge University Hospital, Sweden.
Xu
X J
XJ
Håkanson
R
R
Feng
D M
DM
Folkers
K
K
D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D004553:Electric Conductivity / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D009132:Muscles / Q000187:drug effects / Q000294:innervation* / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000502:physiology*; D013127:Spinal Nerves / Q000187:drug effects / Q000502:physiology*; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D015320:Tachykinins / Q000502:physiology*
D000700:Analgesics; D015320:Tachykinins; C065446:spantide II; D013373:Substance P