Antarctic Krill Oil Ameliorates Monosodium Iodoacetate-Induced Irregularities in Articular Cartilage and Inflammatory Response in the Rat Models of Osteoarthritis.

The aim of this study was to examine the effects of Antarctic krill oil (FJH-KO) in a rat model of monosodium iodoacetate (MIA) induced osteoarthritis. The effect of FJH-KO on the development and severity of MIA-induced osteoarthritis was assessed using hematoxylin and eosin (H&E) staining and micro-CT. The expression of PGE2, pro-inflammatory cytokines (IL-1ß, TNF-α), and arthritics related genes in osteoarthritic rats in response to FJH-KO supplementation was investigated using real time PCR. FJH-KO supplementation in the arthritic rat model reduced tissue damage, cartilage degeneration, and reduced the MIA-induced irregularities in articular cartilage surface. Serum PGE2, IL-1ß, IL-6, and TNF-α levels were higher in MIA treated animals, but these levels decreased upon FJH-KO supplementation. When FJH-KO was provided at a dose of 150 mg/kg b.w to MIA-treated animals, it significantly increased the mRNA expression of anabolic factors. The mRNA expression of catabolic factors was significantly decreased MIA-treated animals that were provided FJH-KO at a dose of 100 and 150 mg/kg b.w. Moreover, the mRNA expression of inflammatory mediators was significantly decreased MIA-treated animals supplemented with FJH-KO. These results suggest supplementation with FJH-KO ameliorates the irregularities in articular cartilage surface and improves the inflammatory response in the osteoarthritis. Thus, FJH-KO could serve as a potential therapeutic agent for osteoarthritis treatment.

Daphne mucronata enhances cell proliferation and protects human adipose stem cells against monosodium iodoacetate induced oxidative stress in vitro.

Mesenchymal stem cells (MSCs) are being used to treat many diseases as they exhibit great regenerative potential. However, MSC's transplantation sometimes does not yield the maximum regenerative outcome as they are unable to survive in inflammatory conditions. Several approaches including preconditioning are used to improve the survival rate of mesenchymal stem cells. One such recently reported approach is preconditioning MSCs with plant extracts. The present study was designed to evaluate the effect of Daphne mucronata extract on stressed human adipose-derived mesenchymal stem cells (hADMSCs). Isolated hADMSCs were preconditioned with different concentrations of Daphne muconata extract and the protective, proliferative, antioxidant and anti-inflammatory effect was assessed through various assays and expression analysis of inflammatory markers regulated through NF-κB pathway. Results suggest that preconditioning hADMSCs with Daphne mucronata increased the cell viability, proliferative and protective potential of hADMSCs with a concomitant reduction in LDH, ROS and elevation in SOD activity. Moreover, both the ELISA and gene expression analysis demonstrated down regulations of inflammatory markers (IL1-ß, TNF-α, p65, p50, MMP13) in Daphne mucronata preconditioned hADMSCs as compared to stress. This is the first study to report the use of MIA induced oxidative stress against hADMSC's and effect of Daphne mucronata on stressed hADMSCs. Results of these studies provided evidence that Daphne mucronata protects the hADMSCs during stress conditions by down regulating the inflammatory markers and hence increase the viability and proliferative potential of hADMSCs that is crucial for transplantation purposes.

Manjarix attenuated pain and joint swelling in a rat model of monosodium iodoacetate-induced osteoarthritis.

