Fermented Lettuce Extract Containing Nitric Oxide Metabolites Attenuates Inflammatory Parameters in Model Mice and in Human Fibroblast-Like Synoviocytes.

Lettuce (Lactuca sativa L.) contains various bioactive compounds that can reduce the severity of inflammatory diseases. This study aimed to identify therapeutic effects and underlying mechanisms of fermented lettuce extract (FLE) containing stable nitric oxide (NO) on collagen-induced arthritis (CIA) in mice and fibroblast-like synoviocytes (MH7A line) from patients with rheumatoid arthritis (RA). DBA/1 mice were immunized with bovine type II collagen and orally administered FLE for 14 days. On day 36, mouse sera and ankle joints were collected for serological and histological analysis, respectively. Consuming FLE inhibited RA development, suppressing pro-inflammatory cytokine productions, synovial inflammation, and cartilage degradation. The therapeutic effects of FLE in CIA mice were similar to those of methotrexate (MTX), which is typically used to treat RA. In vitro, FLE suppressed the transforming growth factor-ß (TGF-ß)/Smad signaling pathway in MH7A cells. We also demonstrated that FLE inhibited TGF-ß-induced cell migration, suppressed MMP-2/9 expression, inhibited MH7A cell proliferation, and increased the expression of autophagy markers LC3B and p62 in a dose-dependent manner. Our data suggest that FLE could induce autophagosome formations in the early of stages of autophagy while inhibiting their degradation in the later stages. In conclusion, FLE is a potential therapeutic agent for RA.

Effects of Fermented Garlic Extract Containing Nitric Oxide Metabolites on Blood Flow in Healthy Participants: A Randomized Controlled Trial.

Aged or fermented garlic extract (FGE) is a natural remedy that improves vascular function through increasing vascular nitric oxide (NO) bioavailability. This is because nitrite (NO2-), a NO metabolite, can be produced through bioconversion with macrobacteria during the fermentation of foods like garlic. We aimed to evaluate the effects of NO2- in FGE on blood flow (BF), blood pressure (BP), velocity of the common carotid artery (CCA) and internal carotid artery (ICA), regional cerebral BF (rCBF), and peripheral BF (PBF). The study was divided into two parts: (1) Thirty healthy adults were divided into FGE and placebo groups to compare BP and velocity of the CCA and ICA; and (2) Twenty-eight healthy adults were divided into FGE and placebo groups to compare rCBF and PBF and determine changes before/after ingestion. Significant changes were noted in BP and the velocity of both CCA 30-60 min after FGE ingestion. FGE ingestion resulted in significant increases in rCBF and increases in body surface temperature through alterations in PBF. No detectable clinical side effects were noted. Overall, oral administration of NO2- containing FGE demonstrated acute positive effects in upregulating BF, including the CCA, BP, rCBF, and PBF. Follow-up studies with larger sample sizes and long-term ingestion may be needed.

Feasibility of dance therapy using telerehabilitation on trunk control and balance training in patients with stroke: A pilot study.

BACKGROUND: This randomized controlled trial aimed to investigate the effects of dance therapy using telerehabilitation on trunk control and balance training in patients with stroke and compare them with the effects of conventional treatment. METHODS: We enrolled 17 patients with subacute or chronic stroke who were randomly assigned to either an experimental or a control group. In addition to conventional physical therapy, the experimental group (n = 9) participated in 40-minute, non-face-to-face, dance-therapy sessions and the control group (n = 8) received conventional physical therapy. The primary outcome measures were the Trunk Impairment Scale (TIS) scores to assess trunk control and balance function between the 2 groups as a measure of change from baseline to after the intervention. RESULTS: We found that the TIS scores of the patients in the experimental group significantly improved (P = .017). The TIS results indicated non-inferiority within a predefined margin for dance therapy using telerehabilitation (difference = -0.86, 95% confidence interval [CI] = -2.21 to 0.50). CONCLUSION: Dance therapy using telerehabilitation significantly improved the TIS scores in the experimental group and was not inferior to conventional rehabilitation treatment when compared in a non-inferiority test. The remote dance program may therefore have similar effects to those of conventional treatment regarding trunk-control improvement in patients with stroke.

