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V Chapman

Publications and source records attributed to V Chapman.

At least 19 recordsLinked to original sources
PubMed1998

Electrophysiological characterization of spinal neuronal response properties in anaesthetized rats after ligation of spinal nerves L5-L6.

1. Despite a number of models of nerve injury, few studies have examined how peripheral nerve injury influences spinal somatosensory processing. 2. Ligation of two (L5-L6) of the three spinal nerves that form the sciatic nerve produces a partial denervation of the hindlimb. Following ligation, rats exhibited withdrawal responses to normally innocuous punctate mechanical and cooling stimuli (acetone) applied to the lesioned hindpaw. Such mechanical and cooling allodynia was not observed in sham-operated rats. 3. A significantly greater proportion of spinal neurones of ligated rats exhibited spontaneous activity at post-operative (PO) days 7-10 (P = 0.03) and 14-17 (P = 0.0001), compared with sham controls. The frequency of the spontaneous activity was significantly higher than that of the sham controls (P = 0.03 and P = 0.02 for days 7-10 and days 14-17, respectively). 4. At the earlier PO period, significantly (P = 0.02) more neurones of spinal nerve-ligated (SNL) rats responded to brush compared with the sham controls; at the later PO period the proportion of neurones of SNL rats responsive to prod was significantly (P = 0.007) reduced compared with the sham controls. The magnitude of the evoked neuronal response of SNL rats at PO days 7-10 was comparable to that of the sham controls. The magnitudes of brush- and prod-evoked neuronal responses of SNL rats were significantly smaller (P = 0.05 and P = 0.002, respectively) than the sham controls at PO days 14-17. In addition, neuronal responses of SNL rats to mechanical punctate stimuli and the C fibre-evoked neuronal responses were significantly reduced at the later PO period, compared with sham controls. Abeta-fibre-induced wind-up was not observed under any conditions. 5. These complex changes in neuronal responses are both time and modality dependent. The plasticity of some of the neuronal and behavioural responses following nerve injury was difficult to reconcile. We suggest that an interplay between pathological peripheral and central mechanisms may account for some of the changes that could contribute to allodynia and hyperalgesia.

Acetone↗
PubMed1998

A case report of Usher's syndrome and anorexia nervosa.

OBJECTIVE: This report describes the rare combination of anorexia nervosa, deafness, and visual impairment with a particular emphasis on management issues. To the author's knowledge, this is the first report of an eating disorder in a patient who is deaf with a visual impairment. DISCUSSION: It describes the history of such a patient and the difficulties encountered in her treatment.

Adult↗
PubMed1998

Effects of systemic carbamazepine and gabapentin on spinal neuronal responses in spinal nerve ligated rats.

There are few pharmacological studies of central neuronal measures in animal models of neuropathic pain. In the present study we have compared the effects of two anticonvulsants, carbamazepine and gabapentin, on spinal neuronal responses of nerve injured rats (selective ligation of spinal nerves L5 and L6, SNL) and sham-operated rats. The development and maintenance of cooling and mechanical allodynia of the lesioned hindlimb of SNL rats was followed with behavioural indices. The contralateral hindlimb of SNL rats and the ipsilateral hindlimb of sham-operated rats did not develop allodynia. Electrophysiological studies of SNL rats were then performed at two post-operative (PO) time points (PO days 7-10 and PO days 14-17). Spinal neurones of SNL rats, but not sham-operated rats, exhibited spontaneous activity at both PO days 7-10 and 14-17 (1 +/- 0.4 and 3 +/- 1 Hz, respectively). Paradoxically, the magnitude of electrical (C-fibre) and natural (mechanical and thermal) evoked neuronal responses of SNL rats at PO days 14-17 were smaller than the evoked neuronal responses of SNL rats at PO days 7-10 and sham-operated rats. The electrical evoked A-fibre responses of neurones were comparable for the three groups of rats. Both subcutaneous carbamazepine (0.5-22.5 mg/kg) and gabapentin (10-100 mg/kg) significantly reduced the spontaneous activity of spinal neurones of SNL rats at both PO time points. Carbamazepine had inhibitory effects on electrical C- and A-fibre and mechanical punctate (9 and 50 g) evoked neuronal responses of SNL rats which were significantly different to the lack of effect of carbamazepine on these measures in sham-operated rats. Gabapentin had comparable effects as carbamazepine on the electrical C-and A-fibre and mechanical punctate (9 and 50 g) evoked neuronal responses of SNL rats. In contrast to carbamazepine, gabapentin also reduced evoked neuronal responses of sham-operated rats and there was no difference between the effects of gabapentin in SNL and sham-operated rats. Robust behavioural changes in the SNL model of neuropathy are paralleled by a temporal increase in spontaneous activity and a paradoxical decrease in evoked spinal neuronal responses. The peripheral nerve dysfunction reveals an effect of carbamazepine which is maintained throughout the observation period, validating this experimental approach. Gabapentin, a novel treatment for neuropathic pain states, also reduced neuronal responses, but the actions of the drug were not dependent on nerve injury. Further studies at the spinal level may shed light on the physiology and pharmacology of the aberrant processes associated with neuropathic pain.