Osteoarthritis (OA) is a joint disease characterized by degeneration of cartilage, intra-articular inflammation, remodeling of subchondral bone and joint pain. The present study was designed to assess the therapeutic effects and the possible underlying mechanism of action of Manjarix, a herbal combination composed of ginger and turmeric powder extracts, on chemically induced osteoarthritis in rats. An OA model was generated by intra-articular injection of 50 µL (40 mg mL-1) of monosodium iodoacetate (MIA) into the right knee joint of rats. After one week of osteoarthritis induction, a comparison of the anti-inflammatory efficacy of indomethacin at an oral dose of 2 mg kg-1 daily for 4 successive weeks versus five decremental dose levels of Manjarix (1000, 500, 250, 125, and 62.5 mg kg-1) was performed. Serum inflammatory cytokines, interleukin 6, interleukin 8, and tumor necrosis factor alpha; C-telopeptide of type II collagen (CTX-II) and hyaluronic acid (HA) were measured, along with weekly assessment of the knee joint swelling. Pain-like behavior was assessed and knee radiographic and histological examination were performed to understand the extent of pain due to cartilage degradation. Manjarix significantly reduced the knee joint swelling, decreased the serum levels of IL6, TNF-α, CTX-II and HA, and reduced the pathological injury in joints, with no evidence of osteo-reactivity in the radiographic examination. Manjarix also significantly prevented MIA-induced pain behavior. These results demonstrate that Manjarix exhibits chondroprotective effects and can inhibit the OA pain induced by MIA, and thus it can be used as a potential therapeutic product for OA.

FlexPro MD®, a Combination of Krill Oil, Astaxanthin and Hyaluronic Acid, Reduces Pain Behavior and Inhibits Inflammatory Response in Monosodium Iodoacetate-Induced Osteoarthritis in Rats.

Osteoarthritis (OA) is a degenerative joint disease and a leading cause of adult disability. Since there is no cure for OA and no effective treatment to slow its progression, current pharmacologic treatments, such as analgesics and non-steroidal anti-inflammatory drugs (NSAIDs), only alleviate symptoms, such as pain and inflammation, but do not inhibit the disease process. Moreover, chronic intake of these drugs may result in severe adverse effects. For these reasons, patients have turned to the use of various complementary and alternative approaches, including diverse dietary supplements and nutraceuticals, in an effort to improve symptoms and manage or slow disease progression. The present study was conducted to evaluate the anti-osteoarthritic effects of FlexPro MD® (a mixture of krill oil, astaxanthin, and hyaluronic acid; FP-MD) in a rat model of OA induced by monosodium iodoacetate (MIA). FP-MD significantly ameliorated joint pain and decreased the severity of articular cartilage destruction in rats that received oral supplementation for 7 days prior to MIA administration and for 21 days thereafter. Furthermore, FP-MD treatment significantly reduced serum levels of the articular cartilage degeneration biomarkers cartilage oligomeric matrix protein (COMP) and crosslinked C-telopeptide of type II collagen (CTX-II), and the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6), as well as mRNA expression levels of inflammatory mediators, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and matrix-degrading enzymes, matrix metalloproteinase (MMP)-2 and MMP-9, in the knee joint tissue. Our findings suggest that FP-MD is a promising dietary supplement for reducing pain, minimizing cartilage damage, and improving functional status in OA, without the disadvantages of previous dietary supplements and medicinal agents, including multiple adverse effects.

Effects of ID-CBT5101 in Preventing and Alleviating Osteoarthritis Symptoms in a Monosodium Iodoacetate-Induced Rat Model.

Osteoarthritis is a disease that affects the articular cartilage and osseous tissue, and can be worsened by aging, overweight status, and post-traumatic arthritis. The present study aimed to evaluate the effect of ID-CBT5101 (tyndallized Clostridium butyricum) on bone metabolism and the inflammatory response in a monosodium iodoacetate-induced rat model of osteoarthritis. ID-CBT5101 was administered orally at doses of 108 or 1010 CFU/day for 2 weeks before direct injection of monosodium iodoacetate (3 mg/50 µl of 0.9% saline) into the intra-articular space of the rats' right knees. The rats subsequently received the same doses of oral ID-CBT5101 for another 4 weeks. We evaluated the treatment effects based on serum biomarkers, mRNA expression, morphological and histopathological analyses of the knee joints, and weight-bearing distribution analysis. Compared with those in control rats, the ID-CBT5101 treatments significantly reduced the serum concentration of inflammation and bone metabolism markers (i.e., COX-2, IL-6, LTB4, and COMP), and significantly increased the concentration of IFN-γ and glycosaminoglycans. In addition, the ID-CBT5101 treatments inhibited the mRNA expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases (i.e., MMP-2, MMP-3, MMP-9, MMP-13, TIMP-1, and TIMP-2). Furthermore, the ID-CBT5101 treatments effectively preserved the knee cartilage and synovial membrane, and significantly decreased the amount of fibrous tissue. Moreover, compared with that of the negative control group, the ID-CBT5101 treatments increased the weight-bearing distribution by ≥20%. The results indicate that ID-CBT5101 prevented and alleviated osteoarthritis symptoms. Thus, ID-CBT5101 may be a novel therapeutic option for the management of osteoarthritis.

