Analgesic and anti-inflammatory actions on bradykinin route of a polysulfated fraction from alga Ulva lactuca.

We investigated structural features of polysaccharides from Ulva lactuca and their effects on the classical models of nociception and inflammation. Crude extract was obtained by enzymatic digestion and isolated by ion exchange chromatography on DEAE-cellulose. The fraction with higher yield was used in the tests (SP-Ul). Swiss mice received SP-Ul (1, 3 or 9mg/kg; i.v.), 30min prior to injection of 0.8%-acetic acid or 1%-formalin or prior to a thermal stimulus. At same doses, SP-Ul was tested on Wistar rats on paw edema elicited by different irritants (carrageenan, dextran, bradykinin, histamine or serotonin). The results of infrared characterization indicated the presence of hydroxyl groups, sulfate, uronic acid and glycosidic linkages in all SP fractions spectrums. SP-Ul decreased significantly the antinociception in response to acetic acid or formalin (second phase), but not in the hot-plate test, suggesting that its analgesia occurs through a peripheral mechanism. SP-Ul did not reduce carrageenan-induced paw edema as supported by both histological and myeloperoxidase activity assessments. However, SP-Ul (1mg/kg; s.c.) reduced dextran-elicited edema, showing vascular anti-inflammatory effect, with bradykinin as major target because it did not reduce histamine- and serotonin-induced paw edemas. Therefore, SP-Ul acts on bradykinin pathway in its antinociceptive and anti-inflammatory responses.

Intracerebroventricular administration of galanin antagonist sustains insulin resistance in adipocytes of type 2 diabetic trained rats.

The aim of this study is to investigate whether galanin (GAL) central receptors are involved in regulation of insulin resistance. To test it, a GAL antagonist, M35 was intracerebroventricularly administrated in trained type 2 diabetic rats. The euglycemic-hyperinsulinemic clamp test was conducted for an index of glucose infusion rates. The epididymal fat pads were processed for determination of glucose uptake and Glucose Transporter 4 (GLUT4) amounts. The Gal mRNA expression levels in hypothalamus were quantitatively assessed too. We found an inhibitory effect of M35 on glucose uptake into adipocytes, Gal mRNA expression levels in hypothalamus, glucose infusion rates in the clamp test and GLUT4 concentration in plasma membranes and total cell membranes of adipocytes. The ratios of GLUT4 contents of the former to the latter in M35 groups were lower. These results suggest a facilitating role for GAL on GLUT4 translocation and insulin sensitivity via its central receptors in rats.

Nucleus raphe pallidus participates in midbrain-medullary cardiovascular sympathoinhibition during electroacupuncture.

We have shown that electroacupuncture (EA) inhibits sympathoexcitatory rostral ventrolateral medulla (rVLM) neurons and reflex responses following activation of a long-loop pathway in the arcuate nucleus and ventrolateral periaqueductal gray (vlPAG). Additionally, EA at P 5-6 acupoints (overlying the median nerve) activates serotonin-containing neurons in the nucleus raphé pallidus (NRP), which, in turn, inhibit rVLM neurons. Although direct projections from the vlPAG to the rVLM exist, it is uncertain whether an indirect pathway through the NRP serves an important role in vlPAG-rVLM cardiovascular modulation. Therefore, the splanchnic nerve (SN) was stimulated to induce cardiovascular sympathoexcitatory reflexes, and EA was applied at P 5-6 acupoints in α-chloralose-anesthetized cats. A single-barreled recording electrode was inserted into the NRP or rVLM. Microinjection of DL-homocysteic acid (DLH) into the vlPAG increased the NRP neuronal response to SN stimulation (5 ± 1 to 12 ± 2 spikes/30 stim). Likewise, EA at P 5-6 for 30 min increased the NRP response to SN stimulation (3 ± 1 to 10 ± 2 spikes/30 stim), an effect that could be blocked by microinjection of kynurenic acid (KYN) into the caudal vlPAG. Furthermore, the reflex increase in blood pressure induced by application of bradykinin to the gallbladder and the rVLM cardiovascular presympathetic neuronal response to SN stimulation was inhibited by injection of DLH into the vlPAG, a response that was reversed by injection of KYN into the NRP. These results indicate that EA activates the vlPAG, which excites the NRP to, in turn, inhibit rVLM presympathetic neurons and reflex cardiovascular sympathoexcitatory responses.