Acetates↗
PubMed1998

UP 202-56, an adenosine analogue, selectively acts via A1 receptors to significantly decrease noxiously-evoked spinal c-Fos protein expression.

The effects of oral administration of UP 202-56, an adenosine analogue, were assessed on carrageenan-induced spinal c-Fos protein expression and peripheral oedema. Three hours after intraplantar injection of carrageenan (6 mg/150 microl of saline), in awake rats, numerous c-Fos-like immunoreactive (c-Fos-LI) neurons in the dorsal horn of L4-L5 lumbar segments of the spinal cord (191 +/- 8; 184 +/- 10; 205 +/- 7 c-Fos-LI neurons per 40 microm section, for carrageenan controls in three experimental series performed in this study, respectively) and an extensive peripheral oedema were observed. Oral UP 202-56 (10, 30 or 50 mg/kg) dose-dependently reduced the number of carrageenan-induced c-Fos-LI neurons (r = 0.931. P < 0.0001), with the highest dose of UP 202-56 producing 72 +/- 4% reduction of the total number of carrageenan-induced spinal c-Fos-LI neurons, and 12 +/- 3% and 33 +/- 6% of reduction of control carrageenan oedema at paw and ankle levels, respectively. DPCPX (1 mg/kg i.p.), a selective adenosine A1 receptor antagonist, which injected alone had no effect on carrageenan-induced spinal c-Fos expression and peripheral oedema, blocked the effects of UP 202-56 (30 mg/kg p.o.) on the number of carrageenan-induced c-Fos-LI neurons. In addition, DPCPX did not modify the effects of UP 202-56 on carrageenan-induced peripheral oedema. DMPX (1 mg/kg i.p.), a somewhat selective adenosine A2 receptor antagonist, which injected alone had no significant effect on carrageenan-induced spinal c-Fos protein expression and peripheral oedema, did not influence the effects of UP 202-56 (30 mg/kg p.o.) on both carrageenan-induced spinal c-Fos expression and peripheral oedema. Our results demonstrate that UP 202-56 dose-dependently reduced the spinal c-Fos protein expression in carrageenan model of inflammatory pain. The ability of DPCPX to block the effect of UP 202-56, in contrast to the lack of effect of DMPX, increased evidence for a predominant role of adenosine A1 receptors activation in the mechanism of action of UP 202-56. These results increase evidence for a role of adenosine in the modulation of nociceptive transmission and support the antinociceptive action of adenosine analogues, such as UP 202-56, in inflammatory pain processes.

Adenosine↗
PubMed1998

The mouse Mid1 gene: implications for the pathogenesis of Opitz syndrome and the evolution of the mammalian pseudoautosomal region.

We have recently reported isolation of the gene responsible for X-linked Opitz G/BBB syndrome, a defect of midline development. MID1 is located on the distal short arm of the human X chromosome (Xp22. 3) and encodes a novel member of the B box family of zinc finger proteins. We have now cloned the murine homolog of MID1 and performed preliminary expression studies during development. Mid1 expression in undifferentiated cells in the central nervous, gastrointestinal and urogenital systems suggests that abnormal cell proliferation may underlie the defect in midline development characteristic of Opitz syndrome. We have also found that Mid1 is located within the mouse pseudoautosomal region (PAR) in Mus musculus , while it seems to be X-specific in Mus spretus. Therefore, Mid1 is likely to be a recent acquisition of the M. musculus PAR. Genetic and FISH analyses also demonstrated a high frequency of unequal crossovers in the murine PAR, creating spontaneous deletion/duplication events involving Mid1. These data provide evidence for the first time that genetic instability of the PAR may affect functionally important genes. In addition, we show that MID1 is the first example of a gene subject to X-inactivation in man while escaping it in mouse. These data contribute to a better understanding of the molecular content and evolution of the rodent PAR.

