Beneficial Pharmacological Effects of Levosimendan on Antioxidant Status of Acute Inflammation Induced in Paw of Rat: Involvement in Inflammatory Mediators

Levosimendan (LEVO) is a new calcium sensitizer with positive inotropic and vasodilating properties that represents a new pharmacological class of inotropic drugs that stimulate elevated cardiac output. The purpose of this study was to examine anti‐inflammatory effect and antioxidant activity of LEVO in a carrageenan (CAR)‐induced inflammatory paw oedema rat model. The CAR‐induced rat groups received LEVO 1, 2 and 3 mg/kg by intraperitonally and indomethacin (IND) 25 mg/kg by oral gavage. LEVO inhibited CAR‐induced paw oedema and suppressed the production of TNF‐α, IL‐1 and IL‐6 at doses of 2 and 3 mg/kg. In contrast to CAR‐injected paws, 2 and 3 mg/kg doses of LEVO and IND increased superoxide dismutase (SOD) activity and also both doses of LEVO, and IND decreased the 8‐isoprostaglandin F2α (8‐ISO) level. A 2 mg/kg dose of LEVO produced 39%, 46%, 61% and 64.7% anti‐inflammatory effects (p < 0.0001) for the 1st, 2nd, 3rd and 4th hours, respectively. Other results of our current study have shown that SOD and glutathione for CAR‐injected groups were lower, and 8‐ISO level was higher than those for the healthy rat group. LEVO may be provided as a pharmacological agent in the prevention or treatment of diseases in which acute or chronic inflammation occurs based on a pathogenic factor.     

Effects of Amburoside A and Isokaempferide,Polyphenols from Amburana cearensis,on Rodent Inflammatory Processes and Myeloperoxidase Activity in Human Neutrophils

Abstract: The present study evaluated the anti‐inflammatory activity of amburoside A (a phenol glucoside) and isokaempferide (a flavonol) isolated from the trunk bark of Amburana cearensis, a medicinal plant used in northeast Brazil for the treatment of asthma. Animals (male Wistar rats or Swiss mice) pre‐treated with amburoside A (25 and 50 mg/kg) or isokaempferide (12.5, 25 and 50 mg/kg), orally or intraperitoneally, showed a significant inhibition of the paw oedema induced by carrageenan (1%), prostaglandin E₂ (30 nmol/paw), histamine (200 µg/paw) or serotonin (200 µg/paw). Histological and morphometric evaluations of the rat paw oedema induced by carrageenan showed that amburoside A and isokaempferide also inhibited the accumulation of inflammatory cells. Amburoside A reduced significantly the paw oedema and the increase in vascular permeability induced by dextran, as related to the control group. Similar results were observed with the isokaempferide pre‐treatment. Furthermore, amburoside A or isokaempferide inhibited both leucocyte and neutrophil migrations, in mouse peritoneal cavity, after the carrageenan injection. The polyphenols were not cytotoxic and blocked N‐formyl‐methyl‐leucyl‐phenylalanine‐induced myeloperoxidase release and activity in human neutrophils. In addition, amburoside A and isokaempferide at 50 and 100 µg/ml concentrations reduced significantly the lipopolysaccharide‐mediated increase in tumour necrosis factor‐α (TNF‐α) levels. These results provide, for the first time, evidence to support the anti‐inflammatory activity of amburoside A and isokaempferide that seems to be related to an inhibition of inflammatory mediators, such as TNF‐α, as well as histamine, serotonin and prostaglandin E₂, besides leucocyte infiltration in a dose‐ or concentration‐dependent manner. These anti‐inflammatory effects can be explained, at least in part, by the ability of these compounds to reduce neutrophil degranulation, myeloperoxidase activity, mediators as well as TNF‐α secretion.     

