Hind Limb Swelling Research Articles

N-demethylsinomenine metabolite and its prototype sinomenine activate mast cells via MRGPRX2 and aggravate anaphylaxis.

Sinomenine hydrochloride (SH) is commonly used in the treatment of rheumatoid arthritis. It activates mast cells and induces anaphylaxis in the clinical setting. Adverse drug reactions can be caused by activation of MAS-associated G protein-coupled receptor X2 (MRGPRX2) on mast cells. Because the ligand binding site of MRGPRX2 is easily contacted in dilute solvents, it can be activated by many opioid drug structures. N-Demethylsinomenine (M-3) has a similar chemical structure to that of the opioid scaffold and is a major metabolite of SH. We sought to clarify whether M-3 induces anaphylaxis synergistically with its prototype in a mouse model. Molecular docking computer simulations suggested a similar binding effect between M-3 and SH. M-3 was chemically synthesized and analyzed by surface plasmon resonance to reveal its affinity for MRGPRX2. Temperature monitoring, in vivo hindlimb swelling and exudation test, and in vitro mast cell degranulation test were used to explore the mechanism of MRGPrx2 mediated allergic reaction triggered by M-3. Reduced M-3-induced inflammation was evident in MrgprB2 (the ortholog of MRGPRX2) conditional (Cpa3-Cre/MrgprB2flox) knockout (MrgprB2-CKO) mice. Additionally, LAD2 human mast cells with MRGPRX2 knockdown showed reduced degranulation. M-3 activated LAD2 cells synergistically with SH as regulated by GRK2 signaling and IP3R/PLC/PKC/P38 molecular signaling pathways. The results indicate that the M-3 metabolite can activate mast cells synergistically with its prototype SH via MRGPRX2 and aggravate anaphylaxis. These findings provide important insights into drug safety.

Therapeutic effect and mechanism of Mailuo Shutong Pills on posterior limb swelling caused by femur fracture in rats based on intestinal flora and intestinal metabolism

This study aimed to investigate the protective effect and underlying mechanism of Mailuo Shutong Pills(MLST) on posterior limb swelling caused by femur fracture in rats. The rats were randomly divided into a sham operation group, a model group, a low-dose MLST group(1.8 g·kg~(-1)·d~(-1)), a high-dose MLST group(3.6 g·kg~(-1)·d~(-1)), and a positive drug group(60 mg·kg~(-1)·d~(-1) Maizhiling Tablets). The femur in the sham operation group was exposed and the wound was sutured, while the other four groups underwent mechanical damage to cause femur fracture. The rats were treated with corresponding drugs by gavage 7 days before modeling and 5 days after modeling, while those in the sham operation group and the model group were given an equivalent dose of distilled water by gavage. Hematoxylin-eosin(HE) staining was used to detect the pathological injury of the posterior limb muscle tissues in rats, and the degree of hind limb swelling was measured. The enzyme-linked immunosorbent assay(ELISA) kit was used to detect the expression levels of interleukin-6(IL-6), interleukin-1β(IL-1β), and tumor necrosis factor-α(TNF-α) in the serum of rats in each group. The activity of superoxide dismutase(SOD), malondialdehyde(MDA), catalase(CAT), and glutathione peroxidase(GSH-Px) in rat serum was also measured. Western blot was used to detect the protein expression levels of heme oxygenase 1(HO-1), NAD(P)H quinone oxidoreductase 1(NQO1), and nuclear transcription factor E2-related factor 2(Nrf2) in rat posterior limb muscle tissues. The changes in the intestinal flora and intestinal metabolites in rats were detected by 16S rDNA sequencing and ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS), respectively, to explore the underlying mechanism of MLST in treating posterior limb swelling caused by femur fracture in rats. Compared with the model group, MLST significantly improved the degree of posterior limb swelling in rats, reduced the levels of serum inflammatory factors, and alleviated oxidative stress injury. The HE staining results showed that the inflammatory infiltration in the posterior limb muscle tissues of rats in the MLST groups was significantly improved. Western blot results showed that MLST significantly increased the protein expression of HO-1, NQO1, and Nrf2 in rat posterior limb muscle tissues compared with the model group. The 16S rDNA sequencing results showed that MLST improved the disorder of intestinal flora in rats after femur fracture. The UPLC-MS/MS results showed that MLST significantly affected the bile acid biosynthesis and metabolism pathway in the intestine after femur fracture, and the Spearman analysis confirmed that the metabolite deoxycholic acid involved in bile acid biosynthesis was positively correlated with the abundance of Turicibacter. The metabolite cholic acid was positively correlated with the abundance of Papilibacter, Staphylococcus, and Intestinimonas. The metabolite lithocholic acid was positively correlated with Papilibacter and Intestinimonas. The above results indicated that MLST could protect against the posterior limb swelling caused by femur fracture in rats. This protective effect may be achieved by improving the pathological injury of the posterior limb muscle, reducing the expression levels of inflammatory and oxidative stress-related factors in serum, reducing the oxidative injury of the posterior limb muscle, improving intestinal flora, and balancing the biosynthesis of bile acids in the intestine.

