[Investigate of the etiology and prevention status of liver cirrhosis].

Objective: To investigate the etiology, prevention and treatment status, and their corresponding regional differences of the patients with liver cirrhosis in China, in order to provide scientific basis for the development of diagnosis and control strategies in China. Methods: Clinical data of patients diagnosed with liver cirrhosis for the first time through January 1, 2018 to December 31, 2020 from 50 hospitals in seven different regions of China were collected and analyzed retrospectively, and the difference of etiology, treatment, and their differences in various regions were analyzed. Results: A total of 11 861 cases with liver cirrhosis were included in the study. Thereinto, 5 093 cases (42.94%) were diagnosed as compensated cirrhosis, and 6 768 cases (57.06%) had decompensated cirrhosis. Notably, 8 439 cases (71.15%) were determined as chronic hepatitis B-caused cirrhosis, 1 337 cases (11.27%) were alcoholic liver disease, 963 cases (8.12%) were chronic hepatitis C, 698 cases (5.88%) were autoimmune liver disease, 367 cases (3.09%) were schistosomiasis, 177 cases (1.49%) were nonalcoholic fatty liver, and 743 cases (6.26%) of other types of liver disease. There were significant differences in the incidence of chronic hepatitis B, chronic hepatitis C, alcoholic liver disease, fatty liver, schistosomiasis liver disease, and autoimmune liver disease among the seven regions (P<0.001). Only 1 139 cases (9.60%) underwent endoscopic therapy, thereinto, 718 cases (6.05%) underwent surgical therapy, and 456 cases (3.84%) underwent interventional therapy treatment. In patients with compensated liver cirrhosis, 60 cases (0.51%) underwent non-selective ß receptor blockers(NSBB), including 59 cases (0.50%) underwent propranolol and 1 case (0.01%) underwent carvedilol treatment. In patients with decompensated liver cirrhosis, 310 cases (2.61%) underwent NSBB treatment, including 303 cases (2.55%) underwent propranolol treatment and 7 cases (0.06%) underwent carvedilol treatment. Interestingly, there were significant differences in receiving endoscopic therapy, interventional therapy, NSBB therapy, splenectomy and other surgical treatments among the seven regions (P<0.001). Conclusion: Currently, chronic hepatitis B is the main cause (71.15%) of liver cirrhosis in several regions of China, and alcoholic liver disease has become the second cause (11.27%) of liver cirrhosis in China. The three-level prevention and control of cirrhosis in China should be further strengthened.

Analysis of synonymous codon usage in FAD7 genes from different plant species.

In this study, the codon bias of the FAD7 genes among 10 different plant species was analyzed to identify general patterns of codon usage in the FAD7 genes. Our results showed that U-ended or A-ended codons were preferentially used in FAD7 for dicots, whereas G-ended or C-ended codons were preferentially used in FAD7 for monocots. An ENC-plot showed that some other factors may influence the codon usage of FAD7, except mutation bias in plant species. A correlation analysis between the codon adaptation index and GC or GC3s contents demonstrated that the codon usage bias of the FAD7 gene in plant species could be influenced by the gene expression level. The cluster analysis of relative synonymous codon usage values and phylogenetic trees of protein sequences for FAD7 genes confirm that the codon preference of FAD7 is influenced by genetic relationships. Moreover, Arabidopsis thaliana and Nicotiana tabacum were predicted to be the most appropriate expression hosts for the FAD7 genes from dicots, and Zea mays may be suitable for the expression of the FAD7 genes from monocots. Our results provide useful insights into the evolutionary relationships of plant species.

Novel compounds selectively enhance delta subunit containing GABA A receptors and increase tonic currents in thalamus.

