Comparison of inflammatory changes in established type II collagen- and adjuvant-induced arthritis using outbred Wistar rats

Modulatory role of prenatal alcohol exposure and adolescent stress on the response to arthritis challenge in adult female rats

Background

There are known environmental risk factors associated with rheumatoid arthritis; however, less is known regarding how the prenatal environment impacts later-life risk for rheumatoid arthritis. Based on preliminary clinical data suggesting that individuals with fetal alcohol spectrum disorder (FASD) are at higher risk for autoimmune disorders, this study investigated the modulatory impact of prenatal alcohol exposure (PAE) on the inflammatory disease profile in an adjuvant-induced arthritis rat model.

Methods

Pregnant rats received liquid ethanol or control diet throughout gestation. To model the increased exposure to stressors often experienced by individuals with FASD, adolescent offspring were exposed to chronic mild stress (CMS) or remained undisturbed. In adulthood, experimental arthritis was initiated and rats terminated either at the peak or following resolution from inflammation to assess endocrine, immune, and histopathological outcomes.

Findings

PAE rats had an increased incidence and severity of, and impaired recovery from, arthritis. Increased joint damage was observed in PAE animals, even in the face of apparent recovery from the clinical signs of arthritis, while it appeared that oestradiol may have a protective role. Moreover, with the combination of PAE and adolescent stress, increased macrophage density was detected in the synovium of PAE but not control rats.

Interpretation

These findings demonstrate that PAE alters the severity and course of arthritis, highlighting the potential immunomodulatory impact of adverse prenatal exposures. In particular, these data have implications for understanding preliminary data that suggest a heightened propensity for autoimmune disorders in individuals with FASD.

Micro-CT imaging analysis for the effects of ibandronate and eldecalcitol on secondary osteoporosis and arthritis in adjuvant-induced arthritis rats

We investigated the effects of ibandronate, a bisphosphonate; eldecalcitol, an active vitamin D3 analogue; and combination treatment with both agents on secondary osteoporosis and arthritis using rats with adjuvant-induced arthritis. Arthritis was induced in 8-week-old male Lewis rats. Rats were randomized into four treatment groups and an untreated normal control group: ibandronate, eldecalcitol, ibandronate + eldecalcitol, vehicle, and control. Paw thickness was measured to evaluate arthritis. Joint destruction was evaluated histomorphometrically by the ankle joint stained with Fast Green and safranin O. The femur and lumbar spine were scanned using dual-energy X-ray absorptiometry, and the distal femur was scanned using micro-computed tomography for bone mineral density (BMD) and trabecular microstructural evaluations. Ibandronate and/or eldecalcitol increased BMD in both the lumbar vertebrae and femur and improved several microstructural parameters (bone volume/total volume, structure model index, trabecular number, and trabecular separation of the distal femur). In addition, there was an additive effect of combination treatment compared with single treatments for most trabecular parameters, including BMD and bone volume. However, ibandronate and/or eldecalcitol did not inhibit arthritis and joint destruction. Combination treatment with ibandronate and eldecalcitol may be effective for secondary osteoporosis associated with arthritis.

Hybrid micelles containing methotrexate-conjugated polymer and co-loaded with microRNA-124 for rheumatoid arthritis therapy

Purpose: Methotrexate (MTX) is a first-line drug for rheumatoid arthritis (RA)therapy. However, MTX monotherapy often results in irreversible joint damage due to its slow onset of action and long duration. microRNA-124 (miR-124) has shown direct bone protection activity against RA. A co-delivery system for MTX and microRNA combination may provide therapeutic synergy. Methods: Methotrexate-conjugated polymer hybrid micelles (M-PHMs) were prepared by self-assembly of two functional amphiphilic polymers (MTX-PEI-LA and mPEG-LA) at an optimized weight ratio. Incorporation of microRNA was achieved through electrostatic interactions between microRNA and cationic polymer MTX-PEI-LA. Cellular uptake, endosome escape, biodistribution, and therapeutic efficacy of M-PHMs/miR-124 complexes were investigated and evaluated in RAW264.7 cells and a rat adjuvant-induced arthritis (AIA) model. Results: M-PHMs/miR-124 complexes exhibited folate receptor-mediated uptake in activated RAW264.7 cells. miR-124 was able to escape from the endosome and down-regulate nuclear factor of activated T cells cytoplasmic1 (NFATc1). M-PHMs/miR-124 complexes accumulated in inflamed joints of AIA rats and showed superior therapeutic efficacy through both anti-inflammatory effect and direct bone protective effect. Combination of miR-124 and MTX in these micelles induced disease remission. Conclusions: M-PHMs/miR-124 was highly effective against RA through therapeutic synergy. Additional studies are warranted to further investigate its therapeutic potential and delineate its mechanisms of action.