Septic Arthritis and Granulomatous Osteomyelitis in a Bearded Dragon (Pogona vitticeps) Caused by Mycobacterium sp.

A 3-yr-old female bearded dragon (Pogona vitticeps) was presented to the Exotic Pet and Wildlife Veterinary Teaching Hospital at the National Autonomous University of Mexico with a 3-day history of right hindlimb swelling. Radiographs revealed lysis of the right stifle and tarsal bone. Fine-needle aspiration from the stifle revealed large numbers of macrophages and giant cells, and Ziehl-Neelsen stain revealed intracytoplasmic acid-fast bacilli-like bacteria. Standard aerobic culture was performed, with negative results. Pain management was provided with meloxicam (0.2 mg/kg PO q24h) and tramadol (11 mg/kg PO q12h); the owner declined antimicrobial therapy. Three weeks later, radiographs revealed the progression of the lytic lesions to the distal femur, proximal tibia, and tarsal bones. One month later, the patient presented for left hindlimb swelling. Follow-up radiographs revealed a total loss of the right stifle and the tibiotarsal and tarsometatarsal joints, as well as new lytic lesions at the left stifle and tibiotarsal joints. Based on the grave prognosis, the lizard was euthanized. At necropsy, granuloma-like lesions were found at the stifles and the coxofemoral, tibiotarsal, and tarsometatarsal joints. Imprints made from these lesions revealed acid-fast bacilli. No other gross lesions were identified. Microscopic review of the tissues revealed severe granulomatous osteomyelitis and myositis, as well as a severe histiocytic and heterophilic hepatitis with acid-fast intrahistiocytic bacilli. Polymerase chain reaction results confirmed these bacteria as nontuberculous mycobacteria. To the authors' knowledge, this is the first postmortem report of septic arthritis associated with Mycobacterium spp. in a bearded dragon; only two other cases have been reported, both without postmortem findings.

Therapeutic effects of Durian wood bark extract on a rat model of rheumatoid arthritis

BackgroundRheumatoid arthritis (RA) is a common immune-mediated inflammatory disease characterized by increased inflammation of synovial joint, and often associated with disability. Although several studies have demonstrated the medicinal properties of durian, little is known about the role of durian wood bark for medicinal purposes. Thus, this study investigated the anti-arthritic activity of durian wood bark extract in a rat model of rheumatoid arthritis. MethodsThe rats were divided into five groups, including control, RA model, and RA model treated with durian wood bark extract (20, 30, and 40mg/kg/day for 14 days). The effects of treatment were evaluated by clinical, as well as histological changes in the ankle joints, and the expression level of inducible nitric oxide synthase (iNOS). ResultsA complete Freund's adjuvant (CFA)-induced RA model in rats was successfully, characterized by the swelling of hind limbs, histopathological changes in ankle joints, and the upregulation of iNOS expression. The administration of durian wood bark extract at a dose of 40mg/kg attenuated all parameters analyzed in CFA-induced RA model in rats. ConclusionAmelioration of hind limb swelling, histopathological changes, and iNOS expression in the RA model indicates that durian wood bark extract can be considered as a new treatment alternative that reduces joint symptoms, as well as a future area of research in humans.