Inhibition in the brain is dominated by the neurotransmitter gamma-aminobutyric acid (GABA); operating through GABA(A) receptors. This form of neural inhibition was presumed to be mediated by synaptic receptors, however recent evidence has highlighted a previously unappreciated role for extrasynaptic GABA(A) receptors in controlling neuronal activity. Synaptic and extrasynaptic GABA(A) receptors exhibit distinct pharmacological and biophysical properties that differentially influence brain physiology and behavior. Here we used a fluorescence-based assay and cell lines expressing recombinant GABA(A) receptors to identify a novel series of benzamide compounds that selectively enhance, or activate alpha4beta3delta GABA(A) receptors (cf. alpha4beta3gamma2 and alpha1beta3gamma2). Utilising electrophysiological methods, we illustrate that one of these compounds, 4-chloro-N-[6,8-dibromo-2-(2-thienyl)imidazo[1,2-a]pyridine-3-yl benzamide (DS1) potently (low nM) enhances GABA-evoked currents mediated by alpha4beta3delta receptors. At similar concentrations DS1 directly activates this receptor and is the most potent known agonist of alpha4beta3delta receptors. 4-chloro-N-[2-(2-thienyl)imidazo[1,2-a]pyridine-3-yl benzamide (DS2) selectively potentiated GABA responses mediated by alpha4beta3delta receptors, but was not an agonist. Recent studies have revealed a tonic form of inhibition in thalamus mediated by the alpha4beta2delta extrasynaptic GABA(A) receptors that may contribute to the regulation of thalamocortical rhythmic activity associated with sleep, wakefulness, vigilance and seizure disorders. In mouse thalamic relay cells DS2 enhanced the tonic current mediated by alpha4beta2delta receptors with no effect on their synaptic GABA(A) receptors. Similarly, in mouse cerebellar granule cells DS2 potentiated the tonic current mediated by alpha6betadelta receptors. DS2 is the first selective positive allosteric modulator of delta-GABA(A) receptors and such compounds potentially offer novel therapeutic opportunities as analgesics and in the treatment of sleep disorders. Furthermore, these drugs may be valuable in elucidating the physiological and pathophysiological roles played by these extrasynaptic GABA(A) receptors.

The JAK3 inhibitor WHI-P154 prevents PDGF-evoked process outgrowth in human neural precursor cells.

The prospect of manipulating endogenous neural stem cells to replace damaged tissue and correct functional deficits offers a novel mechanism for treating a variety of CNS disorders. The aim of this study was to investigate pathways controlling neurite outgrowth in human neural precursor cells, in particular in response to platelet-derived growth factor (PDGF). PDGF-AA, -AB and -BB were found to initiate calcium signalling and produce robust increases in neurite outgrowth. PDGF-induced outgrowth of Tuj1-positive precursors was abolished by the addition of EGTA, suggesting that calcium entry is a critical part of the signalling pathway. Wortmannin and PD098059 failed to inhibit PDGF-induced outgrowth. Clostridium Toxin B increased the amount of PDGF-induced neurite branching but had no effect on basal levels. In contrast, WHI-P154, an inhibitor of Janus protein tyrosine kinase (JAK3), Hck and Syk, prevented PDGF-induced neurite outgrowth. PDGF activates multiple signalling pathways with considerable potential for cross-talk. This study has highlighted the complexity of the pathways leading to neurite outgrowth in human neural precursors, and provided initial evidence to suggest that calcium entry is critical in producing the morphological changes observed.

5-HT1B-receptors and vascular reactivity in human isolated blood vessels: assessment of the potential craniovascular selectivity of sumatriptan.

AIMS: 5-HT1B-receptor mediated vasoconstriction of cranial arteries is a potential mechanism by which 5-HT1B/1D-receptor agonists such as sumatriptan produce their antimigraine effects. 5-HT1B-receptors exist in other blood vessels which may give rise to unwanted vascular effects. Therefore we examined the distribution of 5-HT1B-receptor immunoreactivity (i.r.) in human blood vessels (including target and nontarget vessels) and confirmed the functionality of this receptor protein, by comparing the vasoconstrictor effects of sumatriptan and 5-HT (the endogenous ligand) in isolated vessels. METHODS: Blood vessels (middle meningeal, pial, temporal and uterine arteries and saphenous veins) were obtained from surgical patients (with consent). Sections of the vessels were prepared for routine immunohistochemical studies using specific 5-HT1B- and 5-HT1D-receptor antibodies. For functional studies, ring segments of the vessels were mounted in organ baths for isometric tension recording. RESULTS: 5-HT1B-receptor i.r. was detected on the smooth muscle layer in middle meningeal, pial and uterine arteries and in saphenous vein and sumatriptan produced contractions in these vessels with potency values (mean pEC50) of 7.00, 7.08, 6.44 and 6.61, respectively, the magnitude of contraction was greatest in the cranial arteries with Emax values of 100.7, 60.3, 23.0 and 35.9%, respectively (expressed as a percentage of the reference agonist 45 mm KCl). 5-HT1B-receptor i.r. was not detected in temporal artery and sumatriptan had no effect in this artery. 5-HT1D-receptor i.r. was not detected in any of the vessels studied. CONCLUSIONS: Sumatriptan can evoke vasoconstriction in antimigraine target vessels and also in nontarget vessels through an action at 5-HT1B-rcceptors. Sumatriptan acts preferentially to cause contraction in human cranial arteries compared with the other blood vessels we examined and this effect is likely to be shared by other drugs of this class.