Animal Models of Peripheral Pain: Biology Review and Application for Drug Discovery

Pain is a complex constellation of cognitive, unpleasant sensory, and emotional experiences that primarily serves as a survival mechanism. Pain arises in the peripheral nervous system and pain signals synapse with nerve tracts extending into the central nervous system. Several different schemes are used to classify pain, including the underlying mechanism, tissues primarily affected, and time-course. Numerous animal models of pain, which should be employed with appropriate Institutional Animal Care and Use approvals, have been developed to elucidate pathophysiology mechanisms and aid in identification of novel therapeutic targets. The variety of available models underscores the observations that pain phenotypes are driven by several distinct mechanisms. Pain outcome measurement encompasses both reflexive (responses to heat, cold, mechanical and electrical stimuli) and nonreflexive (spontaneous pain responses to stimuli) behaviors. However, the question of translatability to human pain conditions and potential treatment outcomes remains a topic of continued scrutiny. In this review we discuss the different types of pain and their mechanisms and pathways, available rodent pain models with an emphasis on type of pain stimulations and pain outcome measures and discuss the role of pathologists in assessing and validating pain models.

Free and nanoencapsulated vitamin D3 : effects on E-NTPDase and E-ADA activities in an animal model with induced arthritis

The effect of vitamin D3 in oral solution (VD3 ) and vitamin D3 -loaded nanocapsules (NC-VD3 ) was analysed in animals with complete Freund's adjuvant (CFA) induced arthritis (AR). For this purpose, we evaluated scores for arthritis, thermal hyperalgesia and paw oedema, as well as histological analyses and measurements of the activity of the ectonucleoside triphosphate diphosphohydrolase (E-NTPDase) and ecto-adenosine deaminase (E-ADA) enzymes in rat lymphocytes. Haematological and biochemical parameters were also determined. The doses administered were 120 UI/day of VD3 and 15.84 UI/day of NC-VD3 . Fifteen days after the induction of AR, the groups were treated for 15 days with vitamin D3 . The results demonstrated that VD3 was able to reduce arthritis scores, thermal hyperalgesia and paw oedema in rats with CFA-induced arthritis. However, treatment with NC-VD3 did not reduce arthritis scores. The histological analyses showed that both formulations were able to reduce the inflammatory changes induced by CFA. The activity of E-NTPDase in rat lymphocytes was higher in the AR compared with the control group, while the activity of E-ADA was lower. This effect was reversed after the 15-day treatment. Data from this study indicates that both forms of vitamin D3 seem to contribute to decreasing the inflammatory process induced by CFA, possibly altering the activities of ectoenzymes. Copyright © 2016 John Wiley & Sons, Ltd.

SIGNIFICANCE OF THE STUDY

The effects promoted by both formulations of vitamin D3 , either in oral solution or nanoencapsulated form, strongly suggests the softening of the inflammatory process induced by complete Freund's adjuvant (CFA), possibly altering the E-NTPDase and E-ADA activities. However, it is known that vitamin D has a beneficial effect on the modulation of the immune system components responsible for the inflammatory process. Moreover, the establishment of responses to treatment with vitamin D3 may provide an alternative for inhibiting the proinflammatory response, assisting in our understanding of the immunopathology of this disease and possibly improving the signs and symptoms that hinder the quality of life of patients with rheumatoid arthritis.

HIGHLIGHTS

Evaluation of the effects on the E-NTPDase and E-ADA activities in an animal model of induced arthritis. Two formulations of vitamin D3 were used: form oral solution and nanoencapsulated. Vitamin D3 seems to contribute to the inflammatory process induced by CFA. Vitamin D3 possibly alters the E-NTPDase and E-ADA activities. Vitamin D3 may be an alternative supplementary treatment for chronic arthritis.

Improvement of spontaneous locomotor activity with JAK inhibition by JTE-052 in rat adjuvant-induced arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disease that leads to joint destruction, disability, and decreased quality of life (QOL). Inhibition of Janus kinase (JAK) signaling ameliorates articular inflammation and joint destruction in animal models of RA, but its effects on behaviors indicating well-being are poorly understood. In this study, we evaluated the effect of JAK inhibition on spontaneous locomotor activity in rats with adjuvant-induced arthritis, a rodent model of RA.