Peripheral Antinociception and Anti‐Inflammatory Effects of Sulphated Polysaccharides from the Alga Caulerpa mexicana

Sulphated polysaccharides from marine algae are widely used in biotechnological and pharmaceutical areas. In this study, we evaluated the effects of sulphated polysaccharides from the green marine alga Caulerpa mexicana (Cm‐SPs) in nociceptive and inflammatory models in rodents. Cm‐SPs (10 or 20 mg/kg), administered i.v. in Swiss mice, significantly reduced nociceptive responses, as measured by the number of writhes in response to acetic acid. Cm‐SPs (10 or 20 mg/kg) also reduced second‐phase responses in the formalin test, but did not exhibit a significant antinociceptive effect in the hot plate test, suggesting that its antinociceptive action occurs through a peripheral mechanism. Cm‐SPs (5, 10 or 20 mg/kg), administered s.c. in wistar rats 1 hr before carrageenan, dextran, histamine or serotonin, were tested in paw oedema models. Cm‐SPs (10 or 20 mg/kg) reduced carrageenan‐induced paw oedema and myeloperoxidase activity in the paw. In addition, Cm‐SPs (20 mg/kg) inhibited dextran‐ or histamine‐induced paw oedema, but not serotonin‐induced oedema, suggesting that histamine is the major target of Cm‐SPs anti‐oedematogenic activity. Finally, Cm‐SPs (20 mg/kg) administered in mice did not show significant signs of toxicity. In conclusion, Cm‐SPs appear to be promising natural modulatory agents for pain and inflammatory conditions.     

Anti‐inflammatory Effect of Rosmarinic Acid and an Extract of Rosmarinus officinalis in Rat Models of Local and Systemic Inflammation

Rosmarinic acid is a polyphenolic compound and main constituent of Rosmarinus officinalis and has been shown to possess antioxidant and anti‐inflammatory properties. We aimed to evaluate the anti‐inflammatory properties of rosmarinic acid and of an extract of R. officinalis in local inflammation (carrageenin‐induced paw oedema model in the rat), and further evaluate the protective effect of rosmarinic acid in rat models of systemic inflammation: liver ischaemia–reperfusion (I/R) and thermal injury models. In the local inflammation model, rosmarinic acid was administered at 10, 25 and 50 mg/kg (p.o.), and the extract was administered at 10 and 25 mg/kg (equivalent doses to rosmarinic acid groups) to male Wistar rats. Administration of rosmarinic acid and extract at the dose of 25 mg/kg reduced paw oedema at 6 hr by over 60%, exhibiting a dose–response effect, suggesting that rosmarinic was the main contributor to the anti‐inflammatory effect. In the liver I/R model, rosmarinic acid was administered at 25 mg/kg (i.v.) 30 min. prior to the induction of ischaemia and led to the significant reduction in the serum concentration of transaminases (AST and ALT) and LDH. In the thermal injury model, rosmarinic acid was administered at 25 mg/kg (i.v.) 5 min. prior to the induction of injury and significantly reduced multi‐organ dysfunction markers (liver, kidney, lung) by modulating NF‐κB and metalloproteinase‐9. For the first time, the anti‐inflammatory potential of rosmarinic acid has been identified, as it causes a substantial reduction in inflammation, and we speculate that it might be useful in the pharmacological modulation of injuries associated to inflammation.     

OXACEPROL, AN ATYPICAL INHIBITOR OF INFLAMMATION AND JOINT DAMAGE

Oxaceprol, an established therapeutic agent for osteoarthritis, had no effect on macrophage prostaglandin E₂releasein vitroand inhibited carrageenan paw oedema at high doses (18–150mg/kg p.o.). In the same dose range, oxaceprol was comparable to indomethacin (3mg/kg p.o.) as an inhibitor of yeast hyperalgaesia and at 6–50mg/kg/day p.o. had a mild, variable inhibitory effect on cotton pellet granuloma formation. In adjuvant arthritic rats, oxaceprol (6–54mg/kg/day p.o.) given therapeutically had no effect on the primary paw oedema response, but inhibited secondary lesions in the ears and tail. Histologically, oxaceprol markedly inhibited inflammatory cell infiltration and bone damage in the adjuvant-injected paw. In contrast to indomethacin, oxaceprol was more effective at inhibiting periarticular soft tissue inflammation but did not affect cartilage breakdown in this model. Oxaceprol has a clearly different spectrum of action to NSAIDs such as indomethacin and may act by inhibiting leucocyte infiltration and late connective tissue changes during inflammatory joint disease.     