Osteosarcoma in the femur of a horse

SummaryA 27‐year‐old Arabian pony gelding presented for evaluation of weight loss, intermittent sheath oedema, persistent neutropenia and thrombocytopenia, and acute left hindlimb swelling and gait abnormality. Clinical findings included swelling, heat and sensitivity localised over the left greater trochanter, mild to moderate ventral and sheath oedema, a left hindlimb post‐legged gait, and off‐loading of weight from the left hindlimb at rest. Initially, neutropenia and thrombocytopenia were confirmed on bloodwork, but neutrophilia and thrombocytopenia persisted as the case progressed. Diagnostic imaging (radiography and percutaneous ultrasonography) of the left hindquarters revealed an aggressive, mixed proliferative and lytic bony lesion of the proximal left femur as well as associated muscle fibre disruption and a soft tissue mass. A percutaneous core biopsy of the lesion led to the diagnosis of osteoblastic osteosarcoma on histopathology. Pain and inflammation associated with the lesion was medically managed in the hospital with mild improvement. Additionally, palliative radiation was performed under general anaesthesia. Unfortunately, before a response to palliative radiation could be assessed, the patient was subjected to euthanasia due to development of acute neurological signs.

Therapeutic effects of Durian wood bark extract on a rat model of rheumatoid arthritis

BackgroundRheumatoid arthritis (RA) is a common immune-mediated inflammatory disease characterized by increased inflammation of synovial joint, and often associated with disability. Although several studies have demonstrated the medicinal properties of durian, little is known about the role of durian wood bark for medicinal purposes. Thus, this study investigated the anti-arthritic activity of durian wood bark extract in a rat model of rheumatoid arthritis. MethodsThe rats were divided into five groups, including control, RA model, and RA model treated with durian wood bark extract (20, 30, and 40mg/kg/day for 14 days). The effects of treatment were evaluated by clinical, as well as histological changes in the ankle joints, and the expression level of inducible nitric oxide synthase (iNOS). ResultsA complete Freund's adjuvant (CFA)-induced RA model in rats was successfully, characterized by the swelling of hind limbs, histopathological changes in ankle joints, and the upregulation of iNOS expression. The administration of durian wood bark extract at a dose of 40mg/kg attenuated all parameters analyzed in CFA-induced RA model in rats. ConclusionAmelioration of hind limb swelling, histopathological changes, and iNOS expression in the RA model indicates that durian wood bark extract can be considered as a new treatment alternative that reduces joint symptoms, as well as a future area of research in humans.

MiR-130a/Ndrg2 Axis Inhibits the Proliferation of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis.

Studies have found that N-myc downstream-regulated gene 2 (Ndrg2) is involved in the progression of rheumatoid arthritis (RA); however, the specific mechanism still remains unclear. Gene expression profiles in the tibial joints of the collagen-induced rheumatoid arthritis model were obtained using Gene Expression Omnibus database. Western blot and real-time PCR were respectively performed to determine the expression of Ndrg2 and gene messenger RNA. Cell viability was measured by Cell Counting Kit-8 (CCK-8) method, and cell cycle was detected by flow cytometry. Cell scratch assays were carried out to detect migration. The binding ability of miR-130a to Ndrg2-3'-UTR was predicted by TargetScan website and confirmed by dual luciferase assay. A collagen-induced arthritis rat model was constructed to observe the effects of miR-130a on arthritis index, hind limb swelling, volume of rat hind paw, and inflammation. Ndrg2 was found downregulated in RA tissues, and knockdown of Ndrg2 promoted fibroblast-like synoviocytes (FLS) proliferation and inflammation, while overexpressed Ndrg2 produced opposite results. Ndrg2 was predicted as a target gene for miR-130a, and miR-130a mimic promoted FLS proliferation, while miR-130a inhibitor suppressed FLS proliferation. Moreover, we found that miR-130a antagomir could significantly reduce the arthritis index, swelling degree, foot volume, and inflammatory factor levels; inhibit the expression of miR-130a; and promote the expression of Ndrg2. The miR-130a/Ndrg2 axis signaling pathway is involved in the progression of RA. Our findings provide a theoretical basis for the clinical treatment of RA.