Vanilloid receptor homologue, VRL1, is expressed by both A- and C-fiber sensory neurons.

The capsaicin receptor (VR1) homologue, VRL1, is thought to be responsible for transducing high-threshold heat responses in Adelta-fiber neurons. In the present study, the expression of VRL1 by A- or C-fiber sensory neurons in rats was investigated by using a VRL1 and 200 kDa neurofilament (NF200, an A-fiber marker) double immunohistochemical staining method. Approximately 46% of VRL-positive neurons were NF200 positive. Though double-labeled neurons tended to be medium to large, many VRL1 single-labeled neurons were large. Dense VRL1 immunoreactivity was also found in laminae I and II of the spinal dorsal horn, where nociceptive Adelta- and C-fibers normally terminate. These results suggest that both C-fiber and Adelta-fiber primary sensory neurons express VRL1, and VRL1 may play an important role in nociception.

The expression of bradykinin B(1) receptors on primary sensory neurones that give rise to small caliber sciatic nerve fibres in rats.

The bradykinin B(1) receptor has been considered as an important mediator for inflammatory pain. In the present study, we have investigated the fibre types of sciatic nerve primary sensory neurones that express B(1) receptors by retrograde tracing in combination with immunohistochemical staining, or double-immunohistochemical staining. Approximately 12% of the A-fibre dorsal root ganglion neurones, retrogradely labelled from an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated cholera toxin B subunit, were B(1) receptor-immunoreactive. Over 70% of the small diameter dorsal root ganglion neurones, retrogradely labelled from an intra-sciatic nerve injection of tetramethylrhodamine isothiocyanate-conjugated wheat germ agglutinin, were B(1) receptor-immunoreactive. Over 50% of the (predominantly non-peptidergic) C-fibre dorsal root ganglion neurones, retrogradely labelled from an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated Bandeiraea simplicifolia isolectin B4, were B(1) receptor-immunoreactive. When calcitonin gene-related peptide, which is contained mainly in small caliber C- and A(delta)-fibre primary afferents, and B(1) receptors were stained with a double-immunofluorescent method, over 80% of the calcitonin gene-related peptide-positive dorsal root ganglion neurones were B(1) receptor-immunoreactive. From these results we suggest that B(1) receptors are predominantly expressed by small diameter primary afferent neurones that give rise to sciatic nerve fibres, which include both peptidergic and non-peptidergic C-fibres and A(delta)-fibres. Since peripheral nociceptive information is primarily transmitted by C- and A(delta)-fibres, B(1) receptors may be involved in the modulation of nociceptive transduction or transmission.

Basal expression of bradykinin B(1) receptor in the spinal cord in humans and rats.

The bradykinin B(1) receptor has been considered as a receptor induced by tissue injury and inflammation mainly in the peripheral tissues. In the present study, we have investigated whether there is a basal expression in the spinal cord by both reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical staining methods. Southern blotting of the DNA reverse-transcribed from human and rat spinal cord mRNA and amplified by polymerase chain reaction (PCR) showed a substantial basal B(1) receptor expression in both human and rat spinal cord. Immunohistochemical staining demonstrated B(1)-positive neurons in the spinal cord dorsal horn, suggesting that the B(1) receptor is constitutively expressed by spinal neurons.

A-fibres sprouting from lamina I into lamina II of spinal dorsal horn after peripheral nerve injury in rats.

We have examined the labeling pattern in the spinal dorsal horn by an intra-sciatic nerve injection of cholera toxin B subunit conjugated horseradish peroxidase (HRP) after transection of the posterior cutaneous nerve and inferior gluteal nerve, and found that the cholera toxin B subunit conjugated HRP labeling in lamina I was expanding into lamina II and there was a shrinking gap between lamina I and lamina III. This result suggests that A-fibre sprouting arise after peripheral nerve injury, but mainly from small calibre Adelta-fibres which terminate in lamina I.