Evaluation of the Effectiveness of Fermented Soybean-Lettuce Powder for Improving Menopausal Symptoms.

Menopause syndrome causes a decline in the quality of life of postmenopausal women. Hormone therapy is recommended for the treatment of menopausal syndromes. However, it has several side effects. Soybean has been safely used to relieve the symptoms of menopause. Lettuce has antidiabetic and anti-inflammatory effects and improves sleep quality. Natural nitric oxide metabolites are produced through fermentation, which increases the effectiveness of the functional substances. This study assessed the alleviation of menopausal syndrome symptoms by natural nitric oxide-containing soybean lettuce extract using the Kupperman index. This study included adult women with menopausal syndrome and a Kupperman index of ≥15. After a four-week study with 40 participants, the final analysis included 39 participants in the experimental group (n = 19) and the placebo group (n = 20). Body mass index, waist circumference, and the total cholesterol, low-density and high-density lipoprotein cholesterol, and triglyceride levels were not altered before and after treatment in both groups. There was a significant decrease in the Kupperman index after treatment in the experimental group, but no significant change was observed in the placebo group. Soybean lettuce extract alleviates menopause syndrome without any special side effects.

Benefits of a Skull-Interfaced Flexible and Implantable Multilight Emitting Diode Array for Photobiomodulation in Ischemic Stroke.

Photobiomodulation (PBM) has received attention due to its potential for improving tissue function and enhancing regeneration in stroke. A lightweight, compact, and simple system of miniaturized electronic devices consisting of packaged light-emitting diodes (LEDs) that incorporates a flexible substrate for in vivo brain PBM in a mouse model is developed. Using this device platform, the preventive and therapeutic effects of PBM affixed to the exposed skull of mice in the photothrombosis and middle cerebral artery occlusion stroke model are evaluated. Among the wavelength range of 630, 850, and 940 nm LED array, the PBM with 630-nm LED array is proved to be the most effective for reducing the infarction volume and neurological impairment after ischemic stroke. Moreover, the PBM with 630 nm LED array remarkably improves the capability of spatial learning and memory in the chronic poststroke phase, attenuates AIM2 inflammasome activation and inflammasome-mediated pyroptosis, and modulates microglial polarization in the hippocampus and cortex 7 days following ischemic stroke. Thus, PBM may prevent tissue and functional damage in acute ischemic injury, thereby attenuating the development of cognitive impairment after stroke.

Nutritional Supplementation in Stroke Rehabilitation: A Narrative Review.

Malnutrition is associated with increased mortality and poor functional recovery after stroke. Most guidelines for stroke rehabilitation strongly recommend nutritional screening for malnutrition. Nutritional status after stroke is related to long-term outcomes, and nutritional supplementation is recommended for stroke patients with malnutrition and those at risk of malnutrition. However, routine nutritional supplementation in stroke patients, regardless of nutritional status, is not correlated with improved functional outcomes, and nutritional supplementation is not recommended if the nutritional status is adequate. Nutritional supplementation with protein, amino acids, vitamins, and minerals positively affects recovery after stroke, with improvements seen in motor function, cognition, activities of living, and mood. However, the evidence is insufficient due to the small number of studies and the lack of well-designed randomized controlled studies. Therefore, nutritional supplementation for stroke patients in rehabilitation should not be uniform, and individual nutritional interventions based on an assessment of the patient's nutritional status should be provided.

Effects of Photobiomodulation on Changes in Cognitive Function and Regional Cerebral Blood Flow in Patients with Mild Cognitive Impairment: A Pilot Uncontrolled Trial.