Isopropoxy‐Carvacrol,a Derivative Obtained from Carvacrol,Reduces Acute Inflammation and Nociception in Rodents

Monoterpenes, compounds mainly presented in essential oils, have important pharmacological actions. Isopropoxy‐carvacrol (IPC) is a derivative of the monoterpene carvacrol, and its pharmacological properties have not yet been investigated. The aim of this study was to analyse the acute anti‐inflammatory and antinociceptive properties of IPC. Mice (25–30 g) and rats (150–230 g) were pre‐treated (i.p.) with IPC at the doses of 10, 30 or 100 mg/kg or vehicle (Tween 80, 0.5%), 30 min. before injection of the phlogistic agents. Both the first and the second phases of formalin‐induced nociception were significantly reduced by IPC (100 mg/kg). Injection of carrageenan in mice paw reduced the threshold of stimulus intensity, applied with an analgesymeter, necessary to cause paw withdrawal, which was significantly reduced by 100 mg/kg of IPC. The area under curve (0–4 hr) of rat paw oedema induced by injection of carrageenan was also significantly diminished by the administration of IPC (100 mg/kg). Administration of 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) markedly increased mice ear oedema and myeloperidase (MPO) activity. Topical co‐administration of IPC (0.3–3 mg/ear) during the induction did not affect TPA‐induced ear oedema, but significantly decreased MPO activity in the ears, when compared with the vehicle. In in vitro experiments, IPC reduced lipoperoxidation induced by different stimuli, showed nitric oxide scavenger activity and did not interfere with murine macrophage viability in concentrations up to 100 μg/mL. These results demonstrate that IPC exerts acute anti‐inflammatory and antinociceptive activities, suggesting that it may represent an alternative in the development of new future therapeutic strategies.     

Anti-inflammatory, analgesic and antipyretic effects of friedelin isolated from Azima tetracantha Lam. in mouse and rat models

Objectives Friedelin was isolated from Azima tetracantha Lam. leaves collected from Kallakurichi, Villuppuram district, Tamil Nadu, India. The anti‐inflammatory, analgesic and antipyretic activities of friedelin have been investigated in Wistar rats and mice. Methods Friedelin was isolated from the hexane extract of leaves of A. tetracantha using column chromatography. The effects of friedelin on inflammation were studied by using carrageenan‐induced hind paw oedema, croton oil‐induced ear oedema, acetic acid‐induced vascular permeability, cotton pellet‐induced granuloma and adjuvant‐induced arthritis. The analgesic effect of friedelin was evaluated using the acetic acid‐induced abdominal constriction response, formalin‐induced paw licking response and the hot‐plate test. The antipyretic effect of friedelin was evaluated using the yeast‐induced hyperthermia test in rats. Key findings In the acute phase of inflammation, maximum inhibitions of 52.5 and 68.7% (P < 0.05) were noted with 40 mg/kg friedelin in carrageenan‐induced paw oedema and croton oil‐induced ear oedema, respectively. Administration of friedelin (40 mg/kg) significantly (P < 0.05) decreased the formation of granuloma tissue induced by cotton pellet at a rate of 36.3%. In the adjuvant‐induced arthritis test friedelin inhibited 54.5% of paw thickness. Friedelin inhibited acetic acid‐induced vascular permeability in mice. Friedelin also produced significant (P < 0.05) analgesic activity in the acetic acid‐induced abdominal constriction response and formalin‐induced paw licking response. In the hot‐plate test, friedelin did not show any significant results when compared with control. Treatment with friedelin showed a significant (P < 0.05) dose‐dependent reduction in pyrexia in rats. Conclusions The results suggested that friedelin possessed potent anti‐inflammatory, analgesic and antipyretic activities.     

Comparison between plethysmometer and micrometer methods to measure acute paw oedema for screening anti-inflammatory activity in mice

The present study was undertaken to evaluate the sensitivity of the plethysmometer and micrometer, which are the most commonly employed methods to measure the paw oedema for screening anti-inflammatory agents. Acute paw swelling was induced by s.c. injection of 0.02 ml carrageenan in mice. The maximum paw oedema (59.4%) was found to be at 3.5 h after injection of carrageenan in the hind paw of mice. Oral indomethacin treatment in the dose of 5 mg/kg 1 h prior to the induction of paw oedema, caused a significant (P < 0.05) reduction in paw swelling, when the plethysmometer method was used. When the micrometer method was used to measure the paw swelling, oral indomethacin at the dose of 1 mg/kg resulted in a significant reduction in paw oedema. These findings suggest that micrometer method is more sensitive to detect the lowest antiinflammatory dose of indomethacin when compared with the plethysmometer method. The possible significance of these findings is discussed.     