METHODS

Arthritis was induced in male Lewis rats by a single subcutaneous injection of Freund's complete adjuvant. The novel JAK inhibitor JTE-052 was orally administered for 7 days after the onset of arthritis.

RESULTS

Induction of arthritis suppressed the spontaneous locomotor activity of the rats. Administration of JTE-052 completely improved the spontaneous locomotor activity, with partial reductions in articular inflammation and joint destruction. Hyperalgesia and motor functions were also improved, but the efficacy was not complete. However, serum interleukin (IL)-6 levels were completely decreased at 4 h after administration of the first dose of JTE-052.

CONCLUSIONS

This study demonstrated that JAK inhibition improved the spontaneous locomotor activity of rats with adjuvant-induced arthritis, in association with amelioration of pain and physical dysfunction as a consequence of suppression of joint inflammation. Moreover, although further studies are needed, there was possible participation of IL-6 downregulation in the improvement of locomotor activity by JAK inhibition.

Endothelial dysfunction in an ovine model of collagen-induced arthritis

BACKGROUND

Rheumatoid arthritis (RA) induces systemic inflammation, producing a range of co-morbidities including cardiovascular disease. An early vascular change is endothelial dysfunction, characterized by reduced endothelium-dependent vasodilation. The aim of this study was to assess endothelial function in isolated coronary and digital arteries using an ovine model of collagen-induced RA.

METHODS

Sheep were culled following induction of arthritis, and their endothelial function was compared to that of normal sheep. Paired arterial segments were mounted in a wire myograph and dilated with endothelium-dependent vasodilators [bradykinin, serotonin, carbachol and adenosine diphosphate (ADP); linked to either Gi or Gq signalling pathways] and endothelium-independent dilators (adenosine and sodium nitroprusside) to construct cumulative concentration-response curves.

RESULTS

Coronary arteries from arthritic sheep exhibited a significantly greater EC50 value for bradykinin-induced relaxation compared to non-arthritic controls (2.9 × 10(-8) M for arthritic sheep vs. 8.6 × 10(-9) M for controls). Digital arteries from arthritic sheep also exhibited a significantly greater EC50 for relaxation to ADP and a significant decrease in the carbachol maximal response. Responses to sodium nitroprusside were unchanged in both coronary and digital arteries.

CONCLUSION

Sheep with RA demonstrated attenuated arterial relaxation to endothelium-dependent vasodilators. This may provide a useful model of endothelial dysfunction in chronic inflammatory conditions. The dysfunction did not appear to be associated with one specific G-protein signalling pathway.

Effect of Curcuma zedoaria Rosc root extracts on behavioral and radiology changes in arthritic rats

The present study was conducted to evaluate the effects of petroleum ether, chloroform, and methanol root extracts of Curcuma zedoaria Rosc (Family: Zingiberaceae) on behavioral and radiology aspects of Freund's Complete Adjuvant (FCA)-induced monoarthritis in left ankle joint of rats using open-field test. Traditionally, Curcuma zedoaria root has been used as anti-inflammatory and antiarthritic drug. Behavioral aspects include latency time to explore, ambulatory, rearing, grooming, urination, and defecation. Animals were divided into ten groups each of six rats, all the animals were subjected to open-field test before the induction of arthritis at 0 day and thereafter 3, 7, 14 21, 28, 35, and 42 days of postinoculation FCA injection. The rat was placed in an open field and observed all behavioral aspects for 5 minutes and radiography analysis was made on day 42. Selected doses were 10 mg/kg.i.p. Indomethacin 200 mg/kg.p.o. marketed herbal drug Rumalaya forte and 200 and 400 mg/kg.p.o. of each extracts, respectively. The results showed significant decrease in ambulation and rearing; however, increase in latency time to explore and grooming, urination, and defecation in control group, but in contrast, drug-treated groups showed significant recovery in all behavioral aspects except methanol groups. On the basis of radiography examination, control and methanol groups showed highest swelling compared with normal group; however, all drug-treated groups showed significant reduced swelling. Treatments with petroleum ether and chloroform extracts recovery were observed in behavioral and radiological aspects in arthritic rats.