BACKGROUND: Photobiomodulation (PBM) affects local blood flow regulation through nitric oxide generation, and various studies have reported on its effect on improving cognitive function in neurodegenerative diseases. However, the effect of PBM in the areas of the vertebral arteries (VA) and internal carotid arteries (ICA), which are the major blood-supplying arteries to the brain, has not been previously investigated. OBJECTIVE: We aimed to determine whether irradiating PBM in the areas of the VA and ICA, which are the major blood-supplying arteries to the brain, improved regional cerebral blood flow (rCBF) and cognitive function. METHODS: Fourteen patients with mild cognitive impairments were treated with PBM. Cognitive assessment and single-photon emission computed tomography were implemented at the baseline and at the end of PBM. RESULTS: Regarding rCBF, statistically significant trends were found in the medial prefrontal cortex, lateral prefrontal cortex, anterior cingulate cortex, and occipital lateral cortex. Based on the cognitive assessments, statistically significant trends were found in overall cognitive function, memory, and frontal/executive function. CONCLUSION: We confirmed the possibility that PBM treatment in the VA and ICA areas could positively affect cognitive function by increasing rCBF. A study with a larger sample size is needed to validate the potential of PBM.

Electroacupuncture on the Scalp over the Motor Cortex Ameliorates Behavioral Deficits Following Neonatal Hypoxia-Ischemia in Rats via the Activation of Neural Stem Cells.

Electroacupuncture (EA) therapy via alternating current stimulation on the scalp over the motor cortex is used for the treatment of brain disorders. Perinatal hypoxia-ischemia (HI), a brain injury in newborns, leads to long-term neurologic complications. Here, we investigated whether EA could promote functional improvements and neurogenesis in a neonatal HI rat model. A neonatal HI rat model was induced by permanent ligation of the left carotid artery in postnatal day 7 pups. EA for neonatal HI rats was performed at 2 Hz (1, 3, or 5 mA; 20 min) from 4-6 weeks after birth. HI rats undergoing EA had improved motor and memory function, with the greatest improvement after 3 mA EA. The corpus callosum was significantly thicker and showed a significant increase in proliferating astrocytes in the 3 mA EA group. We observed proliferating cells and a greater number of newly developed neurons and astrocytes in the subventricular zone and dentate gyrus of the 3 mA EA group than in those of the HI group. These results suggest that EA promotes functional improvements following neonatal HI assault via the proliferation and differentiation of neural stem cells. This effect was the strongest after 3 mA EA, suggesting that this is the optimal treatment dose.

Photobiomodulation Using a Low-Level Light-Emitting Diode Improves Cognitive Dysfunction in the 5XFAD Mouse Model of Alzheimer's Disease.

Photobiomodulation using low-level light-emitting diode can be rapidly applied in neurological and physiological disorders safely and noninvasively. Photobiomodulation is effective for chronic diseases because of fewer side effects than drugs. Here we investigated the effects of photobiomodulation using light-emitting diode on amyloid plaques, gliosis, and neuronal loss to prevent and/or recover cognitive impairment, and optimal timing of photobiomodulation initiation for recovering cognitive function in a mouse model of Alzheimer's disease. 5XFAD mice were used as an Alzheimer's disease model. Animals receiving photobiomodulation treatment were divided into two groups: an early group starting photobiomodulation at 2 months of age (5XFAD+Early), and a late group starting photobiomodulation at 6 months of age (5XFAD+Delay). Both groups received photobiomodulation 20 minutes per session three times per week for 14 weeks. The Morris water maze, passive avoidance, and elevated plus maze tests were performed at 10 months of age. Immunohistochemistry and Western blot were performed after behavioral evaluation. The results showed that photobiomodulation treatment at early stages reduced amyloid accumulation, neuronal loss, and microgliosis and alleviated the cognitive dysfunction in 5XFAD mice, possibly by increasing insulin degrading enzyme related to amyloid-beta degradation. Photobiomodulation may be an excellent candidate for advanced preclinical Alzheimer's disease research.