Abnormalities, Multiple↗
PubMed1997

Inflammation reveals inhibition of noxious responses of rat spinal neurones by carbamazepine.

The effect of subcutaneously administered carbamazepine, a sodium channel blocker, on the electrically evoked C-fibre (noxious) vs A beta-fibre (innocuous) responses of dorsal horn neurones in non-inflamed and inflamed rats (3 h after plantar injection of carrageenan) was studied. Carbamazepine (0.5-5 mg/kg) significantly reduced the noxious evoked responses of the neurones under inflammatory, but not non-inflamed, conditions. The innocuous evoked responses of the neurones were not sensitive to carbamazepine under any conditions and administration of the vehicle alone did not influence any evoked response of these neurones. We propose that there are changes in the type, or proportion of, sodium channels underlying the transmission of noxious messages following peripheral inflammation which become sensitive to carbamazepine.

Analysis of Variance↗
PubMed1997

The contribution of peripheral bradykinin B2 receptors to carrageenan-evoked oedema and spinal c-Fos expression in rats.

Intraplantar co-injection of HOE140 (D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]bradykinin), a selective bradykinin B2 receptor antagonist (0.1, 1 and 10 micrograms), with carrageenan dose-dependently (r = 0.66, P < 0.01) reduced the carrageenan-evoked total number of c-Fos protein-like immunoreactive (c-Fos-LI) neurones (23 +/- 5%, 35 +/- 6% and 50 +/- 5% reduction; P < 0.01, P < 0.001 and P < 0.001, respectively). These reducing effects were dose-dependent for the number of c-Fos-LI neurones in both superficial (r = 0.70, P < 0.01) and deep (r = 0.53, P < 0.05) laminae. Intraplantar co-injection of HOE140 (0.1, 1 and 10 micrograms) with carrageenan significantly reduced the carrageenan-evoked paw (25 +/- 7%, 41 +/- 6% and 41 +/- 3% reduction; P < 0.001 for all) and ankle (46 +/- 6%, 61 +/- 5% and 61 +/- 5% reduction; P < 0.001 for all) oedema. Our results provide further evidence for the involvement of peripheral bradykinin B2 receptors in carrageenan-induced inflammatory nociceptive transmission.

Animals↗
PubMed1997

Distinct electrophysiological effects of two spinally administered membrane stabilising drugs, bupivacaine and lamotrigine.

A selective blockade of the relay of messages by C-fibres into the spinal cord is a logical approach to the reduction of nociceptive transmission. Here we compared the effect of two distinctly different sodium channel blockers, the local anaesthetic bupivacaine and the novel anti-epileptic lamotrigine, on the responses of dorsal horn neurones following noxious and innocuous stimulation. Dorsal horn neuronal responses following acute repetitive C-fibre electrical stimulation (three times the C-fibre threshold at 0.5 Hz) were recorded in intact halothane anaesthetised rats. Wind up, an enhanced C-fibre evoked response of dorsal horn neurones, and an associated post discharge were observed following repetitive stimulation. The effects of spinally administered bupivacaine and lamotrigine on the dorsal horn neuronal responses were investigated. Spinal bupivacaine (25-1000 microg/50 microl) dose dependently reduced the C-fibre evoked responses (r2 = 0.5, P < 0.0003), wind up (r2 = 0.4, P < 0.002) and the post discharge (r2 = 0.34, P < 0.005) of these neurones. The effects of bupivacaine were long lasting, up to 120 min post-administration. The Abeta-fibre evoked responses were not dose-dependently reduced by bupivacaine. Spinal lamotrigine (50-1000 microg/50 microl) did not significantly reduce the C- or Abeta-fibre evoked responses. In contrast there was a tendency for wind up and post discharge to be facilitated by lamotrigine. Although both bupivacaine and lamotrigine are sodium channel blockers, the effects of the two drugs on the C-fibre and Abeta-fibre evoked responses were completely different. Bupivacaine reduced C-fibre evoked responses whereas lamotrigine had a tendency to facilitate responses. The profile of sodium channel blockers would appear highly diverse and the status of lamotrigine as a potential analgesic remains unclear.

Anesthetics, Local↗
PubMed1997

The pharmacology of excitatory and inhibitory amino acid-mediated events in the transmission and modulation of pain in the spinal cord.