Antiinflammatory Effects of Moringa oleifera Root Extract

A crude methanol extract of the root of the plant Moringa oleifera Lam. was screened for anti inflammatory effect using the rat paw edema and the rat 6-day air pouch inflammatory models. Following oral administration, the extract inhibited carrageenan-induced rat paw edema in a dose-dependent manner, with 50% inhibitory concentration - IC 50 (dose producing 50% inhibition) of 660 mg/kg. On the 6-day air pouch acute inflammation induced with carrageenan, the extract was much more potent, with IC 50 values of 302.0 mg/kg and 315.5 mg/kg, for the inhibition of cellular accumulation and fluid exudation, respectively. Maximum inhibition obtained with 600 mg/kg were 83.8% and 80.0%, respectively. When delayed (chronic) inflammation was induced in the 6-day air pouch model using Freund’s complete adjuvant, the extract was still effective though less than in acute inflammation. In contrast, a moderate dose of indomethacin (5 mg/kg) inhibited the acute, but not the delayed form of air pouch inflammation. Acute toxicity tests in mice suggest very low toxicity. These results suggest that the root of Moringa oleifera contains anti inflammatory principle(s) that may be useful in the treatment of both the acute and chronic inflammatory conditions.     

Studies on the anti-inflammatory effect of fluoxetine in the rat.

The anti-inflammatory activity of fluoxetine, a selective serotonin reuptake inhibitor (SSRI), was studied on the carrageenan-induced paw inflammation in the rat. Fluoxetine (10-60 mg kg(-1)) given intraperitoneally (i.p.) 30 min before carrageenan, displayed marked anti-inflammatory activity, inhibiting paw oedema by 38.6-77.7% at 2 h post-carrageenan. Fluoxetine administered at time of carrageenan injection or 30 min after carrageenan challenge, markedly inhibited the paw oedema response. Rats administered daily fluoxetine (20 mg kg(-1), i.p.) showed significantly decreased inflammatory response to subplantar carrageenan when examined on the 5th and 14th day of fluoxetine injection. Fluoxetine (10 or 20 mg kg(-1), i.p.) co-administered with indomethacin (IND) (20 mg kg(-1), i.p.), celecoxib (10 mg kg(-1), i.p.) or rofecoxib (4.5 mg kg(-1), i.p.) before carrageenan reduced the anti-oedema effect of indomethacin or celecoxib, but had additive effect to that of rofecoxib. The anti-oedema effects of fluoxetine and melatonin or the tricyclic antidepressant imipramine were additive. In contrast, administration of both fluoxetine and the heterocyclic antidepressant trazodone had no greater anti-inflammatory effect than fluoxetine alone. The anti-oedema effect of fluoxetine was partially suppressed by the opioid antagonist naloxone (4 mg kg(-1), i.p.). Fluoxetine (360 or 720 microg per paw) given into the rat paw with carrageenan reduced the oedema response by 25.4 and 35.3% 4 h post-carrageenan, respectively. It is suggested that fluoxetine alone or co-administered with either imipramine or melatonin would be of benefit in the sitting of neuropathic or inflammatory pain conditions. Both the serotonergic and the opioid systems are likely to be involved in the modulating action of fluoxetine on peripheral inflammation.     

Anti-inflammatory activity of the non-peptidyl low molecular weight radical scavenger IAC in carrageenan-induced oedema in rats

Objective In this research we investigated the anti‐inflammatory activity of a non‐peptidyl low molecular weight radical scavenger (IAC) in an acute and chronic animal model of inflammation. Methods For this purpose the effect of IAC (10, 25, 50 mg/kg) was tested in rats on the associated behavioral responses to subsequent inflammatory and noxious challenges, such as hind paw oedema induced by intra‐plantar injection of carrageenan and granuloma induced by subcutaneous implant of a cotton pellet, using indometacin (2.5 mg/kg) as reference drug. Moreover, the serum level of several cytokines was tested in the animal treated (or not) with IAC (50 mg/kg) both in the absence and presence of carrageenan‐induced inflammation. Key findings IAC showed a significant anti‐inflammatory activity in both in acute and chronic models of inflammation. In addition IAC down regulated significantly the serum levels of interleukin (IL) 2 and IL6 whereas it increased the serum concentration of IL1α and glutathione. Conclusion Although it remains to be elucidated whether or not the antioxidant property of IAC is directly responsible for the modulation of the tested cytokines, these results suggest IAC to be a possible candidate for a novel anti‐inflammatory compound     