Therapeutic Potential of a Combination of Electroacupuncture and TrkB-Expressing Mesenchymal Stem Cells for Ischemic Stroke.

We prepared and grafted tropomyosin receptor kinase B (TrkB) gene-transfected mesenchymal stem cells (TrkB-MSCs) into the ischemic penumbra and investigated whether electroacupuncture (EA) treatment could promote functional recovery from ischemic stroke. For the behavioral test, TrkB-MSCs+EA resulted in significantly improved motor function compared to that obtained with MSCs+EA or TrkB-MSCs alone. At 30 days after middle cerebral artery occlusion (MCAO), the largest number of grafted MSCs was detected in the TrkB-MSC+EA group. Some differentiation into immature neuroblasts and astrocytes was detected; however, only a few mature neuron-like cells were found. Compared to other treatments, TrkB-MSCs+EA upregulated the expression of mature brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT4) and induced the activation of TrkB receptor and its transcription factor cAMP response element-binding protein (CREB). At 60 days after MCAO, EA highly promoted the differentiation of TrkB-MSCs into mature neuron-like cells compared to the effect in MSCs. A selective TrkB antagonist, ANA-12, reverted the effect of TrkB-MSCs+EA in motor function recovery and survival of grafted MSCs. Our results suggest that EA combined with grafted TrkB-MSCs promotes the expression of BDNF and NT4, induces the differentiation of TrkB-MSCs, and improves motor function. TrkB-MSCs could serve as effective therapeutic agents for ischemic stroke if used in combination with BDNF/NT4-inducing therapeutic approaches.

Potential benefits of mesenchymal stem cells and electroacupuncture on the trophic factors associated with neurogenesis in mice with ischemic stroke.

The beneficial effects of mesenchymal stem cells (MSCs) and electroacupuncture (EA) on neurogenesis and related trophic factors remain unclear. Bone marrow MSCs (mBMSC) were transplanted into the striatum of mice with middle cerebral artery occlusion (MCAO), and EA stimulation was applied at two acupoints, Baihui and Dazhui. EA treatment significantly improved motor function, and a synergistic effect of combined mBMSC and EA treatment was observed. Combined mBMSC and EA treatment reduced prominent atrophic changes in the striatum and led to proliferation of neural progenitor cells in the subventricular zone (SVZ) and the surrounding areas of the striatum (SVZ + striatum) of MCAO mice. The mBMSC and EA treatment markedly enhanced mature brain-derived neurotrophic factor (mBDNF) expression in the SVZ + striatum and hippocampus of mice with MCAO, and combined treatment enhanced neurotrophin-4 (NT4) expression. The number of mBDNF- and NT4-positive neurons in the SVZ + striatum and hippocampus increased following EA treatment. Combined treatment led to an increase in the expression levels of phosphorylated cAMP response element binding protein in the neuroblasts of the striatum. Our results indicate that combined MSC and EA treatment may lead to a better therapeutic effect via co-regulation of neurotrophic factors in the brain, by regulating neurogenesis more than single therapy.

Low-level light emitting diode therapy promotes long-term functional recovery after experimental stroke in mice.

We aimed to investigate the effects of low-level light emitting diode therapy (LED-T) on the long-term functional outcomes after cerebral ischemia, and the optimal timing of LED-T initiation for achieving suitable functional recovery. Focal cerebral ischemia was induced in mice via photothrombosis. These mice were assigned to a sham-operated (control), ischemic (vehicle), or LED-T group [initiation immediately (acute), 4 days (subacute) or 10 days (delayed) after ischemia, followed by once-daily treatment for 7 days]. Behavioral outcomes were assessed 21 and 28 days post-ischemia, and histopathological analysis was performed 28 days post-ischemia. The acute and subacute LED-T groups showed a significant improvement in motor function up to 28 days post-ischemia, although no brain atrophy recovery was noted. We observed proliferating cells (BrdU+ ) in the ischemic brain, and significant increases in BrdU+ /GFAP+ , BrdU+ /DCX+ , BrdU+ /NeuN+ , and CD31+ cells in the subacute LED-T group. However, the BrdU+ /Iba-1+ cell count was reduced in the subacute LED-T group. Furthermore, the brain-derived neurotrophic factor (BDNF) was significantly upregulated in the subacute LED-T group. We concluded that LED-T administered during the subacute stage had a positive impact on the long-term functional outcome, probably via neuron and astrocyte proliferation, blood vessel reconstruction, and increased BDNF expression. Picture: The rotarod test for motor coordination showed that acute and subacute LED-T improves long-term functional recovery after cerebral ischemia.