1. The aim of this review is to consider the relative roles of inhibitory and excitatory amino acid receptor-mediated events in the processes leading to pain transmission in the spinal cord. 2. Emphasis will be on the roles of the inhibitory and excitatory amino acids, GABA and glutamate, and how the relative balance between activity in these systems appears to determine the level of pain transmission. 3. The N-methyl-D-aspartate (NMDA) receptor for glutamate has been implicated in the generation and maintenance of central (spinal) states of hypersensitivity. It has been shown that activation of this receptor underlies wind-up, whereby the level of transmission of noxious messages is potentiated. Antagonists at this receptor-channel complex prevent or block enhanced (hyperalgesic) pain states induced by tissue damage, inflammation, nerve damage and ischemia. 4. Information concerning amplification systems in the spinal cord, such as the NMDA receptor, is a step toward understanding why and how a painful response is not always matched to the stimulus. Such events have parallels with other plastic events such as long-term potentiation (LTP) in the hippocampus. 5. However, the roles of inhibitory transmitter systems can also change insofar as opioid, adenosine and GABA transmission in the spinal cord can vary in different pain states. 6. Changes in GABA systems have been well-documented and discussion will center on whether this has clinical implications. 7. In addition to behavioral and electrophysiological approaches to the pharmacology of pain the current status of the use of markers of early onset genes such as c-fos, as monitors of activity, will be discussed. 8. Hyperalgesia would appear to be balanced by inhibitions during inflammatory conditions but not in neuropathic states, pains due to nerve damage. In the latter case, events reminiscent of LTP may predominate, whereas they are held in check by inhibitions under conditions of inflammation.

Animals↗
PubMed1997

Distinct inhibitory effects of spinal endomorphin-1 and endomorphin-2 on evoked dorsal horn neuronal responses in the rat.

Intrathecal endomorphin-1 and endomorphin-2 (0.25-50 micrograms) dose-relatedly reduced all components of electrical evoked C-fibre responses of spinal neurones. These effects were partially reversed by naloxone. Endomorphin-1, but not endomorphin-2, dose-relatedly reduced the A beta-fibre evoked responses. Peak inhibitory effects of endomorphin-1 and -2 were at 15-20 min post-administration. Thus spinal endomorphin-2 had selective effects on noxious responses, whereas endomorphin-1 was non-selective.

Analgesics, Opioid↗
PubMed1996

A new region of conservation is defined between human and mouse X chromosomes.

Comparative mapping of the X chromosome in eutherian mammals has revealed distinct regions of conservation as well as evolutionary rearrangements between human and mouse. Recently, we and others mapped the murine homologue of CLCN4 (Chloride channel 4) to band F4 of the X chromosome in Mus spretus but to chromosome 7 in laboratory strains. We now report the mapping of the murine homologues of APXL (Apical protein Xenopus laevis-like) and OA1 (Ocular albinism type I), two genes that are located on the human X chromosome at band p22. 3 and in close proximity to CLCN4. Interestingly, Oa1 and Apxl map to bands F2-F3 in both M. spretus and the laboratory strain C57BL/6J, defining a new rearrangement between human and mouse X chromosomes.

Albinism, Ocular↗
PubMed1996

Interactions between NMDA- and prostaglandin receptor-mediated events in a model of inflammatory nociception.

Preadministered niflumic acid, a nonsteroidal anti-inflammatory drug (1, 3 and 9 mg/kg i.v.), dose-relatedly reduced carrageenan-evoked spinal c-Fos expression and the peripheral ankle oedema, with the highest dose reducing in parallel both parameters (55 +/- 3% reduction of carrageenan c-Fos expression, 57 +/- 13% reduction of carrageenan-evoked ankle oedema, respectively, P < 0.001 for both). Co-administration of low doses of niflumic acid and (+)-HA966, a low-efficacy partial agonist at the glycine site of the NMDA receptor (1 mg/kg i.v. + 2.5 mg/kg s.c., respectively) significantly reduced spinal c-Fos expression, this effect was significantly different from the lack of effect of niflumic acid alone or (+)-HA966 alone on spinal c-Fos expression (P < 0.01 for both drugs). Co-administered niflumic acid and (+)-HA966 did not influence the peripheral carrageenan-evoked oedema. Spinal interactions between prostaglandin-and NMDA receptor-mediated events during inflammatory nociceptive transmission are discussed.

Animals↗
PubMed1996

Selective cyclooxygenase-2 inhibition reduces carrageenan oedema and associated spinal c-Fos expression in the rat.