Effects of Intramuscular Heating-needle Stimulation in Controlling Adjuvant-induced Muscle Nociception in Rats: Differential Roles of Thalamic Purinergic P2X3 Receptors

Here we investigated effects of intramuscular (i.m.) heating-needle stimulation on persistent muscle nociception evoked by i.m. injection of different doses (50–200 µl) of complete Freund’s adjuvant (CFA) in rats. Paw withdrawal reflexes evoked by noxious mechanical and heat stimulation as well as hind limb swelling were determined prior to and two weeks after the CFA injection. The unilateral injection of CFA induced a dose-related and long-lasting (5–14 d), bilateral secondary mechanical hyperalgesia and heat hypoalgesia associated with long-term limb swelling. A period of 30–45 min 43 °C heating-needle stimulation significantly enhanced the i.m. CFA-induced bilateral heat hypoalgesia and alleviated hind limb swelling. In contrast, 30–45 min 46 °C heating-needle stimulation markedly enhanced both mechanical hyperalgesia and heat hypoalgesia, but failed to influence the CFA-induced hind limb swelling. Microinjection of P2X3 receptor antagonist A-317491 (0.5–4.5 nmol/0.5 µl) into the thalamic ventromedial (VM) nucleus dose-dependently inhibited the 43 °C and 46 °C heating-needle stimulation-induced heat hypoalgesia, whereas the 46 °C heating-needle stimulation-induced mechanical hyperalgesia was significantly prevented by microinjection of A-317491 into the thalamic mediodorsal (MD) nucleus. In contrast, the hind limb swelling was not affected by the microinjection of A-317491 into the thalamic VM or MD nucleus. The present study indicates that in the CFA-induced persistent muscle nociception condition, 43 °C heating-needle stimulation selectively increases descending inhibition, which effect is modulated by the thalamic VM nucleus. In addition to the antinociceptive role of P2X3 receptors in the thalamic VM nucleus, P2X3 receptors within the thalamic MD nucleus participate in the descending facilitation evoked by i.m. 46 °C heating-needle stimulation.

The Initiation, but Not the Persistence, of Experimental Spondyloarthritis Is Dependent on Interleukin-23 Signaling.

IL-17A is a central driver of spondyloarthritis (SpA), its production was originally proposed to be IL-23 dependent. Emerging preclinical and clinical evidence suggests, however, that IL-17A and IL-23 have a partially overlapping but distinct biology. We aimed to assess the extent to which IL-17A-driven pathology is IL-23 dependent in experimental SpA. Experimental SpA was induced in HLA-B27/Huβ2m transgenic rats, followed by prophylactic or therapeutic treatment with an anti-IL23R antibody or vehicle control. Spondylitis and arthritis were scored clinically and hind limb swelling was measured. Draining lymph node cytokine expression levels were analyzed directly ex vivo, and IL-17A protein was measured upon restimulation with PMA/ionomycin. Prophylactic treatment with anti-IL23R completely protected against the development of both spondylitis and arthritis, while vehicle-treated controls did develop spondylitis and arthritis. In a therapeutic study, anti-IL23R treatment failed to reduce the incidence or decrease the severity of experimental SpA. Mechanistically, expression of downstream effector cytokines, including IL-17A and IL-22, was significantly suppressed in anti-IL23R versus vehicle-treated rats in the prophylactic experiments. Accordingly, the production of IL-17A upon restimulation was reduced. In contrast, there was no difference in IL-17A and IL-22 expression after therapeutic anti-IL23R treatment. Targeting the IL-23 axis during the initiation phase of experimental SpA—but not in established disease—inhibits IL-17A expression and suppresses disease, suggesting the existence of IL-23-independent IL-17A production. Whether IL-17A can be produced independent of IL-23 in human SpA remains to be established.