Chondroitin sulfate from sturgeon bone ameliorates pain of osteoarthritis induced by monosodium iodoacetate in rats.

Chondroitin sulfate (CS) is an important component of the extracellular matrix of cartilage and has been widely used as one of the main drugs for the treatment of joint pain-related nutraceuticals and medicines. Sturgeon bone (SB) is the main waste during deep processing of sturgeons in fishery production. The present study was evaluated the therapeutic effect of CS from SB (CSSB) on monosodium iodoacetate (MIA)-induced osteoarthritis (OA) pain and further explored the potential medicinal value of CSSB. The OA pain model was induced by intra-articular injection of MIA and then treated with CSSB. The results showed that, on the organismic level, CSSB can significantly reduce the joint swelling, reduce the pathological injury of the joints, decrease the levels of IL-1, TNF-α and PGE2 in synovial fluid, revers of hind paw support and paw withdrawal mechanical threshold decreased caused by MIA. In addition, mechanistically at the molecular level, these effects are elicited via down-regulation of the protein levels of down-regulate the protein expression of matrix metalloproteinase (MMP)-1, MMP-13 and up-regulate the protein expression of TIMP-1. These results demonstrate that CSSB can inhibit the OA pain induced by MIA, and CSSB can be used as a potential medicinal ingredient.

Spinacia oleracea extract attenuates disease progression and sub-chondral bone changes in monosodium iodoacetate-induced osteoarthritis in rats.

BACKGROUND: Spinacia oleracea is an important dietary vegetable in India and throughout the world and has many beneficial effects. It is cultivated globally. However, its effect on osteoarthritis that mainly targets the cartilage cells remains unknown. In this study we aimed to evaluate the anti-osteoarthritic and chondro-protective effects of SOE on chemically induced osteoarthritis (OA). METHODS: OA was induced by intra-patellar injection of monosodium iodoacetate (MIA) at the knee joint in rats. SOE was then given orally at 250 and 500 mg.kg- 1 day- 1 doses for 28 days to these rats. Anti-osteoarthritic potential of SOE was evaluated by micro-CT, mRNA and protein expression of pro-inflammatory and chondrogenic genes, clinically relevant biomarker's and behavioural experiments. RESULTS: In vitro cell free and cell based assays indicated that SOE acts as a strong anti-oxidant and an anti-inflammatory agent. Histological analysis of knee joints at the end of the experiment by safranin-o and toluidine blue staining established its protective effect. Radiological data corroborated the findings with improvement in the joint space and irregularity of the articular and atrophied femoral condyles and tibial plateau. Micro-CT analysis of sub-chondral bone indicated that SOE had the ability to mitigate OA effects by increasing bone volume to tissue volume (BV/TV) which resulted in decrease of trabecular pattern factor (Tb.Pf) by more than 200%. SOE stimulated chondrogenic marker gene expression with reduction in pro-inflammatory markers. Purified compounds isolated from SOE exhibited increased Sox-9 and Col-II protein expression in articular chondrocytes. Serum and urine analysis indicated that SOE had the potential to down-regulate glutathione S-transferase (GST) activity, clinical markers of osteoarthritis like cartilage oligometric matrix protein (COMP) and CTX-II. Overall, this led to a significant improvement in locomotion and balancing activity in rats as assessed by Open-field and Rota rod test. CONCLUSION: On the basis of in vitro and in vivo experiments performed with Spinacea oleracea extract we can deduce that SOE has the ability to alleviate the MIA induced deleterious effects.