Pre-administered NS-398 (0.1, 1 and 10 mg/kg p.o.), a selective cyclooxygenase-2 inhibitor without gastro-intestinal side-effects, dose-dependently reduced carrageenan evoked spinal c-Fos expression (16 +/- 4%, 32 +/- 3% and 56 +/- 5% reduction, respectively) at 3 h after intraplantar carrageenan. The effects of NS-398 on carrageenan induced peripheral oedema and spinal c-Fos expression were correlated, thus demonstrating the beneficial relief of inflammatory pain.

Animals↗
PubMed1996

The contribution of GABAB receptor-mediated events to inflammatory pain processing: carrageenan oedema and associated spinal c-Fos expression in the rat.

In this pharmacological study we have assessed the effect of baclofen, a selective GABAB receptor agonist, on spinal expression of the immediate early gene c-Fos and the peripheral oedema evoked by a prolonged peripheral inflammation due to intraplantar carrageenan. Baclofen was administered intravenously 30 min before intraplantar injection of carrageenan in freely moving rats. Three hours after carrageenan the number of spinal c-Fos protein-like immunoreactive neurons and peripheral (ankle and paw) oedema were assessed. For the two series of experiments the total number of control carrageenan-evoked c-Fos protein-like immunoreactive neurons in segments L4-L5 of the spinal cord was 176 +/- 6 and 177 +/- 9 c-Fos protein-like immunoreactive neurons per section, for carrageenan control with intravenous and intraplantar saline, respectively. c-Fos protein-like immunoreactive neurons were predominantly located in laminae I-II and V-VI of the dorsal horn of the spinal cord in carrageenan controls receiving intravenous (68 +/- 3 and 69 +/- 2 c-Fos protein-like immunoreactive neurons, respectively) and intraplantar (62 +/- 4 and 71 +/- 5 c-Fos protein-like immunoreactive neurons, respectively) saline. Pre-administered systemic baclofen (0.05, 1.5 and 3 mg/kg i.v.) dose dependently reduced the total number of c-Fos protein-like immunoreactive neurons (81 +/- 3, 66 +/- 4 and 49 +/- 4% of control total number of c-Fos protein-like immunoreactive neurons, respectively), with strongest effects on the number of deep (74 +/- 3, 60 +/- 3 and 43 +/- 4% of control, respectively) as compared with superficial (90 +/- 4, 77 +/- 5 and 59 +/- 5% of control, respectively) c-Fos protein-like immunoreactive neurons. The effects of systemic baclofen on the carrageenan-induced spinal c-Fos expression and both the paw and ankle oedema were positively correlated (r = 0.479, P < 0.05 and r = 0.733, P < 0.001, respectively). Intraplantar baclofen (50 and 100 micrograms in 50 microliters of saline), simultaneously injected with intraplantar carrageenan, did not significantly influence carrageenan-evoked spinal c-Fos expression or ankle oedema. Despite the fact that the highest dose of intraplantar baclofen significantly reduced paw oedema (23 +/- 3% reduction of control paw oedema), our results are clearly in favour of a spinal site of action of systemic baclofen.

Animals↗
PubMed1996

Concomitant administration of morphine and an N-methyl-D-aspartate receptor antagonist profoundly reduces inflammatory evoked spinal c-Fos expression.

BACKGROUND: After intraplantar injection of carrageenin, peripheral inflammation and spinal c-Fos expression are extensive, with the latter being sensitive to both large doses of morphine or N-methyl-D-aspartate receptor antagonism. The authors investigated the effects of coadministered morphine and (+)-HA966, a functional antagonist at the glycine site of the N-methyl-D-aspartate receptor, on the two parameters. METHODS: The effects of morphine, (+)-HA966 and coadministration of morphine and (+)-HA966 on spinal c-Fos expression in segments L4-L5 of the spinal cord and peripheral edema, induced at 1.5 h and 3 h after intraplantar carrageenin (6 mg/150 microliters) were studied. RESULTS: Previous coadministration of 0.3 mg/kg systemic morphine and 2.5 mg/kg subcutaneous (+)-HA966 significantly reduced c-Fos expression induced 1.5 h, but not 3 h, after carrageenin administration. However, coadministration of a larger dose of morphine (3 mg/kg) with (+)-HA966 (2.5 mg/kg) reduced c-Fos expression at 3 h after carrageenin administration, in a partially naloxone-reversible manner. CONCLUSIONS: Concurrent mu-opioid receptor activation and N-methyl-D-aspartate receptor antagonism reduces nociceptive transmission at the level of the spinal cord, as shown by the reduction of carrageenin-evoked c-Fos expression.