Lymphatic delivery of etanercept via nanotopography improves response to collagen-induced arthritis

BackgroundEvidence suggests lymphatic function mediates local rheumatoid arthritis (RA) flares. Yet biologics that target the immune system are dosed systemically via the subcutaneous (SC) administration route, thereby inefficiently reaching local lymphatic compartments. Nanotopography has previously been shown to disrupt tight cellular junctions, potentially enhancing local lymphatic delivery and potentially improving overall therapeutic efficacy.MethodWe first characterized nanotopography (SOFUSA™) delivery of an anti-TNF drug, etanercept, by comparing pharmacokinetic profiles to those obtained by conventional SC, intravenous (IV), and intradermal (ID) routes of administration, and assessed uptake of radiolabeled etanercept in draining lymph nodes (LNs) in single dosing studies. We then compared etanercept efficacy in a progressive rat model of collagen-induced arthritis (CIA), administered systemically via SC route of administration; via the regional lymphatics through ID delivery; or through a nanotopography (SOFUSA™) device at 10, 12, and 14 days post CIA induction. Measurements of hind limb swelling and near-infrared fluorescence (NIRF) imaging of afferent lymph pumping function and reflux were conducted on days 11, 13, and 18 post CIA induction and compared to untreated CIA animals. Univariate and multivariate analysis of variance were used to compare the group differences for percentage swelling and lymphatic contractile activity.ResultsEven though all three modes of administration delivered an equal amount of etanercept, SOFUSA™ delivery resulted in increased lymphatic pumping and significantly reduced swelling as compared to untreated, ID, and SC groups. Pharmacokinetic profiles in serum and LN uptake studies showed that using the nanotopography device resulted in the greatest uptake and retention in draining LNs.ConclusionsLocoregional lymphatic delivery of biologics that target the immune system may have more favorable pharmacodynamics than SC or IV administration. Nanotopography may provide a more efficient method for delivery of anti-TNF drugs to reverse impairment of lymphatic function and reduce swelling associated with RA flares.

Lymph Node Transplantation Decreases Swelling and Restores Immune Responses in a Transgenic Model of Lymphedema.

IntroductionSecondary lymphedema is a common complication of cancer treatment and recent studies have demonstrated that lymph node transplantation (LNT) can decrease swelling, as well as the incidence of infections. However, although these results are exciting, the mechanisms by which LNT improves these pathologic findings of lymphedema remain unknown. Using a transgenic mouse model of lymphedema, this study sought to analyze the effect of LNT on lymphatic regeneration and T cell-mediated immune responses.MethodsWe used a mouse model in which the expression of the human diphtheria toxin receptor is driven by the FLT4 promoter to enable the local ablation of the lymphatic system through subdermal hindlimb diphtheria toxin injections. Popliteal lymph node dissection was subsequently performed after a two-week recovery period, followed by either orthotopic LNT or sham surgery after an additional two weeks. Hindlimb swelling, lymphatic vessel regeneration, immune cell trafficking, and T cell-mediated immune responses were analyzed 10 weeks later.ResultsLNT resulted in a marked decrease in hindlimb swelling, fibroadipose tissue deposition, and decreased accumulation of perilymphatic inflammatory cells, as compared to controls. In addition, LNT induced a marked lymphangiogenic response in both capillary and collecting lymphatic vessels. Interestingly, the resultant regenerated lymphatics were abnormal in appearance on lymphangiography, but LNT also led to a notable increase in dendritic cell trafficking from the periphery to the inguinal lymph nodes and improved adaptive immune responses.ConclusionsLNT decreases pathological changes of lymphedema and was shown to potently induce lymphangiogenesis. Lymphatic vessels induced by LNT were abnormal in appearance, but were functional and able to transport antigen-presenting cells. Animals treated with LNT have an increased ability to mount T cell-mediated immune responses when sensitized to antigens in the affected hindlimb.