Letter from the Editor

This study investigated the antinociceptive and anti‐inflammatory activities of the ethanolic extract (EESAl), fractions and the compound 8‐methoxylapachenol (8ML) obtained from the tubers of Sinningia allagophylla. Male Swiss mice were treated with EESAl (3–300 mg/kg) or vehicle by oral route (p.o.) 1 hr before the injection of formalin 2.5% or carrageenan (Cg) into the hind paw. EESAl (3–30 mg/kg) reduced the inflammatory phase of the nociceptive behaviour induced by formalin (around 65% for all doses). EESAl (3–300 mg/kg, p.o.) also reduced Cg‐induced mechanical hyperalgesia and oedema in a dose‐dependent fashion but did not change the hot‐plate latency or the motor performance of the animals. Oral administration of petroleum ether fraction (PE, 3 mg/kg), but not in the methanolic fraction (30 mg/kg), reduced both Cg‐induced oedema and hyperalgesia. Compound 8ML isolated from PE (1.8 mg/kg, p.o.) abolished Cg‐induced hyperalgesia but also did not change hot‐plate latency or motor performance of the animals. 8ML administration into the paw (0.75–750 pg) dose‐dependently reduced Cg‐induced hyperalgesia. 8ML (750 pg) also blocked the hyperalgesia induced by tumour necrosis factor (TNF‐α), interleukin‐1β (IL‐1β) and prostaglandin E₂ (PGE₂) but failed to change the hyperalgesia induced by cytokine‐induced neutrophil chemoattractant‐1 (CINC‐1) and dopamine (Dopa). These results suggest that EESAl has an important antinociceptive and anti‐inflammatory activity, the former one related, at least in part, to the reduction in the hyperalgesia. Similarly, 8ML reduced Cg‐induced oedema and mechanical hyperalgesia and seems to act in peripheral sites and on the prostaglandin rather than on the sympathetic component of the Cg‐inflammatory hyperalgesia.     

Antinociceptive and anti‐inflammatory properties of 7‐hydroxycoumarin in experimental animal models: potential therapeutic for the control of inflammatory chronic pain

Objectives In the present study we investigated the antinociceptive, anti‐inflammatory and antipyretic effects of 7‐hydroxycoumarin (7‐HC) in animal models. Methods The effects of oral 7‐HC were tested against acetic acid‐induced writhing, formalin test, tail flick test, complete Freund's adjuvant (CFA)‐induced hypernociception, carrageenan‐induced paw oedema, lipopolysaccharide‐induced fever and the rota rod test. Key findings 7‐HC (3–60 mg/kg) produced a dose‐related antinociception against acetic acid‐induced writhing in mice and in the formalin test. In contrast, treatment with 7‐HC did not prevent thermal nociception in the tail flick test. A single treatment with 7‐HC, 60 mg/kg, produced a long‐lasting antinociceptive effect against CFA‐induced hypernociception, a chronic inflammatory pain stimulus. Notably, at 60 mg/kg per day over 4 days the administration of 7‐HC produced a continuous antinociceptive effect against CFA‐induced hypernociception. 7‐HC (30–120 mg/kg) produced anti‐inflammatory and antipyretic effects against carrageenan‐induced inflammation and lipopolysaccharide‐induced fever, respectively. Moreover, 7‐HC was found to be safe with respect to ulcer induction. In the rota rod test, 7‐HC‐treated mice did not show any motor performance alterations. Conclusions The prolonged antinociceptive and anti‐inflammatory effects of 7‐HC, in association with its low ulcerogenic activity, indicate that this molecule might be a good candidate for development of new drugs for the control of chronic inflammatory pain and fever.     