Incadronate disodium inhibits joint destruction and periarticular bone loss only in the early phase of rat adjuvant-induced arthritis

Destruction of articular cartilage and subchondral bone loss in the affected joints of rat adjuvant arthritis have never been quantified histologically. This study aimed to evaluate the effect of incadronate disodium on joint destruction and periarticular bone loss, using histomorphometric measurements. Seven-week-old female Lewis rats were injected with 0.1 mg of heat-killed Mycobacterium butyricum into the tail base. Immediately after sensitization, vehicle, or incadronate at 10 or 100 microg/kg per day, was administered subcutaneously, three times per week. Hind-paw volume was measured weekly and the animals were killed at 2, 4, 6, and 10 weeks after sensitization. After taking X-rays, decalcified sagittal sections of the ankle joint were prepared and stained with toluidine blue and tartarate-resistant acid phosphatase. Articular cartilage destruction and subchondral bone loss were evaluated histomorphometrically. At 2 weeks after sensitization, no radiographic or histologic changes were observed. However, at 4 weeks, severe articular cartilage destruction and subchondral bone loss were found in the arthritic control group, while these changes were inhibited dose-dependently by incadronate treatment. At 6 and 10 weeks, both the destructive changes and the bone loss had further progressed, and they were not inhibited by incadronate treatment. Incadronate dose-dependently inhibited articular cartilage destruction and subchondral bone loss at 4 weeks after sensitization in this adjuvant arthritis model. However, the suppressive effects of incadronate did not continue until 6 and 10 weeks.

Synthesis of cetyl myristoleate and evaluation of its therapeutic efficacy in a murine model of collagen-induced arthritis

Cetyl myristoleate (CM) was reported by Diehl and May [J Pharm Sci 83 (1994) 296] to block inflammation and prevent adjuvant-induced arthritis in rats. To verify this earlier work, we have synthesized pure CM and tested its anti-arthritic properties in a collagen-induced arthritis model in DBA/1LacJ mice. Multiple intraperitoneal injections of CM in 450 and 900 mg kg(-1) doses resulted in a significantly lower incidence of disease and caused a modest but significant diminution in clinical signs in those mice that developed arthritis. CM administered in daily oral doses of 20 mg kg(-1) also reduced the incidence of arthritis and caused a small reduction in the clinical signs in mice that developed arthritis. Although the protective effect of CM in collagen-induced arthritis observed in the present study was less dramatic than that reported earlier, our results confirm the anti-arthritic properties of pure CM.

A new spin on an old model: in vivo evaluation of disease progression by magnetic resonance imaging with respect to standard inflammatory parameters and histopathology in the adjuvant arthritic rat

OBJECTIVE

To noninvasively examine the pathogenesis of rat adjuvant-induced arthritis (AIA) by magnetic resonance imaging (MRI), and to correlate MRI indices of disease progression with classic inflammatory parameters and histologic evaluation.

METHODS

AIA was established in male Lewis rats following subcutaneous injection in the right hindpaw with 0.5 mg of heat-killed Mycobacterium butyricum suspended in light mineral oil. In vivo MRI evaluations of soft tissue and bony changes in AIA rats with matched histopathology were correlated with changes in left hindpaw volumes, circulating leukocytes, acute-phase reactants, and urinary collagen crosslinks throughout the disease process.

RESULTS

MRI of arthritic tibiotarsal joints of the uninjected left hindpaws from AIA rats demonstrated 2 distinct phases of disease activity. The first phase, apparent between days 10 and 18, was characterized by periarticular inflammation with marked synovitis, synovial fibroplasia, and distension of the joint capsule into the surrounding tissue. The secondary phase, occurring between days 18 and 30, was marked by continued soft tissue inflammation, periostitis with osteolysis, and periosteal new bone formation progressing to a state of near complete ankylosis by day 30. These 2 phases of disease activity observed by MRI paralleled biochemical, cellular, and histologic markers of disease progression.

CONCLUSION

MRI can be used to noninvasively detect, monitor, and quantify the chronic synovitis and progressive destruction of soft tissue and bone in live AIA rats, thereby improving the ability to evaluate disease progression in this preclinical animal model of rheumatoid arthritis.

Efficacy of sustained blood levels of interleukin-1 receptor antagonist in animal models of arthritis: comparison of efficacy in animal models with human clinical data

OBJECTIVE

To determine the role of interleukin-1 receptor antagonist (IL-1Ra) in rat adjuvant arthritis and rat type II collagen-induced arthritis, and to compare the efficacy in rat models with that seen in human clinical trials of IL-1Ra.

