Involvement of opioid receptors in the systemic and peripheral antinociceptive actions of ellagic acid in the rat formalin test.

Ellagic acid (EA) produced antinociceptive and anti-inflammatory effects. This study was conducted to investigate the involvement of opioid receptors in the systemic and peripheral antinociceptive effects of EA after intraperitoneal (i.p.) and intraplantar (i.pl.) administration in the rat formalin assay. The results showed that i.p. administration of EA (1-30 mg/kg) dose-dependently attenuated flinching number in both early and late phases of the formalin test with mean ED50 values of 1.86 and 0.52 mg/kg, respectively. Moreover, this effect of EA at a dose of 30 mg/kg was comparable to that of morphine (5mg/kg; i.p.) and indomethacin (10mg/kg; i.p.). It was also demonstrated that administration of EA (30-300 µg/paw; i.pl.) resulted in dose-dependent peripheral antinociception against early and late phases of formalin-induced nociception with mean ED50 values of 47.64 and 71.78 µg/paw, respectively. The antinociception produced by the i.pl. injection was due to a local action, as its administration in the contralateral paw was ineffective. Furthermore, pre-treatment with naloxone, a non-selective opioid antagonist, significantly alleviated the systemic and peripheral antinociceptive effects of EA. Also, EA treatment had no effect on the motor activity of rats when tested in open-field task. Our data suggest that the systemic and peripheral antinociception activities of EA were mediated through the opioid receptors in the periphery and also in the central nervous system.

Inhibition of the activation of hageman factor (factor XII) by eosinophils and eosinophilic constituents.

Several syndromes characterized by striking eosinophilia may be complicated by thrombosis. The experiments described indicate that, paradoxically, eosinophils and certain of their constituents inhibit the activation of Hageman factor (HF, factor XII). In earlier studies, suspensions of mixed types of granulocytes, other nucleated peripheral blood cells, and platelets inhibited activation of Hageman factor by ellagic acid, glass, and sulfatides. After these cells were sedimented by centrifugation, the supernatant fluids were also inhibitory. No attempt had been made earlier to distinguish among different granulocytic species. In the present study, suspensions of eosinophils and the supernatant fluid after eosinophils had been separated by centrifugation inhibited activation of Hageman factor by ellagic acid. The protein concentration of that amount of supernatant fluid that inhibited activation by about half was 16 micrograms/ml, approximately the same as had been described for suspensions of peripheral blood mononuclear cells. Activation of Hageman factor by ellagic acid was also inhibited by certain constituents of eosinophils, including eosinophil peroxidase, eosinophil major basic protein and eosinophil cationic protein. Inhibition was not specific for ellagic acid-induced activation of Hageman factor, as inhibition was also observed with sulfatide-induced activation. Inhibition was presumably related to neutralization of the negative charge of activators of Hageman factor. Thus, bismuth subgallate, a particulate activator of Hageman factor, was no longer effective after it had been exposed to eosinophil cationic protein. The observations reported here raise the question of whether in vivo eosinophils modulate certain of the defense reactions ascribed to Hageman factor.

Inhibition of the activation of Hageman factor (factor XII) by aprotinin (Trasylol)

Aprotinin (Trasylol; Bayer AG, Leverkusen, Germany), a protease inhibitor resembling or identical with Kunitz' pancreatic trypsin inhibitor, is said to have anticoagulant properties, but these are not clearly defined. The present study provides evidence that one action of aprotinin is inhibition of the activation of Hageman factor (factor XII).

Inhibition of the activation of Hageman factor (factor XII) by soluble human placental collagens types III, IV, and V.

The initial step in the formation of thrombin via the intrinsic pathway is the activation of Hageman factor (factor XII). Some, but not all, studies have shown that this activation may be brought about by collagen. We examined the effect of three types of soluble human placental collagen on Hageman factor. Collagen types III, IV, and V did not appear to activate Hageman factor under the conditions tested. To the contrary, these collagen species inhibited activation of Hageman factor by glass or ellagic acid. These studies suggest that some types of collagen may play an inhibitory role in blood coagulation.

Inhibition of the activation of Hageman factor (factor XII) by beta 2-glycoprotein I.

beta 2-Glycoprotein I (apolipoprotein H), a constituent of normal human plasma, has been shown to inhibit the generation of amidolytic activity in plasma that has been exposed to negatively charged agents. Studies with purified Hageman factor (factor XII) demonstrate that this inhibitory property is directed against the activation of Hageman factor. In this study beta 2-glycoprotein I inhibited the kaolin-induced generation of clot-promoting properties in solutions of Hageman factor. This effect was localized to an interaction between beta 2-glycoprotein I and kaolin. In contrast, once Hageman factor was activated by kaolin, its clot-promoting properties were not inhibited by beta 2-glycoprotein I. Further, beta 2-glycoprotein inhibited the generation of amidolytic activity against H-D-prolyl-L-phenylalanyl-L-arginine p-nitroanilide dihydrochloride in mixtures of Hageman factor and ellagic acid. The specificity of the action of beta 2-glycoprotein I was confirmed by its neutralization by immunoglobulin fractions of antiserums directed against this protein.

Inhibition of the activation of Hageman factor (factor XII) by complement subcomponent C1q.

Hageman factor (HF, Factor XII) is activated by glass, collagen, and ellagic acid, and initiates blood coagulation via the intrinsic pathway. C1q inhibits collagen-induced platelet aggregation and adherence of platelets to glass, effects attributable to the collagen-like region of C1q. We examined the actions of C1q on HF activation. Incubation of C1q with HF before addition of HF-deficient plasma extended the activated partial thromboplastin time. Similarly, when glass tubes were coated with C1q before testing, the partial thromboplastin time of normal plasma was increased. C1q reduced the activation of HF by ellagic acid, as measured by the release of p-nitroaniline from the synthetic substrate H-D-prolyl-L-phenylalanyl-L-arginine-p-nitroanilide dihydrochloride, an effect inhibited by monoclonal anti-human C1q murine IgG and by digestion of C1q by collagenase. Thus, C1q inhibits activation of HF in vitro in clot-promoting and amidolytic assays and suggests a regulatory mechanism for the inhibition of coagulation.

The thrombopenic effect of ellagic acid in the rat. Another model of platelet stimulation "in vivo".

In the rat, intravenous injection of large doses (30 mg/Kg) of ellagic acid (EA) induced a decrease in the plasma level of fibrinogen and in the blood platelet content and an increase of the activated partial thromboplastin time. The long-lasting thrombocytopenia was inhibited by heparin (4 mg/Kg), defibrase (20 U/Kg), clocoumarol (4 mg/Kg) and CCI 17810 (120 mg/Kg). It was not inhibited by aspirin (90 mg/Kg), indomethacin (8 mg/Kg), ketoprofen (4-10 mg/Kg), epsilon-aminocaproic acid (150 mg/Kg), methysergide (4 mg/Kg), chlorpromazine (10 mg/Kg) and promethazine (4 mg/Kg). On the contrary, the small doses of indomethacin (4 mg/Kg) and of ketoprofen (0.5-2 mg/Kg) increased the thrombopenic effect of EA. EA induced the accumulation of Cr51-labelled platelets into the lungs and the liver, accompanied by a 64% fall in Cr51 blood radioactivity. The platelet stimulating effect of EA would depend on an intravascular coagulation which occurs in the whole cardiovascular system. It is suggested that the pro-aggregating derivatives of arachidonic acid had a minor role in this stimulation. The intravascular coagulation induced by EA was accompanied by a swelling of the lymph nodes and of the spleen. In immune platelet depleted rats, EA induced only the swelling of lymph nodes.