Phenotypic alterations of neurons that innervate osteoarthritic joints in rats.

OBJECTIVE: Pain is a prominent feature of osteoarthritis (OA). To further understand the primary mechanisms of nociception in OA, we studied the expression of the phenotype markers calcitonin gene-related peptide (CGRP), isolectin B4 (IB4), and neurofilament 200 (NF200) in sensory neurons innervating the OA knee joint in rats. METHODS: OA was induced in rats by intraarticular injection of 2 mg of mono-iodoacetate (MIA) into the knee. Neurons innervating the joint were identified by retrograde labeling with fluorogold in dorsal root ganglia (DRG) and colocalized with neurochemical markers by immunofluorescence. The total number of DRG cells was determined by stereologic methods in Nissl-stained sections. RESULTS: A 37% decrease in the number of fluorogold-backlabeled cells was observed in rats with OA when compared with control rats, even though no decrease in the total number of cells was observed. However, an increase in the number of medium/large cell bodies and a decrease in the number of the smallest cells were observed, suggesting the occurrence of perikarya hypertrophy. The percentage of CGRP-positive cells increased significantly, predominantly in medium/large cells, suggesting the occurrence of a phenotypic switch. Colocalization of CGRP and NF200 revealed no significant changes in the percentage of double-labeled cells, but an increase in the number of medium/large double-labeled cells was observed. No differences in the expression of either IB4 or NF200 were observed in fluorogold-backlabeled cells. CONCLUSION: These results indicate that MIA-induced OA causes an up-regulation of CGRP in different subpopulations of primary afferent neurons in DRG due to a phenotypic switch and/or cell hypertrophy which may be functionally relevant in terms of the onset of pain in this pathologic condition.

Tonic modulation of spinal hyperexcitability by the endocannabinoid receptor system in a rat model of osteoarthritis pain.

OBJECTIVE: To investigate the impact of an experimental model of osteoarthritis (OA) on spinal nociceptive processing and the role of the inhibitory endocannabinoid system in regulating sensory processing at the spinal level. METHODS: Experimental OA was induced in rats by intraarticular injection of sodium mono-iodoacetate (MIA), and the development of pain behavior was assessed. Extracellular single-unit recordings of wide dynamic range (WDR) neurons in the dorsal horn were obtained in MIA-treated rats and saline-treated rats. The levels of endocannabinoids and the protein and messenger RNA levels of the main synthetic enzymes for the endocannabinoids (N-acyl phosphatidylethanolamine phospholipase D [NAPE-PLD] and diacylglycerol lipase α [DAGLα]) in the spinal cord were measured. RESULTS: Low-weight (10 gm) mechanically evoked responses of WDR neurons were significantly (P < 0.05) facilitated 28 days after MIA injection compared with the responses in saline-treated rats, and spinal cord levels of anandamide and 2-arachidonoyl glycerol (2-AG) were increased in MIA-treated rats. Protein levels of NAPE-PLD and DAGLα, which synthesize anandamide and 2-AG, respectively, were elevated in the spinal cords of MIA-treated rats. The functional role of endocannabinoids in the spinal cords of MIA-treated rats was increased via activation of cannabinoid 1 (CB(1) ) and CB(2) receptors, and blockade of the catabolism of anandamide had significantly greater inhibitory effects in MIA-treated rats compared with control rats. CONCLUSION: Our findings provide new evidence for altered spinal nociceptive processing indicative of central sensitization and for adaptive changes in the spinal cord endocannabinoid system in an experimental model of OA. The novel control of spinal cord neuronal responses by spinal cord CB(2) receptors suggests that this receptor system may be an important target for the modulation of pain in OA.

Decrease in oxidative stress and histological changes induced by physical exercise calibrated in rats with osteoarthritis induced by monosodium iodoacetate.