METHODS

Rats with developing adjuvant arthritis or established collagen-induced arthritis were treated with IL-1Ra by continuous infusion in order to determine and maintain efficacious blood levels of this IL-1 inhibitory protein in the rats for comparison with human clinical data. The effects of treatment in the rats were monitored by sequential caliper measurement of the ankle joints, determination of final paw weights, and histologic evaluation with particular emphasis on bone and cartilage lesions. The effects of IL-1Ra on joint swelling and radiographic bone damage in patients with rheumatoid arthritis (RA) in a 6-month trial were compared with the findings in rats.

RESULTS

Dramatic differences in the profile of IL-1Ra activity were seen between the 2 groups of rats. Modest antiinflammatory effects were observed in the adjuvant arthritis rats treated with IL-1Ra. However, marked inhibition of bone resorption occurred, even at doses with which antiinflammatory activity was not seen. In contrast, IL-1Ra treatment of rats with established collagen-induced arthritis resulted in nearly complete suppression of all aspects of the disease when adequate blood levels of IL-1Ra were maintained. Treatment of RA patients with IL-1Ra (150 mg daily) resulted in modest inhibition of joint swelling and inhibition of radiographic progression of bone lesions.

CONCLUSION

IL-1 appears to be of major importance in mediating the bone resorption that occurs in rat adjuvant arthritis, but is less important in the pathogenesis of periarticular inflammation in this disease. In contrast, IL-1 is of major importance in mediating all aspects of disease progression in rat collagen-induced arthritis. Similar to the response in adjuvant arthritic rats, RA patients treated with IL-1Ra showed only modest antiinflammatory activity, but had evidence of inhibition of progression of bone resorption. However, a comparison of the plasma levels of IL-1Ra in humans and rats suggests that the optimal level of dosing for continuous saturation of IL-1 receptors may not have been achieved in humans, although this was achieved in the rat studies.

Animal models of arthritis: relevance to human disease

Animal models of arthritis are used to evaluate potential antiarthritis drugs for clinical use. Therefore capacity of the model to predict efficacy in human disease is one of the most important criteria in model selection. Animal models of rheumatoid arthritis (RA) with a proven track record of predictability include rat adjuvant arthritis, rat type II collagen arthritis, mouse type II collagen arthritis, and antigen-induced arthritis in several species. Agents currently in clinical use (or trials) that are active in these models include corticosteroids, methotrexate, nonsteroidal anti-inflammatory drugs, cyclosporin A, leflunomide, interleukin-1 receptor antagonist, and soluble tumor necrosis factor receptors. For some of these agents, the models also predict that toxicities seen at higher doses for prolonged periods would preclude dosing in humans at levels that might provide disease-modifying effects. Animal models of osteoarthritis (OA) include mouse and guinea pig spontaneous OA, meniscectomy and ligament transection in guinea pigs, meniscectomy in rabbits, and meniscectomy and cruciate transection in dogs. None of these models have a proven track record of predictability in human disease because there are no agents that have been proven to provide anything other than symptomatic relief in human OA. Efficacy data and features of the various models of RA and OA are discussed with emphasis on their proven relevance to human disease.

Meloxicam: a potent inhibitor of adjuvant arthritis in the Lewis rat

The effects of meloxicam, piroxicam, diclofenac and tenidap on the swelling of hind paws, radiologically-detectable bone and cartilage destruction of hind paws, increase in spleen weight, increase in erythrocyte sedimentation rate and changes in serum protein composition in male Lewis rats with adjuvant arthritis were studied following once-daily oral administration of these drugs for 21 days. All the drugs dose-dependently inhibited hind paw swelling. For equal activity against hind paw swelling caused by the secondary reaction, the required daily dose of piroxicam was about twice that of meloxicam; those of diclofenac and tenidap were about 3.5 and 60 times higher respectively. The bone and cartilage destruction induced by adjuvant arthritis were inhibited by meloxicam at low daily doses and by piroxicam at doses approximately four times those of meloxicam. Diclofenac and tenidap had only a weak effect on radiologically-detectable lesions when administered at doses sufficient to reduce paw swelling. Meloxicam also had a dose-dependent corrective effect on the systemic changes which occur in adjuvant arthritic rats, e.g. increase in spleen weight, increase in erythrocyte sedimentation rate and changes in serum protein composition. Piroxicam produced similar effects, at 3-4 times higher doses. Diclofenac and tenidap did not show comparable effects when administered at appropriate doses. These findings indicate that the action of meloxicam and piroxicam differs from that of diclofenac and tenidap in adjuvant arthritis in the Lewis rat. At oral doses which significantly reduce edema formation, only meloxicam and piroxicam showed a significant effect on systemic parameters of adjuvant disease in the Lewis rat.