Co-localization of 5-HT(1B/1D/1F) receptors and glutamate in trigeminal ganglia in rats.

Anti-migraine triptan drugs are 5-HT(1B/1D) receptor agonists which are thought to block the neurotransmitter/neuropeptide release from sensory nerve terminals and directly constrict blood vessel smooth muscles. In the present study, we have investigated the anatomical basis for a possible modulation of glutamate release from trigeminal ganglion neurons by 5-HT(1B/1D) receptor agonists and by 5-HT1F receptor agonists, using double immunohistochemical staining technique in the rat. The majority of 5-HT1B, 5-HT1D or 5-HT1F receptor positive neurons were also glutamate positive, but both 5-HT1B, 5-HT1D or 5-HT1F receptor single-labeled and glutamate single-labeled neurons were observed. These results suggest that 5-HT(1B/1D/1F) receptor agonists may modulate glutamate release, and that one mechanism of their anti-migraine action could be the blockade of glutamate release.

Colocalization of CGRP with 5-HT1B/1D receptors and substance P in trigeminal ganglion neurons in rats.

Vasodilatation in the dura mater has been implicated in migraine pathogenesis. Anti-migraine triptan drugs block vasodilatation by binding to 5-HT1B/1D receptors localized on the peripheral sensory terminals and dural blood vessel smooth muscles. Previous studies suggest that calcitonin gene-related peptide (CGRP) released from Adelta-fibres plays a more important role than substance P (SP) released from C-fibres in inducing dural vasodilatation and that one of the antimigraine mechanisms of triptan drugs is inhibiting CGRP release. In the present study, the relationship between CGRP and 5-HT1B/1D receptors, and between CGRP and SP in the trigeminal ganglion neurons in rats was examined by double immunohistochemical staining. CGRP, 5-HT1B, 5-HT1D and SP-positive trigeminal ganglion neurons were all predominantly small and medium-sized. In the trigeminal ganglia, approximately 50% of CGRP-positive neurons were 5-HT1B positive. Similarly, approximately 55% of CGRP-positive neurons were 5-HT1D immunoreactive. Approximately 50% of CGRP-positive neurons were SP-positive, while 93% of SP-positive neurons were CGRP-positive, suggesting that nearly all SP-positive neurons also contain CGRP. The fibre types of the 5-HT1B- and 5-HT1D-positive neurons were further investigated with an antibody against the A-fibre marker 200-kDa neurofilaments (NF200). Approximately 46% of the 5-HT1B-positive and 43% of the 5-HT1D-positive trigeminal ganglion neurons were also NF200 positive, indicating that many A-fibre trigeminal neurons express 5-HT1B or 5-HT1D receptors. These results support the hypothesis that one important action of antimigraine drugs is the inhibition of CGRP release and that Adelta-fibres may play an important role in migraine pathogenesis.

Localization of N-methyl-D-aspartate NR2B subunits on primary sensory neurons that give rise to small-caliber sciatic nerve fibers in rats.

In the present study we have used immunohistochemical staining and retrograde tracing techniques to investigate the relationship between the N-methyl-D-aspartate receptor NR2B subunits and small-diameter primary afferent dorsal root ganglion neurons that give rise to the sciatic nerve fibers. Three days after an intra-sciatic nerve injection of tetramethyl rhodamine isothiocyanate-conjugated wheat germ agglutinin which labels small-diameter primary afferents, many NR2B and wheat germ agglutinin-double-labeled cells ( approximately 70% of wheat germ agglutinin-labeled neurons) were observed in the L5 dorsal root ganglia. Three days after an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated Bandeiraea simplicifolia agglutinin isolectin B4 which labels predominantly non-peptidergic C-fiber primary afferents, NR2B and Bandeiraea simplicifolia agglutinin isolectin B4 double-labeled neurons ( approximately 90% of Bandeiraea simplicifolia agglutinin isolectin B4-labeled neurons) were also observed in the L5 dorsal root ganglion. Three days after an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated cholera toxin B subunit, only approximately 40% of cholera toxin B subunit-labeled neurons were NR2B positive and those labeled neurons tended to be small-sized. When calcitonin gene-related peptide and NR2B were labeled by a double immunofluorescent staining technique, we found that the majority of calcitonin gene-related peptide-positive neurons was NR2B immunoreactive (>90% of calcitonin gene-related peptide-positive neurons, and approximately 60% of NR2B-positive neurons) as well. Size frequency analysis also demonstrated that NR2B subunits were predominantly localized on the small and medium-sized neurons. These results suggest that NR2B subunits are predominantly expressed on small diameter primary afferents, and these NR2B containing N-methyl-D-aspartate receptors may play a role in the modulation of neurotransmitter release from primary afferent terminals.