Anti-inflammatory effects of peripheral benzodiazepine receptor ligands in two mouse models of inflammation

In vivo treatment of mice with peripheral benzodiazepine receptor ligands exerts an inhibitory effect on the inflammatory response in two models of acute inflammation. In the first model, pretreatment of the animals (24 h) with 1-(2-chlorophenyl)-N-methyl-N(1-methylpropyl)-3-isoquinoline carboxamide (PK11195) and 7-chloro-5-(4-Chlorophenyl)-1, 3-dihydro-1-methyl-2-H-1,4-benzodiazepin-2 (Ro5-4864), at different doses (0.00001-10 mg/kg, i.p.) dose dependently inhibited the formation of mouse paw oedema induced by carrageenan with mean ID(50s) of 0.009 (95% confidence limits=0.0076-0.013) and 0.04 (95% confidence limits=0.025-0.0086) mg/kg, respectively. Both ligands (0. 1 mg/kg, i.p.) inhibited in the same way the mouse paw oedema induced by carrageenan in animals with and without adrenal glands. PK11195 and Ro5-4864 (0.1 mg/kg, i.p.) inhibited the mouse paw oedema induced by several inflammatory mediators. In the second model, the pretreatment (24 h) with peripheral benzodiazepine receptor ligands (0.1 mg/kg, i.p.) exerted an inhibitory effect on neutrophil influx and produce a marked inhibition of carrageenan-produced interleukin-13 and interleukin-6 in pleural exudation. Our results extend previous findings that peripheral benzodiazepine receptor is involved in the inflammatory response, and suggest that this action may be linked to the action of different inflammatory mediators, probably mainly by the inhibition of the release of pro-inflammatory cytokines.     

The anti-inflammatory effects of the phosphodiesterase inhibitor pentoxifylline in the rat.

The present study aimed to evaluate the anti-inflammatory effects of pentoxifylline (PTX), a non-specific phosphodiesterase inhibitor in the rat. Acute inflammation was induced by subplantar injection of carrageenan (1%) in the rat hind paw. Results showed that intraperitoneal (i.p.) administration of PTX (36 or 72 mg kg(-1)) 30 min prior to carrageenan reduced the paw oedema response in dose-dependent manner with a maximal effect of 18.9 and 40.1%, respectively, at 2h post-carrageenan (P<0.001 and <0.001 at respective doses). Theophylline given at equimolar doses (29.9 or 45.8 mg kg(-1), i.p.) did not reduce the oedema response. With higher doses of PTX (144-300 mg kg(-1), i.p.) the anti-oedema effect of the drug was more pronounced, but mainly confined to the first 2h following carrageenan injection and decreasing rapidly thereafter. PTX (72 mg kg(-1), i.p.) given 30 min after carrageenan challenge reduced the oedema response by 24.7 and 26.2% at 1 and 2h after dosing (P<0.05 and <0.05, respectively). PTX (36 or 72 mg kg(-1), i.p.) co-administered with indomethacin (5 mg kg(-1), i.p.) 30 min before carrageenan had little modulatory effect on the anti-oedema effect of indomethacin, but the higher dose of PTX (144 mg kg(-1), i.p.) reduced the anti-inflammatory effect of indomethacin by 24% at 4h post-carrageenan. PTX (72 mg kg(-1), i.p.) enhanced the anti-oedema effect of the selective COX-2 inhibitor celecoxib (33 mg kg(-1), i.p.) by 55.1% at 4h post-carrageenan. In contrast, the higher dose of PTX (144 mg kg(-1), i.p.) reduced the anti-oedema effect of celecoxib by 46.8% at 4h post-carrageenan. PTX (36 or 72 mg kg(-1)) enhanced the anti-oedema effect of dexamethasone (0.1 mg kg(-1)) with maximal effect of 76 and 104.8% at 2h post-carrageenan (P<0.01 and <0.01 for respective doses). PTX (0.6 mg per paw) given with carrageenan into the rat hind paw reduced the oedema response with a maximal effect of 33.4% at 1h following carrageenan. PTX (0.6 mg per paw) given in the contralateral hind paw reduced the carrageenan-induced paw oedema for 1h by 32.2%. Thus, PTX, when given at doses comparable to those used in man for treatment of circulatory disorders displayed anti-inflammatory in vivo and enhanced the anti-inflammatory effect of a selective COX-2 inhibitor or dexamethasone. PTX may have therapeutic potential as anti-inflammatory agent either alone or in combination with non-steroidal anti-inflammatory drugs or with steroids. There is also an intriguing possibility for the use of topical preparations for the management of local inflammatory conditions.     

