Interleukin-1 beta induces long-term increase of axonally transported opiate receptors and substance P.

Interleukin-1 is known to exert pleiotropic effects in host defence mechanisms and in inflammation. Chronic pain, inflammation and interleukin-1 beta enhance the production of substance P. Recently, axonal transport of opiate receptors was found to increase in rat sciatic nerves in the model of Freund's adjuvant-induced arthritis. Here we show that a single intraplantar injection of interleukin-1 beta is able to enhance the axonal transport of mu and kappa opiate receptors and substance P. Indeed, their accumulation was markedly increased in the proximal part of ligated sciatic nerves, but only in the paw injected with interleukin-1. The time course revealed a delayed onset and, more importantly, a long-term increase lasting at least six days, which is in contrast with the short-term pyrogenic effect of interleukin-1. Pretreatment of rats with capsaicin or administration of dexamethasone completely prevented the interleukin-1 beta effect. The present results suggest that interleukin-1 beta may serve as a mediator to sensitize nociceptors in chronic inflammation and possibly in hyperalgesia through long-term changes in neuronal plasticity.

Blockade by oral or parenteral RPR 100893 (a non-peptide NK1 receptor antagonist) of neurogenic plasma protein extravasation within guinea-pig dura mater and conjunctiva.

1. The ability of an NK1 receptor antagonist, RPR 100893, and its enantiomer, RPR 103253 to block neurogenic plasma protein extravasation in guinea-pig dura mater and conjunctiva was assessed following 125I-labelled bovine serum albumin ([125I]-BSA, 50 muCi kg-1, i.v.) and unilateral electrical stimulation of the trigeminal ganglion (0.6 mA, 5 ms, 5 Hz, 5 min) or capsaicin administration (150 micrograms kg-1, i.v.). 2. When administered p.o. 60 min prior to electrical stimulation, RPR 100893 (> or = 0.1 microgram kg-1) decreased plasma protein extravasation in dura mater in a dose-dependent manner, whereas the enantiomer (10 or 100 micrograms kg-1, p.o.) was inactive. 3. When given i.v. 30 min prior to electrical stimulation, RPR 100893 (> or = 0.5 ng kg-1) significantly inhibited plasma protein extravasation in the dura mater evoked by electrical stimulation in a dose-dependent manner. 4. RPR 100893 (100 micrograms kg-1, p.o.) also reduced the leakage when given 45 min before the guinea-pigs were killed and 10, 40 and 80 min after electrical trigeminal stimulation. 5. RPR 100893 given p.o. dose-dependently inhibited capsaicin-induced plasma protein extravasation with ID50S of 7.4 micrograms kg-1 and 82 micrograms kg-1 for dura mater and conjunctiva, respectively. 6. These results are consistent with the contention that NK1 receptors mediate neurogenic plasma protein leakage following trigeminal stimulation, and suggest that NK1 receptor antagonists of the perhydroisoindolone series may be useful for treating migraine and cluster headaches.

Inhibition of neurogenic inflammation in the meninges by a non-peptide NK1 receptor antagonist, RP 67580.

RP 67580, a non-peptide NK1 receptor antagonist, inhibited in a stereoselective and dose-dependent manner plasma extravasation caused in the dura mater by intravenous injection of capsaicin in guinea-pigs and of exogenous substance P in rats (ED50 = 35 and 2.5 micrograms/kg i.v., respectively). In the two species, RP 67580 appeared to be more effective in the dura mater than in the peripheral organs. These results indicate that selective NK1 receptor antagonists could be potentially effective for the treatment of migraine headache.

A non-peptide NK1-receptor antagonist, RP 67580, inhibits neurogenic inflammation postsynaptically.

1. The non-peptide neurokinin NK1-receptor antagonist, RP 67580 (3aR, 7aR), a perhydroisoindolone derivative, powerfully reduced plasma extravasation in rat hind paw skin induced by local application of xylene (ID50 = 0.03 mg kg-1, i.v.) or capsaicin (ID50 = 0.06 mg kg-1, i.v.), or by i.v. injection of exogenous substance P (SP) or septide ([pGlu6,Pro9]SP(6-11)) (ID50 = 0.04-0.05 mg kg-1, i.v.). RP 67580 (1 mg kg-1, i.v.) also abolished capsaicin-induced nasal fluid hypersecretion (by 82 +/- 5%). These effects were found to be stereospecific, the enantiomer, RP 68651 (3aS, 7aS), being inactive at 1 mg kg-1, i.v. 2. In rats neonatally treated with capsaicin (50 mg kg-1, s.c.), plasma extravasation induced by SP was significantly increased (by 43 +/- 7%). RP 67580 (1 mg kg-1, i.v.) completely inhibited the SP-induced plasma extravasation in capsaicin neonatally treated-animals, as it did in control animals. This result suggests that RP 67580 acts at the postsynaptic level for the inhibition of plasma extravasation. 3. Opioid receptor agonists, mu-(morphine) and kappa-(PD-117302) at 10 mg kg-1, s.c., in contrast to NK1-receptor antagonists, did not inhibit plasma extravasation induced by exogenous SP. They were, however, partially effective against plasma extravasation induced by electrical nerve stimulation (74 +/- 4% and 48 +/- 9% inhibition at 10 mg kg-1, s.c. of morphine and PD-117302, respectively, compared to 90 +/- 3% inhibition obtained with RP 67580, 3 mg kg-1, s.c.). These results indicate the presynaptic action of opioid receptor agonists, in contrast to the postsynaptic action of NK1-receptor antagonists for the inhibition of plasma extravasation.4. Ligature of the saphenous nerve distal to the point of electrical stimulation, local application of lignocaine to the saphenous nerve, neonatal capsaicin pretreatment, and colchicine at very low doses(120 microg kg-1 day-1 given for 3 days) were found to prevent plasma extravasation elicited by electrical nerve stimulation.5. The foregoing results demonstrate that the non-peptide NK1-receptor antagonist, RP67580, is a potent inhibitor of plasma extravasation induced in skin by NK1-receptor agonists, by local application of chemical irritants (capsaicin or xylene) or by electrical nerve stimulation. Moreover, opioid receptor agonists and colchicine inhibit plasma extravasation induced by electrical nerve stimulation but not that elicited by exogenous SP. Therefore, it is possible to inhibit neurogenic inflammation either at the presynaptic level with opioid receptor agonists and colchicine, or at the postsynaptic level withNK1-receptor antagonists, and that the new non-peptide NK1-receptor antagonists may have a great potential for alleviation of inflammation in various pathological syndromes in man.

