TY - JOUR
T1 - Involvement of neurokinin receptors in the induction but not the maintenance of mechanical allodynia in rat flexor motoneurones.
AU - Ma, Q. P.
AU - Woolf, C. J.
N1 - Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 1995/8/1
Y1 - 1995/8/1
N2 - 1. Intrathecal (i.t.) injections of the (tachykinin) NK1 receptor agonist, substance P methyl ester (SPME; 20 pmol), or the NK2 receptor agonist, neurokinin A (NKA; 20 pmol), substantially decreased the cutaneous mechanical threshold and markedly enhanced the touch‐evoked response of posterior biceps femoris‐semitendinosus (PBF‐ST) spinal flexor motoneurones in decerebrate‐spinal rats. This cutaneous mechanical reflex allodynia was prevented by pretreatment with the NK1 antagonist RP 67580 (2.28 nmol, i.t.) and the NK2 antagonist MEN 10376 (0.7 nmol, i.t.), respectively. 2. Electrical stimulation of the sural nerve at C fibre strength or cutaneous application of the irritant, mustard oil, produced prolonged cutaneous mechanical allodynia in PBF‐ST motoneurones (15 min and > 1 h, respectively). Pretreatment with RP 67580 but not MEN 10376 prevented this, but when RP 67580 was administered 25 min after the application of mustard oil, the established hypersensitivity of the flexor motor reflex was not reversed. The enantiomer of RP 67580, RP 68651 was without effect. 3. Injection of bradykinin (60 microM, 80 microliters) into the gastrocnemius muscle increased the cutaneous mechanical hypersensitivity of PBF‐ST flexor motoneurones for 40‐50 min. MEN 10376, but not RP 67580, prevented this, but only when administered prior to the bradykinin injection. 4. These results suggest that the induction, but not the maintenance, of cutaneous mechanical allodynia in flexor motoneurones is NK receptor dependent, with cutaneous C fibre conditioning inputs acting via NK1 and muscle C fibre conditioning inputs via NK2 receptor subtypes.
AB - 1. Intrathecal (i.t.) injections of the (tachykinin) NK1 receptor agonist, substance P methyl ester (SPME; 20 pmol), or the NK2 receptor agonist, neurokinin A (NKA; 20 pmol), substantially decreased the cutaneous mechanical threshold and markedly enhanced the touch‐evoked response of posterior biceps femoris‐semitendinosus (PBF‐ST) spinal flexor motoneurones in decerebrate‐spinal rats. This cutaneous mechanical reflex allodynia was prevented by pretreatment with the NK1 antagonist RP 67580 (2.28 nmol, i.t.) and the NK2 antagonist MEN 10376 (0.7 nmol, i.t.), respectively. 2. Electrical stimulation of the sural nerve at C fibre strength or cutaneous application of the irritant, mustard oil, produced prolonged cutaneous mechanical allodynia in PBF‐ST motoneurones (15 min and > 1 h, respectively). Pretreatment with RP 67580 but not MEN 10376 prevented this, but when RP 67580 was administered 25 min after the application of mustard oil, the established hypersensitivity of the flexor motor reflex was not reversed. The enantiomer of RP 67580, RP 68651 was without effect. 3. Injection of bradykinin (60 microM, 80 microliters) into the gastrocnemius muscle increased the cutaneous mechanical hypersensitivity of PBF‐ST flexor motoneurones for 40‐50 min. MEN 10376, but not RP 67580, prevented this, but only when administered prior to the bradykinin injection. 4. These results suggest that the induction, but not the maintenance, of cutaneous mechanical allodynia in flexor motoneurones is NK receptor dependent, with cutaneous C fibre conditioning inputs acting via NK1 and muscle C fibre conditioning inputs via NK2 receptor subtypes.
UR - http://www.scopus.com/inward/record.url?scp=0029098297&partnerID=8YFLogxK
U2 - 10.1113/jphysiol.1995.sp020852
DO - 10.1113/jphysiol.1995.sp020852
M3 - Article
C2 - 7473237
AN - SCOPUS:0029098297
SN - 0022-3751
VL - 486
SP - 769
EP - 777
JO - Journal of Physiology
JF - Journal of Physiology
IS - 3
ER -