Modulation of inflammatory paw oedema by cysteamine in the rat.

Cysteamine, a potent somatostatin depletor, was used in the present study to investigate the role of endogenous somatostatin in acute peripheral inflammation. The acute inflammation was induced by intraplantar injection of carrageenan (1%), histamine (5 micromol), or formalin (2.5%) in the rat hind paw. The induced inflammation and the formation of oedema were determined by measurement of the paw thickness. Given subcutaneously (s.c.) 1 h before carrageenan, cysteamine caused significant, dose-dependent and long-lasting inhibition of rat paw oedema induced by carrageenan. At doses of 12.5, 25, 50 or 100 mg kg (-1), cysteamine significantly inhibited the carrageenan-induced paw oedema at 4 h by 52.3, 40, 40.7 or 26.3%. Cysteamine given at 300 mg kg (-1), a dose well known to deplete tissue somatostatin, reduced oedema by only 16.2% vs control values. Significant inhibition of the carrageenan-induced rat paw oedema was still evident 24 h post-injection at cysteamine doses of 12.5, 25, 50 or 100 mg kg (-1). Given s.c. at 300 mg kg (-1), 4 h prior to carrageenan, cysteamine decreased rat paw oedema at 4 h by 14.9%. Cysteamine (300 mg kg (-1)), 4 h beforehand, had little modulatory effect on the oedema induced by formalin (2.5%) but reduced that caused by intraplantar histamine (5 micromol). The anti-oedematogenic effect of indomethacin, but not that of the selective COX-2 inhibitor celecoxib, was less marked in rats pre-treated with cysteamine at 300 mg kg (-1). Cysteamine (0.3 microg- 0.3 mg paw (-1)) co-administered with carrageenan was devoid of anti-inflammatory effect and even promoted inflammation at low concentrations. Cysteamine given locally alone induced slight paw oedema. These data indicate that systemic cysteamine possesses potent and long-lasting anti-inflammatory effects and modulates the anti-inflammatory effect of cyclooxygenase inhibitors in a model of peripheral inflammation in the rat. The effect of cysteamine is likely to be mediated via central action.     

Evaluation of the anti-inflammatory, anti-nociceptive and gastric effects of Ginkgo biloba in the rat.

Ginkgo biloba extract (GbE) was assessed in models of acute inflammation induced by carrageenan, formalin or capsaicin in the rat, in models of nociceptive pain, such as hot-plate (55 degrees C) latency, tail-electric stimulation assay and capsaicin-induced paw licking and in the model of acute gastric damage induced by indomethacin. The agent showed marked anti-inflammatory activity in the carrageenan model of paw oedema. When given subcutaneously (s.c.) (25 and 50 mg kg(-1)) 30 min before challenge, GbE inhibited paw oedema with a maximal effect of 43.7 and 56.9%, respectively, at 2h post-carrageenan. Significant inhibition of oedema was also observed when GbE (50 mg kg(-1), s.c.) was given 30 min after carrageenan challenge. The agent was also active p.o. in acute inflammation caused by carrageenan. The administration of GbE with indomethacin, rofecoxib, celecoxib, dexamethasone or melatonin resulted in an additive effect. GbE (50 mg kg(-1), s.c.) caused significant inhibition of formalin-induced paw oedema, but did not reduce the capsaicin-induced paw oedema. In tests of nociception, GbE (25, 50 or 100 mg kg(-1)) decreased in dose-dependent manner the capsaicin-induced hind paw licking time and was similarly effective in the hot-plate assay of nociception. In contrast, when assessed in the tail-electric stimulation test, GbE was only effective in the highest dose (100 mg kg(-1)). In pylorus-ligated rats, GbE (25 or 50 mg kg(-1)) increased gastric acid secretion, but reduced gastric mucosal damage caused by IND. Results suggest that GbE may be of clinical value as an anti-inflammatory and analgesic drug alone or in conjunction with NSAIDs.