The hypernociceptive effects of cytokines [TNF-α, keratinocyte-derived chemokine (KC), and IL-1β] and their participation in carrageenan (Cg)-induced inflammatory hypernociception in mice were investigated. Nociceptor sensitization (hypernociception) was quantified with an electronic version of the von Frey filament test in WT and TNF receptor type 1 knockout mice (TNF-R1–/–). TNF-α-induced hypernociception was abolished in TNF-R1–/– mice, partially inhibited by pretreatment with IL-1 receptor antagonist (IL-1ra) or indomethacin and unaffected by Ab against KC (AbKC) or guanethidine. IL-1ra and indomethacin pretreatment strongly inhibited the hypernociception induced by IL-1β, which was not altered by AbKC or guanethidine or by knocking out TNF-R1. KC-induced hypernociception was abolished by AbKC, inhibited by pretreatment with indomethacin plus guanethidine, and partially inhibited by IL-1ra, indomethacin, or guanethidine. In contrast, KC-induced hypernociception was not altered by knocking out TNF-R1. Cg-induced hypernociception was abolished by administration of indomethacin plus guanethidine, diminished in TNF-R1–/– mice, and partially inhibited in WT mice pretreated with AbKC, IL-1ra, indomethacin, or guanethidine. TNF-α, KC, and IL-1β concentrations were elevated in the skin of Cg-injected paws. The TNF-α and KC concentrations rose concomitantly and peaked before that of IL-1β. In mice, the cytokine cascade begins with the release of TNF-α (acting on TNF-R1 receptor) and KC, which stimulate the release of IL-1β. As in rats, the final mediators of this cascade were prostaglandins released by IL-1β and sympathetic amines released by KC. These results extend to mice the concept that the release of primary mediators responsible for hypernociception is preceded by a cascade of cytokines.

https://www.pnas.org/content/pnas/102/5/1755.full.pdf

A cascade of cytokines mediates mechanical inflammatory hypernociception in mice.

Hypernociceptive role of cytokines and chemokines: targets for analgesic drug development?

The objective of the present investigation was to compare the sensitivity of an electronic nociceptive mechanical paw test with classical mechanical tests to quantify the intensity variation of inflammatory nociception. The electronic pressure-meter test consists of inducing the hindpaw flexion reflex by poking the plantar region with a polypropylene pipette tip adapted to a hand-held force transducer. This method was compared with the classical von Frey filaments test and with the rat paw constant pressure test, a modification of the Randall and Selitto test developed by our group. When comparing the three methods, the electronic pressure-meter and the rat paw constant pressure test, but not the von Frey filaments test, detected time vs treatment interactions in prostaglandin E2 (PGE2)-induced hypernociception. Both methods also detected the PGE2-induced hypernociception in dose- (50-400 ng/paw) and time- (1-4 h) dependent manners, and time vs treatment interactions induced by carrageenin (25-400 microg/paw). Furthermore, the electronic pressure-meter test was more sensitive at early times, whereas the constant pressure test was more sensitive at later times. Moreover, the electronic pressure-meter test detected the dose-dependent antinociceptive effect of local indomethacin (30-300 microg/paw) and dipyrone (80-320 microg/paw) on carrageenin- (200 microg/paw) and PGE2- (100 ng/paw) induced hypernociception, respectively, and also detected the ineffectiveness of indomethacin (300 microg) on the effect of PGE2. Our results show that the electronic pressure-meter provides a sensitive, objective and quantitative mechanical nociceptive test that could be useful to characterize new nociceptive inflammatory mediators and also to evaluate new peripheral analgesic substances.

/pdf/an-electronic-pressure-meter-nociception-paw-test-for-mice-4zityfdfhe.pdf

An electronic pressure-meter nociception paw test for mice

Signaling pathways in sensitization: Toward a nociceptor cell biology.

Over the past few years, a wealth of biochemical and functional data have been gathered on mammalian cGMP-dependent protein kinases (cGKs). In mammals, three different kinases are encoded by two genes. Mutant and chimeric cGK proteins generated by molecular biology techniques yielded important biochemical knowledge, such as the function of the NH2-terminal domains of cGKI and cGKII, the identity of the cGMP-binding sites of cGKI, and the substrate specificity of the enzymes. Genetic approaches have proven especially useful for the analysis of the biological functions of cGKs. Recently, some of the in vivo targets and mechanisms leading to changes in neuronal adaptation, smooth muscle relaxation and growth, intestinal water secretion, bone growth, renin secretion, and other important functions have been identified. These data show that cGKs are signaling molecules involved in many biological functions.