Massive haematoma formation associated with proximal popliteal artery haemangioendothelioma in a dog

A mixed breed dog presented with diffuse unilateral hind limb swelling, which ultrasound and cytology confirmed to be caused by severe haematoma formation. Multi-detector computed tomography (MDCT) angiography allowed distinct visualisation of an anomalous segment of the proximal popliteal artery, the presumed origin of the self-sustaining haematoma. Histopathology classified the malformed vessel as a haemangioendothelioma, a neoplasia of intermediate malignancy. Considering this as differential diagnosis to a neoplastic vascular alteration of high malignancy (such as haemangiosarcoma) might alter choice of treatment in future cases with similar clinical and imaging findings.

Bilateral degenerative suspensory desmitis with acute rupture in a Standardbred colt

SummaryA 3‐month‐old Standardbred colt was examined for acute, bilateral hindlimb swelling and lameness. Serum chemistry demonstrated elevated muscle enzymes (AST, ALT, LDH and CK). Radiographs of the hindlimbs demonstrated intact proximal sesamoid bones that were displaced distally and subluxation of the pastern joints. Ultrasonography of the affected areas revealed large, diffuse hypoechoic areas in the bodies of both hind suspensory ligaments consistent with bilateral rupture. Histology of the lesions was consistent with degenerative suspensory desmitis with acute rupture.

Unilateral hindlimb swelling may be a sign of serious disseminated neoplasia in horses

Unilateral hindlimb swelling may be a sign of serious disseminated neoplasia in horses

FOXC2 haploinsufficient mice are a model for human autosomal dominant lymphedema-distichiasis syndrome.

Lymphedema-distichiasis (LD) (OMIM 153400) is a rare autosomal-dominant condition characterized by pubertal onset of lower limb lymphedema and an aberrant second row of eyelashes arising from the meibomian glands. In some patients cardiac, skeletal and other defects coexist. We previously identified inactivating, nonsense and frameshift mutations in the forkhead transcription factor FOXC2 in affected members of LD families. To further delineate the relationship of FOXC2 deficiency to the clinical (and lymphangiodysplastic) phenotype in this syndrome, we performed dynamic lymphatic imaging and immunohistochemical examination of lymphatic tissues in mice heterozygous (+/-) for a targeted disruption of Foxc2. Adult heterozygote mice characteristically exhibited a generalized lymphatic vessel and lymph node hyper plasia and rarely exhibited hindlimb swelling. Retrograde lymph flow through apparently incompetent interlymphangion valves into the mesenteric nodes, intestinal wall and liver was also observed. In addition, Foxc2 +/- mice uniformly displayed distichiasis. We conclude that Foxc2 haploinsufficient mice mimic closely the distinctive lymphatic and ocular phenotype of LD patients. Furthermore, the craniofacial, cardiovascular and skeletal abnormalities sometimes associated with LD have previously been shown to be fully penetrant in homozygous Foxc2 null mice. This Foxc2 mutant mouse thus provides an ideal model for exploring molecular mechanisms and physiologic events in mesenchymal differentiation associated with lymphatic growth and development and the clinical abnormalities seen in human LD syndrome.

Inflammatory Arthritic Process, Iridocyclitis and Immune Response to Articular and Ocular Antigens in Wistar Rats Injected with T. gondii Trophozoites