OBJECTIVE: The purpose of this study was to evaluate the effects of impact exercise on the joint cartilage of rats with osteoarthritis (OA) induced by monosodium iodoacetate (MIA). METHODS: Eighteen male rats were divided into three groups of six animals each: control, OA, and OA plus exercise (OAE). The OAE group trained on a treadmill for 8 weeks. Afterward, the right joints of the animals were washed with saline solution and joint lavage was used for biochemical analyses of myeloperoxidase (MPO) and enzyme superoxide dismutase (SOD) activities and total thiol content. The same limb provided samples of the articular capsule for analyses of MPO activity and total thiol content. The left joint was used for histological analysis. RESULTS: Our results indicate that MPO activity was increased in both OA groups in the lavage as well as the articular capsule, regardless of exercise status. SOD activity was increased in animals with OA, especially in the animals that had run on the treadmill. On the other hand, thiol content in the articular capsule and joint lavage decreased in the OA group, while the OAE group had values similar to those of the control group. The histological data indicate that animals that were submitted to running exercise showed a higher preservation rate of proteoglycan content in the superficial and intermediate areas of the joint cartilage. CONCLUSION: Our results show that physical training contributes to the preservation of joint cartilage in animals with OA and to increase the defense mechanism against oxidative stress.

Chondroprotective effects of pomegranate juice on monoiodoacetate-induced osteoarthritis of the knee joint of mice.

To study the effectiveness of pomegranate juice on osteoarthritis, mono-iodoacetate induced loss of articular cartilage in the mouse tibiofemoral joint was used as a model. Mono-iodoacetate is an inhibitor of glycolysis which promotes osteoarthritis similar to that noted in human osteoarthritis. The histopathology of the subchondral bone and cartilage of mouse knee joints treated with a single intra-articular injection of mono-iodoacetate (0.1 mg) and killed at 1, 14 and 28 days post injection was investigated. The effect of pomegranate juice (4 mL/kg, 10 mL/kg, 20 mL/kg, orally) was studied in different groups. Histopathological changes in knee joints were seen after 2 weeks. Early osteoarthritis was characterized by areas of chondrocyte degeneration, which sometimes involved the entire thickness of the articular cartilage in the tibial plateaus and femoral condyles. Changes to the subchondral bone and proteoglycan contents, focal fragmentation and collapse of bony trabeculae with fibrosis and necrosis, and synovial cell proliferation were observed. The administration of pomegranate juice dose dependently prevented the negative effects of iodoacetate. Chondrocyte damage was significantly prevented, with proteoglycan less affected, especially in the groups receiving a high amount of pomegranate juice. No cell proliferation or inflammatory cells were detected in the synovial fluid. The effectiveness of pomegranate juice in improving histopathological damage is emphasized and its chondroprotective effect in vivo highlighted.

Induction of an antiinflammatory effect and prevention of cartilage damage in rat knee osteoarthritis by CF101 treatment.

OBJECTIVE: Studies have suggested that rheumatoid arthritis (RA) and osteoarthritis (OA) share common characteristics. The highly selective A(3) adenosine receptor agonist CF101 was recently defined as a potent antiinflammatory agent for the treatment of RA. The purpose of this study was to examine the effects of CF101 on the clinical and pathologic manifestations of OA in an experimental animal model. METHODS: OA was induced in rats by monosodium iodoacetate, and upon disease onset, oral treatment with CF101 (100 microg/kg given twice daily) was initiated. The A(3) adenosine receptor antagonist MRS1220 (100 microg/kg given twice daily) was administered orally, 30 minutes before CF101 treatment. The OA clinical score was monitored by knee diameter measurements and by radiographic analyses. Histologic analyses were performed following staining with hematoxylin and eosin, Safranin O-fast green, or toluidine blue, and histologic changes were scored according to a modified Mankin system. Signaling proteins were assayed by Western blotting; apoptosis was detected via immunohistochemistry and TUNEL analyses. RESULTS: CF101 induced a marked decrease in knee diameter and improved the changes noted on radiographs. Administration of MRS1220 counteracted the effects of CF101. CF101 prevented cartilage damage, osteoclast/osteophyte formation, and bone destruction. In addition, CF101 markedly reduced pannus formation and lymphocyte infiltration. Mechanistically, CF101 induced deregulation of the NF-kappaB signaling pathway, resulting in down-regulation of tumor necrosis factor alpha. Consequently, CF101 induced apoptosis of inflammatory cells that had infiltrated the knee joints; however, it prevented apoptosis of chondrocytes. CONCLUSION: CF101 deregulated the NF-kappaB signaling pathway involved in the pathogenesis of OA. CF101 induced apoptosis of inflammatory cells and acted as a cartilage protective agent, which suggests that it would be a suitable candidate drug for the treatment of OA.