https://www.physiology.org/doi/pdf/10.1152/physrev.00015.2005

Function of cGMP-Dependent Protein Kinases as Revealed by Gene Deletion

1 Nitric oxide has been described either as pronociceptive or antinociceptive In this investigation, using an electronic pressure-metre, the intradermal and the subcutaneous effects of prostaglandin E(2) (PGE(2)) and agents that mimic or inhibit the arginine/NO/cGMP pathway were compared 2 The hypernociceptive effect of the intradermal injection of PGE(2) (100 ng) was immediate, peaking within 15-30 min and returning to basal values in 45-60 min The subcutaneous injection of PGE(2) induced a hypernociception with a delayed peak (3 h) plateauing for 4-6 h 3 Intradermal administration of 3-morpholino-sydnonimine-hydrochloride (SIN-1) enhanced, while its subcutaneous administration inhibited, subcutaneous hypernociception induced by PGE(2) This inhibition was prevented by ODQ (8 micro g) but not by NG-monomethyl-L-arginine (L-NMMA) (50 micro g) 4 Intradermal but not subcutaneous administration of L-arginine (1-100 micro g), SIN-1 (1-100 micro g) and dibutyrylguanosine 3':5'-cyclic monophosphate (db cGMP) (01-100 micro g) induced an early (15-30 min) dose-dependent hypernociceptive effect Intradermal pretreatment with NG-monomethyl-L-arginine (L-NMMA; 50 micro g) inhibited the hypernociception induced by L-Arg (10 micro g), but not that induced by SIN-1 (10 micro g) or db cGMP (10 micro g) 5 Intradermal injection of ODQ (8 micro g) antagonized the hypernociception induced by L-arginine and SIN-1, but not that induced by db cGMP 6 Considering (a) the different time course of intradermal and subcutaneous PGE(2)-induced hypernociception, (b) the opposite nociceptive effect of intradermal and subcutaneous administration of SIN-1 (db cGMP) as well as the arginine/NO/cGMP pathway, the existence of different subsets of nociceptive primary sensory neurons in which the arginine/NO/cGMP pathway plays opposing roles is suggested This hypothesis would explain the apparent contradictory observations described in the literature

/pdf/opposite-nociceptive-effects-of-the-arginine-no-cgmp-pathway-9exmvxuaal.pdf

Opposite nociceptive effects of the arginine/NO/cGMP pathway stimulation in dermal and subcutaneous tissues

The present study investigated whether activation of presynaptic N-methyl-d-aspartate (NMDA) receptors in the spinal cord produces a retrograde nociceptor sensitization (hypernociception) to mechanical nonnoxious stimulus. By using an electronic version of the von Frey hair test (pressure meter), s.c. intraplantar administration of prostaglandin E2 (PGE2) (50–400 ng per paw) evoked a dose-related ipsilateral paw hypernociception. In contrast, intrathecal (i.t.) administration of NMDA (5–80 ng) and PGE2 (15–150 ng) evoked dose-related bilateral paw hypernociception. The s.c. intraplantar administration of dipyrone (80–320 μg per paw) or morphine (3 and 9 μg per paw), usually used to antagonize peripheral PGE2 (100 ng per paw), induced hypernociception and also antagonized the ipsilateral (without affecting the contralateral) paw hypernociception induced by i.t. injections of NMDA (40 ng) or PGE2 (50 ng). These doses of drugs did not modify the basal mechanical sensitivity of control paws. This result shows that intraspinal NMDA or PGE2 produces sensitization of the primary sensory neuron in response to mechanical stimulation. In a second series of experiments it was shown that the i.t. treatment with NaV1.8 (SNS/PN3) sodium channel antisense oligodeoxynucleotides, but not mismatch oligodeoxynucleotides, decreased the mRNA expression of sodium tetrodotoxin-resistant channels on the dorsal root ganglia and abolished the mechanical hypernociception induced by i.t. administration of NMDA. Thus, our results support the suggestion that glutamate release in the spinal cord during inflammation causes retrograde hypernociception of nociceptors associated with sodium tetrodotoxin-resistant channels in primary nociceptive sensory neurons.

https://www.pnas.org/content/pnas/100/5/2923.full.pdf

G.G. Vivancos

Papers

An electronic pressure-meter nociception paw test for mice

Opposite nociceptive effects of the arginine/NO/cGMP pathway stimulation in dermal and subcutaneous tissues

Activation of presynaptic NMDA receptors coupled to NaV1.8-resistant sodium channel C-fibers causes retrograde mechanical nociceptor sensitization