Resection of sciatic nerve re-triggers central sprouting of A-fibre primary afferents in the rat.

We have investigated whether nerve injury or target deprivation is responsible for the injury induced central sprouting of A-fibres. Cholera toxin B subunit conjugated horseradish peroxidase was used to trace the termination of A-fibre primary afferents. Transection of the sciatic nerve induces central sprouting of sciatic myelinated A-fibre primary afferents into the spinal dorsal horn lamina II, which normally is the termination site of unmyelinated C-fibre primary afferents. The sprouting A-fibre terminals withdrew from lamina II after six to eight months. A second cut to the previously sectioned and ligated sciatic nerve re-triggered the central sprouting of A-fibre primary afferents into the spinal dorsal horn lamina II, suggesting that nerve injury per se rather than the deprivation of target tissues is the cause of central sprouting of A-fibre primary afferents.

Basal expression of bradykinin B1 receptor in peripheral sensory ganglia in the rat.

The bradykinin B1 receptor is thought to be induced by tissue injury and inflammation. In the present study, we have investigated whether there is a basal expression of B1 receptor in dorsal root ganglion (DRG) and trigeminal ganglion neurons in rats. A substantial number of neurons in both DRGs and trigeminal ganglia were found to be B1-immunoreactive in rats. Both small and medium-sized DRG neurons were B1-immunoreactive, suggesting that they are likely to be Adelta- or C-fibre neurons which are involved in nociceptive transmission. These results support a possible role for B1 receptors in the modulation of nociceptive sensory transmission.

Neurotrophins: peripherally and centrally acting modulators of tactile stimulus-induced inflammatory pain hypersensitivity.

Brain-derived neurotrophic factor (BDNF) is expressed in nociceptive sensory neurons and transported anterogradely to the dorsal horn of the spinal cord where it is located in dense core vesicles in C-fiber terminals. Peripheral inflammation substantially up-regulates BDNF mRNA and protein in the dorsal root ganglion (DRG) in a nerve growth factor-dependent fashion and results in novel expression of BDNF by DRG neurons with myelinated axons. C-fiber electrical activity also increases BDNF expression in the DRG, and both inflammation and activity increase full-length TrkB receptor levels in the dorsal horn. Sequestration of endogenous BDNF/neurotrophin 4 by intraspinal TrkB-Fc fusion protein administration does not, in noninflamed animals, change basal pain sensitivity nor the mechanical hypersensitivity induced by peripheral capsaicin administration, a measure of C fiber-mediated central sensitization. TrkB-Fc administration also does not modify basal inflammatory pain hypersensitivity, but does block the progressive hypersensitivity elicited by low-intensity tactile stimulation of inflamed tissue. BDNF, by virtue of its nerve growth factor regulation in sensory neurons including novel expression in A fibers, has a role as a central modulator of tactile stimulus-induced inflammatory pain hypersensitivity.

The progressive tactile hyperalgesia induced by peripheral inflammation is nerve growth factor dependent.

Experimental peripheral inflammation results in cutaneous mechanical hypersensitivity, and repeated low intensity mechanical stimulation of the inflamed skin induces a progressively incrementing hyperalgesia. We have now examined whether the elevation in nerve growth factor (NGF) induced by the inflammation contributes to this progressive hyperalgesia. An i.p. injection of anti-NGF antiserum (5 microliters g-1) 1 h before induction of inflammation by intraplantar complete Freund's adjuvant (CFA) injection and 24 h after, both reduced the basal inflammatory hypersensitivity and significantly attenuated the progressive increase of spontaneous activity, touch-, pinch- and A beta-afferent-evoked responses, and the progressive reduction of the mechanical threshold of biceps femoris/semitendinosus alpha motoneurones normally evoked by repeated (every 5 min) tactile stimulation of the inflamed hindpaw, in decerebrate-spinal rats. NGF contributes, therefore, to the progressive tactile hyperalgesia elicited by repeated touch stimulation of inflamed tissue.

Tachykinin NK1 receptor antagonist RP67580 attenuates progressive hypersensitivity of flexor reflex during experimental inflammation in rats.