The present study deals with the potential role of T. gondii in inducing an arthritic inflammatory process. Wistar rats were injected subcutaneously (sc) into the right footpad with viable T. gondii trophozoites emulsified in incomplete Freund's adjuvant (IFA). The control group was injected with IFA. All parasite-injected animals developed a local inflammatory process characterized by hind limb swelling and marked restriction of ankle motility approximately 25 days after injection. Histopathogical studies of the joints, carried out 90 days after injection, revealed intense mononuclear infiltration, proliferation of granulation tissue, giant cells and necrosis in the synovia of 90% of T. gondii -injected rats. Strikingly, 40% (4/10) of the parasite-injected animals developed iridocyclitis, which was characterized by intense mononuclear infiltration around the iris–ciliary microvasculature in two animals and a slightly pronounced infiltrate of polymorphonuclear and mononuclear cells in two other animals. Antibodies to soluble T. gondii antigens (STAg) were detected in all parasite-injected rats. Antibodies against articular and ocular antigens such as proteoglycans, type II collagen, retinal S antigen and iris antigens were detected by ELISA in 40, 80, 70 and 70% of T. gondii -injected animals, respectively. Control animals injected with IFA failed to develop any articular or ocular process or humoral immune response. The present study demonstrated that footpad sc injection of Wistar rats with viable T. gondii trophozoites was able to induce a localized inflammatory arthritic process which, in some of the animals, was accompanied by iridocyclitis and immune response against articular and ocular components.

URINARY OBSTRUCTION SECONDARY TO A RETROPERITONEAL CARCINOMA IN A DOG

A 7‐year‐old, intact, anestrous, female Doberman pinscher was presented with anorexia and hindlimb swelling of three days duration. Renal failure was documented. Survey radiographs revealed patchy alveolar consolidation and bilateral renomegaly with increased retroperitoneal and sublumbar soft tissue opacification. Renal ultrasonography showed bilateral hydronephrosis with ectatic ureters. A retroperitoneal carcinoma was identified via fine needle aspiration. Percutaneous nephropyelocentesis and antegrade nephrography further delineated the hydronephrosis and ureteral obstruction.

The influence of sustained opioid receptor blockade in a model of long-term, localized inflammatory pain in rats

Rats were subcutaneously implanted with minipumps delivering naloxone (3.0 mg/kg/h) or distilled water. One day later, they were inoculated in the plantar surface of the right hind paw with Mycobacterium butyricum. Naloxone blocked the antinociceptive action of the mu-agonist, morphine, and the kappa-agonist, U69,593, and led to a sustained reduction in food and water intake. Thus, opioid receptors were effectively occupied. Rats receiving naloxone showed significantly less hindlimb swelling on days 2 and 3 post-implantation. On day 2 but not 5 post-implantation, the hyperalgesic response of the inoculated paw to noxious pressure was potentiated in rats receiving naloxone. At six days post-implantation, pumps were removed. Ten days after removal, the inflammation and hyperalgesia had spread to the contralateral hindlimb and to the forelimbs. The degree of this transfer was less pronounced in rats which had been receiving naloxone. These data suggest that opioids, via kappa-receptors, play a role in the control of nociception under inflammatory pain: however, this role may not be indispensable. Further, the processes governing the development and spread of inflammatory disease may be modulated by opioid mechanisms.

Bromocriptine microcapsules inhibit ornithine decarboxylase activity induced by Freund's complete adjuvant in lymphoid tissues of male rats.

Arthritis is produced in male rats within 9-10 days after a single injection of Freund's complete adjuvant (FCA) at the base of the tail. When bromocriptine, a dopaminomimetic that suppresses PRL secretion, was given in form of long-acting microcapsules (CBLA) 3 days before FCA, the hind limb swelling was significantly reduced by 70%. Here, we showed that plasma PRL levels were significantly elevated (by 150% over controls) during the 6-day period after FCA, particularly at night. Further, within 1-4 days after FCA inoculation, marked increases in ornithine decarboxylase (ODC) activity occurred in bone marrow, thymus, spleen, and lymph nodes (by 190%, 160%, 80% and 75% over control values, respectively). In FCA-treated rats, the circadian rhythm of thymic ODC showed that an important enhancement of activity occurred during the dark phase, which correlated with the peak of PRL secretion (between 2200-0400 h). Finally, pretreatment with CBLA significantly inhibited the induction of ODC in response to FCA in thymus, spleen, and lymph nodes (by 65%, 80%, and 45%, respectively) and inhibited it more weakly in the bone marrow. This in vivo study leaves little doubt about the existence of a PRL-dependent immuno-stimulatory mechanism, probably involved in the pathogenesis of adjuvant arthritis.