Pretreatment with light-emitting diode therapy reduces ischemic brain injury in mice through endothelial nitric oxide synthase-dependent mechanisms.

Photostimulation with low-level light emitting diode therapy (LED-T) modulates neurological and psychological functions. The purpose of this study was to evaluate the effects of LED-T pretreatment on the mouse brain after ischemia/reperfusion and to investigate the underlying mechanisms. Ischemia/reperfusion brain injury was induced by middle cerebral artery occlusion. The mice received LED-T twice a day for 2 days prior to cerebral ischemia. After reperfusion, the LED-T group showed significantly smaller infarct and edema volumes, fewer behavioral deficits compared to injured mice that did not receive LED-T and significantly higher cerebral blood flow compared to the vehicle group. We observed lower levels of endothelial nitric oxide synthase (eNOS) phosphorylation in the injured mouse brains, but significantly higher eNOS phosphorylation in LED-T-pretreated mice. The enhanced phospho-eNOS was inhibited by LY294002, indicating that the effects of LED-T on the ischemic brain could be attributed to the upregulation of eNOS phosphorylation through the phosphoinositide 3-kinase (PI3K)/Akt pathway. Moreover, no reductions in infarct or edema volume were observed in LED-T-pretreated eNOS-deficient (eNOS-/-) mice. Collectively, we found that pretreatment with LED-T reduced the amount of ischemia-induced brain damage. Importantly, we revealed that these effects were mediated by the stimulation of eNOS phosphorylation via the PI3K/Akt pathway.

Low-level light emitting diode (LED) therapy suppresses inflammasome-mediated brain damage in experimental ischemic stroke.

Use of photostimulation including low-level light emitting diode (LED) therapy has broadened greatly in recent years because it is compact, portable, and easy to use. Here, the effects of photostimulation by LED (610 nm) therapy on ischemic brain damage was investigated in mice in which treatment started after a stroke in a clinically relevant setting. The mice underwent LED therapy (20 min) twice a day for 3 days, commencing at 4 hours post-ischemia. LED therapy group generated a significantly smaller infarct size and improvements in neurological function based on neurologic test score. LED therapy profoundly reduced neuroinflammatory responses including neutrophil infiltration and microglia activation in the ischemic cortex. LED therapy also decreased cell death and attenuated the NLRP3 inflammasome, in accordance with down-regulation of pro-inflammatory cytokines IL-1ß and IL-18 in the ischemic brain. Moreover, the mice with post-ischemic LED therapy showed suppressed TLR-2 levels, MAPK signaling and NF-kB activation. These findings suggest that by suppressing the inflammasome, LED therapy can attenuate neuroinflammatory responses and tissue damage following ischemic stroke. Therapeutic interventions targeting the inflammasome via photostimulation with LED may be a novel approach to ameliorate brain injury following ischemic stroke. Effect of post-ischemic low-level light emitting diode therapy (LED-T) on infarct reduction was mediated by inflammasome suppression.

Electroacupuncture ameliorates memory impairments by enhancing oligodendrocyte regeneration in a mouse model of prolonged cerebral hypoperfusion.