We have now examined whether the tachykinin NK1 receptor is involved in mediating progressive hypersensitivity of spinal flexor motoneurons induced by repeated peripheral stimulation of inflamed tissue in decerebrate-spinal rats. The mechanical threshold of spinal flexor motoneurons was significantly decreased, and the touch- and pinch-evoked responses significantly increased, 48 h after intra-plantar injection of 100 microliters complete Freund's adjuvant. The threshold was further progressively decreased and the touch- and pinch-evoked responses increased over the 80 min testing period. Subcutaneous injection of the tachykinin NK1 receptor antagonist RP67580 (2-[1-imino-2-(2-methoxy phenyl) ethyl]-7,7 diphenyl-4 perhydroisoindolone-(3aR,7aR)) (20 min prior to the beginning of the test) at 1 mg and 10 mg/kg significantly attenuated the progressive decrease of mechanical withdrawal threshold, and the progressive increase of the touch- and pinch-evoked responses. The inactive enantiomer RP68651 (2-[1-imino-2-(2-methoxy phenyl) ethyl]-7,7 diphenyl-4 perhydroisoindolone-(3aS,7aS)) at 1 mg and 10 mg/kg had no significant effect. The present results indicate that substance P and its preferred tachykinin NK1 receptor are involved in mediating progressive hypersensitivity during inflammation.

Basal and touch-evoked fos-like immunoreactivity during experimental inflammation in the rat.

Fos-immunoreactivity can readily be induced in spinal cord neurones by noxious, but to a much more limited extent, by innocuous peripheral stimuli. The present study has investigated whether low intensity stimuli and electrical stimulation of A beta afferents elicit greater c-fos expression during the behavioural sensory hypersensitivity generated by experimental peripheral inflammation. We have examined the time-course of c-fos expression after inflammation produced by either an intra-plantar injection of the irritant turpentine oil or of complete Freund's adjuvant (CFA). In the former case, a significant initial expression in all dorsal horn laminae was followed by a gradual decrease, whereas after CFA injection, an initial expression limited to the superficial laminae subsequently extended into the deep laminae, with a decrease at 24 h and an increase in labelling at later times. Low intensity touch stimuli repeated for 10 min, when applied at 24 h and 48 h after CFA injection, elicited a significant increase in the number of Fos-immunoreactive neurons in both the superficial and deep laminae of the dorsal horn compared to non-inflamed animals. Electrical stimulation of the sciatic nerve 24 h post-CFA injection, at a strength sufficient only to activate A beta-afferents fibres (100 microA, 50 microseconds, 10 min), also elicited a significant increase in labelling relative to the same stimuli applied in control animals, especially in laminae V-VI. The present results demonstrate that low intensity cutaneous stimuli elicit a significantly greater increase in c-fos expression in dorsal horn neurons during peripheral inflammation and that A beta-afferent input contributes to this, a finding that may relate to the allodynia experienced during inflammation.

Peripheral cell types contributing to the hyperalgesic action of nerve growth factor in inflammation.

The contribution of nerve growth factor (NGF) to inflammatory hyperalgesia potentially could be mediated by any of the three peripheral cell types that express trkA, the high-affinity NGF receptor: inflammatory cells, sympathetic neurons, and primary sensory neurons. To investigate their relative involvement, the effects of sympathectomy and mast cell degranulation were examined on the local inflammation produced by an intraplantar injection of complete Freund's adjuvant in the adult rat. Sympathectomy, produced by neonatal guanethidine treatment, elevated basal NGF levels in the skin but did not attenuate a further increase in NGF during inflammation. Although the onset of inflammatory hyperalgesia was delayed in sympathectomized animals, peak sensitivity was not affected and was still NGF-dependent. In contrast, mast cell degranulation produced by several days of treatment with the cationic secretagogue compound 48/80, while also increasing basal NGF levels, prevented a further increase in NGF levels and attenuated hypersensitivity during inflammation. Neither manipulation modified the inflammatory upregulation of interleukin-1beta. We conclude that sympathetic neurons contribute transiently to inflammatory hyperalgesia, but that mast cells and sensory neurons are important sites for the sustained action of NGF in producing increased sensitivity during inflammation.

Involvement of neurokinin receptors in the induction but not the maintenance of mechanical allodynia in rat flexor motoneurones.

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.