Polyclonal antibodies against the rat NK1 receptor: characterization and localization in the spinal cord.

We have developed antibodies against the NK1 receptor and have investigated its cellular distribution. Rabbit polyclonal antibodies were generated against peptide (19-32) of the rat brain NK1 receptor. They were very specific to the NK1 site as shown by ELISA against various epitopes of NK1, NK2 and NK3 receptors and by immunoblotting of proteins from bacteria transfected with rat brain NK1 receptor cDNA and from rat cortex. Determining how immunostained NK1 receptors are distributed in the rat spinal cord made it possible to identify the cellular structures on which NK1 receptors are located and where they form synapses with SP terminals. In the superficial layers of the dorsal horn, the NK1 receptors appeared mainly of dendritic nature and were, like SP, abundant. In the deep layers of the dorsal horn and in the ventral horn, they were associated mostly with cell bodies.

Comparison in different tissue preparations of the in vitro pharmacological profile of RP 67580, a new non-peptide substance P antagonist.

We describe the effects of RP 67580, a new non-peptide substance P (SP) antagonist, on tachykinin-induced contractions of guinea-pig ileum, trachea and urinary bladder, rabbit pulmonary artery and rat portal vein. All NK1 agonists tested (SP, Septide, SPOMe and [Pro9]SP) contracted guinea-pig ileum, trachea and urinary bladder (pD2 = 7.5 to 9.1), but they had no effect on rabbit pulmonary artery or rat portal vein (pD2 < 6). RP 67580 inhibited these effects: guinea-pig ileum, pA2 = 7.1 to 7.6; guinea-pig trachea and urinary bladder, pKB = 6.3 to 6.8. The difference in RP 67580 activity in these tissues might be due to the existence of subtypes of NK1 receptors. RP 67580 (1 microns) did not affect the contractions induced by the two NK2 agonists, NKA and [Lys5, MeLeu9, Nle10]NKA(4-10) (pA2 < 6), except in guinea-pig ileum (pA2 = 7.3-7.5) where these two NK2 agonists interact apparently with NK1 receptors. In the tissue preparations used, RP 67580 (1 micron) was without effect on contractions induced by the NK3 agonists: NKB and senktide. These results indicate the high selectivity for NK1 receptors of RP 67580. In all cases, similar results were obtained with another non-peptide SP antagonist, (+/-) CP-96,345. The present work provides further evidence that RP 67580 and (+/-) CP-96,345 exert in vitro a potent, selective and competitive antagonistic action on NK1 receptors and suggests the existence of at least two distinct NK1 receptor subtypes in some guinea-pig peripheral organs.

Distribution of neurokinin B in rat spinal cord and peripheral tissues: comparison with neurokinin A and substance P and effects of neonatal capsaicin treatment.

In the present study, highly specific radioimmunoassays were developed and used to measure neurokinin B, neurokinin A and substance P in the rat spinal cord and various peripheral tissues. The results are as follows. (1) Neurokinin B and neurokinin A were distributed all along the rostrocaudal axis of the spinal cord, as is substance P, and were more concentrated in the dorsal than in the ventral region. (2) Substance P was more abundant in the central and peripheral nervous tissues than neurokinin A, while in certain peripheral organs, neurokinin A was more abundant than substance P. In the spinal cord, neurokinin B concentrations were lower than those of the other two tachykinins. (3) In contrast to neurokinin A and substance P, neurokinin B was not detected in any of the peripheral tissues examined. (4) Capsaicin treatment reduced by half neurokinin A and substance P concentrations in the dorsal region of the spinal cord, the dorsal root ganglia and the sciatic nerve, but was without effect on neurokinin B concentrations in the spinal cord. Neurokinin A, like substance P, may therefore have an important function in the transmission of sensory information, particularly in nociceptive transmission from the periphery to the spinal cord and in peripheral neurogenic inflammation. In contrast, since neurokinin B was not found in the sensory neurons, it is not likely to have these functions, but may perhaps control them.