We modeled prolonged cerebral hypoperfusion in mice using bilateral common carotid artery stenosis (BCAS) and electroacupuncture (EA) stimulation was applied at two acupoints, Baihui (GV20) and Dazhui (GV14). In behavioral tests of memory, BCAS produced impairments in spatial and short-term memory in mice that were attenuated by therapeutic EA stimulation. Therapeutic use of EA in BCAS also enhanced oligodendrocyte (OL) differentiation from oligodendrocyte precursor cells (OPCs), in association with white matter improvements in the corpus callosum (CC). In PCR analyses of growth factor gene expression, significant positive changes in 3 genes were observed following EA stimulation in BCAS, and here we highlight alterations in neurotrophin-4/5 (NT4/5). We confirmed EA-mediated positive changes in the expression of NT4/5 and its receptor, tyrosine receptor kinase B (TrkB). Treatment of naïve and BCAS + EA animals with a selective TrkB antagonist, ANA-12, produced losses of myelin and cognitive function that were ameliorated by EA therapy. Moreover, following BCAS we observed an EA-dependent increase in phospho-activated CREB (a downstream mediator of NT4/5-TrkB signaling) in OPCs and OLs of the CC. Our results suggest that EA stimulation promotes the recovery of memory function following white matter injury via a mechanism that promotes oligodendrocyte regeneration and involves NT4/5-TrkB signaling.

Randomized controlled trial of the efficacy and safety of self-adhesive low-level light therapy in women with primary dysmenorrhea.

OBJECTIVE: To evaluate the efficacy and safety of low-level light therapy in women with primary dysmenorrhea. METHOD: A multicenter prospective, randomized, double-blind, placebo-controlled clinical trial including patients 18-35 years of age with primary dysmenorrhea was undertaken at two university hospitals in South Korea between October 2011 and September 2012. Patients were randomized using a computer-generated sequence to receive low-level light therapy using the Color DNA-WSF device or to receive placebo treatment with a dummy device. The severity of menstrual pain, assessed using a visual analog scale, was the primary outcome and was evaluated at baseline and during every menstrual cycle for 3 months following treatment. Patients who received more than one application of treatment (with a Color DNA-WSF or placebo device) were included in analyses. Patients and investigators were masked to the treatment assignments. RESULTS: Overall, 44 patients were assigned to each group. At the final study visit, the reduction in scores using a visual analog scale was significantly greater in patients who received low-level light therapy (n=41; 4.34±2.22) than among those in the control group (n=38; 1.79±1.73; P<0.001 when adjusted for age) No serious adverse events occurred. CONCLUSION: Low-level light therapy could be an effective, safe treatment modality for women with primary dysmenorrhea. Clinical Trials.gov: NCT02026206.

Effects of extradural cortical stimulation on motor recovery in a rat model of subacute stroke.

PURPOSE: Previous studies demonstrated that administering extradural cortical stimulation (ECS) to rats during the acute phase of a photothrombotic infarct enhances motor recovery. However, the effect of ECS during the subacute phase was unknown. We aimed to evaluate the effects of ECS on motor recovery in a rat model of subacute photothrombotic stroke. METHODS: Photothrombotic ischemic injury to the left sensorimotor cortex (SMC) was induced in 41 male Sprague-Dawley rats using Rose-bengal dye (20 mg/kg) and cold light. The rats were randomly divided into two groups: ECS on infarcted SMC (ECS group) and no ECS on infarcted SMC (non-stimulated group). The ECS group received continuous ECS for 14 days starting from day 5 after the stroke onset. Behavioral training with the single-pellet reaching task (SPRT) was performed daily for all of the rats from the fifth day after stroke onset. After 19 days, brain sections were immunostained to allow the quantification of infarct volumes and the evaluation of the neuronal markers. RESULTS: The SPRT scores showed significantly faster and greater improvement in the ECS group than in the non-stimulated group. There were no significant differences in infarct size. However, in the ECS group, significantly more doublecortin-labeled cells were identified close to the penumbra region of the cerebral cortex. CONCLUSIONS: ECS in the subacute phase improved the behavior motor function in the stroke rat model, and induced a significant axonal sprouting in the peri-infarct area.