Analgesics, Opioid↗
PubMed1996

Inhibitory action of nociceptin on spinal dorsal horn neurones of the rat, in vivo.

Intrathecally administered nociceptin (5, 50, 225 micrograms) dose-relatedly inhibited the C-fibre evoked wind-up and post-discharge of dorsal horn neurones, but not the baseline C-fibre evoked responses. Spinal naloxone 50 micrograms, but not 10 micrograms, reversed the effects of nociceptin. Thus the antinociceptive role of nociceptin in the spinal cord differs from that of classical opioids.

Animals↗
PubMed1996

Physiological contributions of neurokinin 1 receptor activation, and interactions with NMDA receptors, to inflammatory-evoked spinal c-Fos expression.

1. Intraplantar injection of formalin (5%, 100 microliters in saline) was associated with a high level of spinal c-Fos immunoreactivity and a peripheral paw and ankle edema, as assessed at 3 h after formalin administration. For the two experimental series, the control number of formalin-evoked Fos-like immunoreactive (Fos-LI) neurons were 174 +/- 6 and 193 +/- 18 (means +/- SE) Fos-LI neurons per 40-microns section of the lumbar segment L4-L5 of the rat spinal cord. For both series of experiments, Fos-LI neurons were located predominantly in the superficial (I-II; 40 and 44% of the total number of Fos-LI neurons for the two experimental series) and deep (V-VI; 37 and 40% of the total number of Fos-LI neurons for the two experimental series) laminae of the dorsal horn of the spinal cord. The small number of remaining Fos-LI neurons were located in the nucleus proprius (laminae III-IV) and the ventral horn. 2. Prior intravenous administration of RP67580 (0.05, 0.5, and 1.5 mg/kg), a selective neurokinin 1 (NK1) receptor antagonist, dose-relatedly reduced the total number of formalin evoked Fos-LI neurons (88 +/- 5%, 80 +/- 4%, P < 0.01 and 64 +/- 4%, P < 0.0001, of the control number of formalin-evoked Fos-LI neurons). Laminar analysis of the regional effect of RP67580 on formalin-evoked Fos-LI neurons illustrated that the number of superficial and deep laminae Fos-LI neurons were attenuated to a similar extent by RP67580. 3. Prior intravenous administration of RP68651 (1.5 mg/kg), the inactive isomer of RP67580, produced only a small reduction in the total number of formalin-evoked Fos-LI neurons (84 +/- 5% of the control number of formalin-evoked Fos-LI neurons (P < 0.05). The effect of RP68651 on the number of formalin-evoked Fos-LI neurons was significantly smaller (P < 0.01) than the effect of the equivalent concentration of RP67580, the active isomer. 4. Prior coadministration of intravenous RP67580 (0.5 mg/kg) and subcutaneous (+)-HA966 (2.5 mg/kg), an antagonist at the glycine site of the N-methyl-D-aspartate (NMDA) receptor, significantly reduced the number of formalin-evoked Fos-LI neurons (64 +/- 4% of the control number of formalin-evoked Fos-LI neurons, P < 0.01). The attenuating effect of coadministered RP67580 and (+)-HA966 was significantly greater than the effect of RP67580 alone (P < 0.01) and the effect of (+)-HA966 alone (P < 0.05). Laminar analysis illustrated that coadministered RP67580 and (+)-HA966 reduced the number of formalin-evoked Fos-LI neurons in the superficial and deep laminae to a similar extent. 5. Intraplantar injection of formalin was associated with a peripheral paw (0.92 +/- 0.02 cm) and ankle (0.92 +/- 0.02 cm) edema, as compared with the paw (0.46 +/- 0.02 cm) and ankle (0.67 +/- 0.14 cm) diameters of saline-stimulated rats. Neither prior administration of intravenous RP67580 (0.05, 0.5, and 1.5 mg/kg) or RP68651 (1.5 mg/kg) or prior coadministration of RP67580) (0.5 mg/kg) and (+)-HA966 (2.5 mg/kg) influenced the extent of the paw or ankle-edema at 3 h after intraplantar injection of formalin. 6. Our results illustrate that NK1-receptor activation contributes to inflammatory-evoked spinal c-Fos expression and thus supports the current contention that NK1-receptor activation, and by inference SP, plays a role in spinal nociceptive processing. The second part of our study suggests that the previously reported NK1/NMDA-receptor interactions contribute to formalin-evoked spinal c-Fos expression and consequently may contribute to the longer term spinal neuroplasticity associated with inflammatory nociceptive processing.

Analgesics↗