Grading of monosodium iodoacetate-induced osteoarthritis reveals a concentration-dependent sensitization of nociceptors in the knee joint of the rat.

Osteoarthritis (OA) is a degenerative joint disease characterized by joint pain for which there is currently no effective treatment. Previous studies have found that intra-articular injection of monosodium iodoacetate (MIA) caused a dose-dependent destruction of rat knees with concomitant increased pain. In this study, varying degrees of OA were induced by intra-articular injection of 0.1 mg, 0.3 mg and 3 mg MIA. Electrophysiological recordings were made from knee joint primary afferents in response to rotation of the joint and firing frequencies were determined and compared to saline-injected control joints. The analgesic effect of local application of the classic non-steroidal anti-inflammatory drug (NSAID) diclofenac (0.1 mg/0.1 ml bolus) was also determined in each group. Joint afferent firing frequency was significantly enhanced in OA knees compared to saline injected control joints and the magnitude of this sensitization showed a direct relationship with increasing dose of MIA. Diclofenac reduced nociception significantly in the 3 mg MIA treated joint, but had no effect on nerve mechanosensitivity in rats with milder OA. This study shows for the first time that MIA produces a graded sensitization of joint nociceptors making this a useful model for the study of pain mechanisms in joints with progressive OA severity. The anti-nociceptive effect of diclofenac further indicates that the MIA model offers an attractive means of objectively testing potential therapeutic agents.

Liposomal dexamethasone-diclofenac combinations for local osteoarthritis treatment.

Conventional chronic and acute treatments for osteoarthritis (OA) are by oral NSAIDs (such as diclofenac) and intra-articular injected glucocorticosteroids (such as dexamethasone). In free form, diclofenac and dexamethasone generate severe adverse effects with risks of toxicity. To reduce these drawbacks, we investigated local injections of liposomal formulations for diclofenac and dexamethasone (each alone, and their combination). Bioadhesive liposomes carrying hyaluronan (HA-BAL) or collagen (COL-BAL) as their surface-anchored ligand were used for the task. Each drug alone or their combination showed high efficiency encapsulations (> or =80%) and performance as slow-release depots (half-lives in the range of 1-3 days under the fastest conditions). Employing RIA and immunoblot assay techniques, it was verified that the encapsulated drugs retained their biological activities: inhibitions of Cyclooxygenases enzyme-activity (diclofenac) and of Cyclooxygenases protein-expression (dexamethasone). Using live-animal MRI, a single intra-articular injection of each liposome-drug(s) formulation sufficed to reduce knee joint inflammation in OA rats over a time span of 17 days, HA-BAL better than COL-BAL. The most effective treatment was by the combination of both drugs in HA-BAL, a single dose reducing the inflammation volume down to 12.9% from initial over that time span. We find all three HA-BAL formulations worthy of further studies.

Validation of a chemical osteoarthritis model in rabbit temporomandibular joint: a compliment to biomechanical models.