Effects of gold sodium thiomalate, cyclosporin A, cyclophosphamide, and placebo on collagen-induced arthritis in rats

The prophylactic and therapeutic effects of gold sodium thiomalate, cyclosporin A, cyclophosphamide, and placebo on collagen-induced arthritis (CIA) were evaluated in DA rats. Prophylactic treatment with cyclosporin A and cyclophosphamide suppressed the arthritis incidence, clinical inflammation, destructive bone changes, and development of anti-collagen antibody in DA rats subsequently injected with porcine type-II collagen. Therapeutic treatment with cyclosporin A and cyclophosphamide had a definite suppression on established CIA when started 21 days after the initial collagen injection, but the suppression was less marked than that of prophylactic treatment. Gold had no impact on CIA in DA rats when administered either prophylactically or therapeutically.

Adjuvant-induced arthritis in rats. Evidence that autoimmunity to homologous collagens types I, II, IX and XI is not involved in the pathogenesis of arthritis

We examined the sera of arthritic outbred Wistar and Sprague-Dawley rats and inbred Fisher 344 and Wistar-Lewis rats for autoantibodies to rat type I, II, IX and XI collagens following the induction of arthritis with mycobacteria (MTB). Although many sera collected over an extended time were assayed in addition to acid eluates of arthritic joints, convincing evidence for autoimmunity to collagen could not be demonstrated. Instead, modest non-specific reactions were observed to collagen, irrelevant proteins, and buffer-treated plastic microtitre wells. In contrast, antibodies to purified protein derivative (PPD) were detected in the sera of rats developing adjuvant-induced arthritis, and antibodies to type II collagen, in the sera and joint eluate of rats developing experimental collagen-induced arthritis. Lastly, delayed-type hypersensitivity responses to collagen could not be detected, nor could adjuvant-induced arthritis be attenuated by soluble collagen injected intravenously before challenge with MTB. We conclude that adjuvant-induced arthritis and experimental collagen-induced arthritis are distinct models of rheumatic disease and that autoimmunity to collagen is neither prevalent in adjuvant-induced arthritis nor necessary for its pathogenesis.

Macrophages and dendritic cells during the early stages of antigen-induced arthritis in rats: immunohistochemical analysis of cryostat sections of the whole knee joint

The appearance of different macrophage subpopulations, Ia-positive antigen-presenting dendritic cells and of T and B lymphocytes was studied in early phases of antigen-induced arthritis in rat knee joints. Cryostat sections of whole knee joints were analysed with immunohistochemical techniques using monoclonal antibodies against rat macrophages, Ia-antigen, and lymphocyte subpopulations. The results showed that in the early phases of the development of arthritis, the synovium was already infiltrated by many monocytes, young macrophages, granulocytes, perivascular Ia-positive non-lymphoid cells, some mature tissue macrophages, and only few T lymphocytes. In later phases not only monocytes, young macrophages and Ia-positive cells became more prominent but also the more mature ED2 positive macrophages and the ED3 positive macrophages that are normally confined to lymphoid organs became increasingly important. The T-cell population increased to some extent in later phases of arthritis induction, possibly induced by clustering with the Ia-positive cells.

Bone changes in rats with adjuvant arthritis: treatment with 1 alpha-hydroxycholecalciferol

Adjuvant arthritis was induced in female Lewis rats by the injection of Mycobacterium butyricum in mineral oil in a hindpaw. Bone changes due to polyarthritis were evaluated in the tibia metaphyseal region of the noninjected hind leg. A decrease in bone mass and mineral content was observed in the affected bone. accompanied by a marked increase in bone resorption. Non-arthritic and arthritic rats were treated with the synthetic vitamin D analogue, 1 alpha-hydroxycholecalciferol (0.01 to 1.0 micrograms/kg/day orally) for 28 days. Treatment resulted in a small increase in bone weight and mineral content in the non-arthritic rats. Arthritic rats exhibited a larger increase in bone weight, hydroxyproline and calcium content. These beneficial effects were correlated with the ability of 1 alpha-hydroxycholecalciferol to increase extracellular calcium and phosphorus levels, as measured by the increased urinary excretion of calcium and inorganic phosphate and by the increase in serum calcium. Bone resorption and new bone formation were not affected by the treatment.