An animal study to examine the effects of the bilateral, epidural cortical stimulation on the progression of amyotrophic lateral sclerosis.

BACKGROUND: We examined the effects of the unilateral cortical stimulation on the survival of neurons showing degenerative changes and compared those in delaying the progression of amyotrophic lateral sclerosis (ALS) between the unilateral cortical stimulation and the bilateral one in an animal experimental model using mice. METHODS: We used 19 G93A transgenic mice and randomly divided into three groups: the control group (n=6) (the implantation of electrodes in the bilateral motor cortex without electrical stimulation), the unilateral stimulation group (n=7) (the implantation of electrodes in the unilateral motor cortex with a 24-hour cortical stimulation) and the bilateral stimulation group (n=6) (the implantation of electrodes in the bilateral motor cortex with a 24-hour cortical stimulation). RESULTS: The mean survival period was significantly longer in the bilateral stimulation group as compared with the control group (124.33 ± 11.00 days vs. 109.50 ± 10.41 days) (P<0.05). In addition, on postoperative weeks 11, 12, 13, 14 and 15, the mean Rota-rod score was significantly higher in the unilateral stimulation group as compared with the control group (P<0.05). Furthermore, despite a lack of statistical significance, it was the lowest in the bilateral stimulation group on postoperative weeks 13, 14, 15 and 17. On postoperative weeks 11, 12, 13, 14 and 16, the mean score of paw-grip endurance was significantly higher in the unilateral stimulation group as compared with the control group (P<0.05). Furthermore, despite a lack of statistical significance, it was the lowest in the bilateral stimulation group on postoperative weeks 13, 14, 15 and 17. CONCLUSIONS: In conclusion, our results indicate that the bilateral epidural cortical stimulation might have a treatment effect in a murine model of ALS. But it is the limitation that we examined a small number of experimental animals. Further studies are therefore warranted to establish our results and to identify the optimal parameters of the epidural cortical stimulation in a larger number of experimental animals.

Acquiring the optimal time for hyperbaric therapy in the rat model of CFA induced arthritis.

BACKGROUND: We previously published an article about the pressure effect using a rheumatoid animal model. Hyperbaric therapy appears to be beneficial in treating rheumatoid arthritis (RA) by reducing the inflammatory process in an animal model. In this sense, acquiring the optimal pressure-treatment time parameter for RA is important and no optimal hyperbaric therapy time has been suggested up to now. OBJECTIVE: The purpose of our study was to acquire the optimal time for hyperbaric therapy in the RA rat model. STUDY DESIGN: Controlled animal study. METHODS: Following injection of complete Freund's adjuvant (CFA) into one side of the knee joint, 32 rats were randomly assigned to 3 different time groups (1, 3, 5 hours a day) under 1.5 atmospheres absolute (ATA) hyperbaric chamber for 12 days. The pain levels were assessed daily for 2 weeks by weight bearing force (WBF) of the affected limb. In addition, the levels of gelatinase, MMP-2, and MMP-9 expression in the synovial fluids of the knees were analyzed. RESULTS: The reduction of WBF was high at 2 days after injection and then it was spontaneously increased up to 14 days in all 3 groups. There were significant differences of WBF between 5 hours and control during the third through twelfth days, between 3 hours and control during the third through fifth and tenth through twelfth days, and between 3 hours and 5 hours during the third through seventh days (P < 0.05). The MMP-9/MMP-2 ratio increased at 14 days after the CFA injection in all groups compared to the initial findings, however, the 3 hour group showed a smaller MMP-9/MMP-2 ratio than the control group. LIMITATION: Although enough samples were used for the study to support our hypothesis, more samples will be needed to raise the validity and reliability. CONCLUSION: The effect of hyperbaric treatment appears to be dependent upon the elevated therapy time under 1.5 ATA pressure for a short period of time; however, the long-term effects were similar in all pressure groups. Further study will be needed to acquire the optimal pressure-treatment parameter relationship in various conditions for clinical application.