To explore degenerative mechanisms occurring in the temporomandibular joint (TMJ), a chemical model of knee joint osteoarthritis using sodium mono-iodoacetate injection was transposed to the TMJ. Twelve New Zealand rabbits were used to document the effect of this drug on the TMJ. Eight rabbits underwent bilateral iodoacetate injection in the disco-condylar compartment while 4 served as controls. Rabbits were sacrificed at 10, 20, 30 and 40 days and joints studied by histology. Severity of the damage was time dependent and the use of iodoacetate allowed the observation, within a few weeks, of every osteoarthritic stage usually described in the literature. This study showed that the TMJ has a specific response to the degenerative process. This response was characterized by (i) thickening and fibrillation of the cartilage at the periphery of the lesion, tending to reduce mechanical stress in the lesional area and (ii) chondrocyte migration under areas where subchondral bone surface was locally destroyed. The extracellular matrix containing chondrocyte clusters and prechondrocytes dived around the bony defect and proceeded below the necrotic bone to promote the eviction of bony fragments into the joint cavity, pushing them up while the thickness of chondrocyte rows increased below. This could be interpreted as a repairing attempt due to the specific potential of fibrocartilage proliferative cells.

Acetoacetate protects hippocampal neurons against glutamate-mediated neuronal damage during glycolysis inhibition.

Glucose is the main substrate that fulfills energy brain demands. However, in some circumstances, such as diabetes, starvation, during the suckling period and the ketogenic diet, brain uses the ketone bodies, acetoacetate and beta-hydroxybutyrate, as energy sources. Ketone body utilization in brain depends directly on its blood concentration, which is normally very low, but increases substantially during the conditions mentioned above. Glutamate neurotoxicity has been implicated in neurodegeneration associated with brain ischemia, hypoglycemia and cerebral trauma, conditions related to energy failure, and to elevation of glutamate extracellular levels in brain. In recent years substantial evidence favoring a close relation between glutamate neurotoxic potentiality and cellular energy levels, has been compiled. We have previously demonstrated that accumulation of extracellular glutamate after inhibition of its transporters, induces neuronal death in vivo during energy impairment induced by glycolysis inhibition. In the present study we have assessed the protective potentiality of the ketone body, acetoacetate, against glutamate-mediated neuronal damage in the hippocampus of rats chronically treated with the glycolysis inhibitor, iodoacetate, and in hippocampal cultured neurons exposed to a toxic concentration of iodoacetate. Results show that acetoacetate efficiently protects against glutamate neurotoxicity both in vivo and in vitro probably by a mechanism involving its role as an energy substrate.

Moderation of iodoacetate-induced experimental osteoarthritis in rats by matrix metalloproteinase inhibitors.

OBJECTIVE: To determine the effect of matrix metalloproteinase (MMP) inhibitors in mono-iodoacetate-induced arthritis in rats. DESIGN: The ability of compounds to inhibit MMPs in vitro was assessed kinetically using a quenched fluorescent substrate. Rats were injected with iodoacetate intraarticularly in one knee joint and damage to the tibial plateau was evaluated from digitized images captured using an image analyser and by histology. Collagenase and gelatinase activity in cartilage from iodoacetate injected knees were evaluated using(3)H-rat type I collagen and gelatin zymography, respectively. RESULTS: Collagenase and gelatinase activity significantly increased in the knee cartilage of rats injected with iodoacetate with peak activity by day 7. Three MMP inhibitors were examined for their efficacy in the rat iodoacetate-induced arthritis model. Significant (P< 0.05) inhibition of cartilage damage was observed in animals treated orally with 35 mg/kg b.i.d. of the three different MMP inhibitors. Inhibition of cartilage damage by the MMP inhibitors ranged from 36-42%. CONCLUSION: MMP inhibitors are partially protective against cartilage and subchondral bone damage induced by iodoacetate. These results support an important role for MMPs in mediating the joint damage in this model of arthritis.

An evaluation of chemical arthrodesis of the proximal interphalangeal joint in the horse by using monoiodoacetate.

The use of monoiodoacetate (MIA) for arthrodesis of the proximal interphalangeal joint (PIJ) and the effect of exercise on the degree of fusion were investigated. Eight horses received 3 injections (Weeks 0, 3, 6) of MIA (2 mL; 60 mg/mL) into the right or left front PIJ. Peri-operatively, the horses received phenylbutazone, butorphanol, and abaxial sesamoidean nerve blocks to relieve pain. During the study, the horses were monitored for general health, lameness, and swelling around the injection area. Radiographs were taken biweekly to evaluate bony fusion. Horses were randomly divided into non-exercised and exercised groups. Exercise consisted of 20 minutes of trotting on a treadmill (4 m/s), 3 days per week for 13 weeks. The horses were euthanized at 24 weeks. Slab sections of the PIJ were evaluated grossly and radiographically for bony fusion. Histologic examinations were performed to evaluate articular cartilage. Three horses were excluded from the study after developing soft tissue necrosis around the injection site, septic arthritis, and necrotic tendinitis. The remaining horses remained healthy, developed a grade 1 to 4 lameness with minimal to severe swelling in the PIJ region. All 5 horses showed radiographic evidence of bony fusion, however, no fusion was present when injected joints were examined on postmortem examination. Histologic examination revealed thinning of the cartilage, diffuse necrosis of chondrocytes, with the calcified zone intact. Subjectively, exercise did not influence the degree of cartilage destruction. Based on this study, chemical arthrodesis cannot be advocated in clinical cases because of the high complication rate and lack of bony fusion.

Triamcinolone hexacetonide protects against fibrillation and osteophyte formation following chemically induced articular cartilage damage.

Although corticosteroids have been shown to cause articular cartilage degeneration, recent studies of experimentally induced osteoarthritis indicate that under certain conditions they may protect against cartilage damage and osteophyte formation. The present study examines the in vivo effect of triamcinolone hexacetonide on the degeneration of articular cartilage which occurs following intraarticular injection of sodium iodoacetate. Three weeks after a single injection of iodoacetate into the knees of guinea pigs, ipsilateral femoral condylar cartilage exhibited fibrillation, loss of staining with Safranin O, depletion of chondrocytes, and prominent osteophytes. In striking contrast, when triamcinolone hexacetonide was injected into the ipsilateral knee 24 hours after the intraarticular injection of iodoacetate, fibrillation was noted in only 1 of 6 samples, osteophytes were much less prominent, pericellular staining with Safranin O persisted, and cell loss was less extensive. Knees of animals which received only one-tenth as much intraarticular triamcinolone hexacetonide after the iodoacetate injection also exhibited marked reduction in size and extent of osteophytes. However, the degree of fibrillation, loss of Safranin O staining, and chondrocyte depletion was similar to that observed in animals injected with iodoacetate but not treated with intraarticular steroid. No apparent morphologic or histochemical changes were observed after intraarticular injection of the steroid preparation alone. Thus, triamcinolone hexacetonide produced a marked, dose-dependent protective effect in this model of chemically induced articular cartilage damage.

Immobilization ameliorates chemically-induced articular cartilage damage.

We have previously shown that immobilization protects against the development of mechanically-induced osteoarthritis following-anterior cruciate ligament transection in dogs. Herein, we examine the effect of immobilization of the leg on the chemically-induced degeneration of femoral articular cartilage caused by intraarticular injection of iodoacetate in guinea pigs. One week after the injection, cartilage from animals which were not immobilized exhibited a decrease in Safranin O staining and a 10-20% reduction in the number of chondrocytes. Three weeks after injection, cell death and loss of Safranin O staining had progressed, and surface fibrillation and osteophytes had developed. Articular cartilage from the contralateral (uninjected) knees of guinea pigs which received iodoacetate, and from knees of animals which were immobilized for 1 week but did not receive iodoacetate, was histologically and histochemically normal. However, specimens from 2 of 4 untreated knees which were immobilized for 3 weeks showed a reduction in Safranin O staining. Immobilization of the knee did not alter the loss of Safranin O staining seen after intraarticular iodoacetate injection, but did reduce the depletion of chondrocytes (P less than 0.05). Furthermore, neither osteophytes nor fibrillation developed in any of the animals which were constrained after iodoacetate injection. Thus, immobilization was clearly protective in this model of chemically-induced cartilage injury.