Bradykinin receptors antagonists and nitric oxide synthase inhibitors in vincristine and streptozotocin induced hyperalgesia in chemotherapy and diabetic neuropathy rat model.

PURPOSE: The influence of an irreversible inhibitor of constitutive NO synthase (L-NOArg; 1.0 mg/kg ip), a relatively selective inhibitor of inducible NO synthase (L-NIL; 1.0 mg/kg ip) and a relatively specific inhibitor of neuronal NO synthase (7-NI; 0.1 mg/kg ip), on antihyperalgesic action of selective antagonists of B2 and B1 receptors: D-Arg-[Hyp3,Thi5,D-Tic7,Oic8] bradykinin (HOE 140; 70 nmol/kg ip) or des Arg10 HOE 140 (70 nmol/kg ip) respectively, in model of diabetic (streptozotocin-induced) and toxic (vincristine-induced) neuropathy was investigated. METHODS: The changes in pain thresholds were determined using mechanical stimuli--the modification of the classic paw withdrawal test described by Randall-Selitto. RESULTS: The results of this paper confirm that inhibition of bradykinin receptors and inducible NO synthase but not neuronal NO synthase activity reduces diabetic hyperalgesia. Pretreatment with L-NOArg and L-NIL but not 7-NI, significantly increases antihyperalgesic activity both HOE 140 and des Arg10 HOE 140. It was also shown that both products of inducible NO synthase and neuronal NO synthase activation as well as bradykinin are involved in hyperalgesia produced by vincristine. Moreover, L-NOArg and 7-NI but not L-NIL intensify antihyperalgesic activity of HOE 140 or des-Arg10HOE 140 in toxic neuropathy. CONCLUSIONS: Results of these studies suggest that B1 and B2 receptors are engaged in transmission of nociceptive stimuli in both diabetic and toxic neuropathy. In streptozotocin-induced hyperalgesia, inducible NO synthase participates in pronociceptive activity of bradykinin, whereas in vincristine-induced hyperalgesia bradykinin seemed to activate neuronal NO synthase pathway. Therefore, concomitant administration of small doses of bradykinin receptor antagonists and NO synthase inhibitors can be effective in alleviation of neuropathic pain, even in hospital care.

Triggering of proteinase-activated receptor 4 leads to joint pain and inflammation in mice.

OBJECTIVE: To investigate the role of proteinase-activated receptor 4 (PAR-4) in mediating joint inflammation and pain in mice. METHODS: Knee joint blood flow, edema, and pain sensitivity (as induced by thermal and mechanical stimuli) were assessed in C57BL/6 mice following intraarticular injection of either the selective PAR-4 agonist AYPGKF-NH(2) or the inactive control peptide YAPGKF-NH(2). The mechanism of action of AYPGKF-NH(2) was examined by pretreatment of each mouse with either the PAR-4 antagonist pepducin P4pal-10 or the bradykinin antagonist HOE 140. Finally, the role of PAR-4 in mediating joint inflammation was tested by pretreating mice with acutely inflamed knees with pepducin P4pal-10. RESULTS: PAR-4 activation caused a long-lasting increase in joint blood flow and edema formation, which was not seen following injection of the control peptide. The PAR-4-activating peptide was also found to be pronociceptive in the joint, where it enhanced sensitivity to a noxious thermal stimulus and caused mechanical allodynia and hyperalgesia. The proinflammatory and pronociceptive effects of AYPGKF-NH(2) could be inhibited by pepducin P4pal-10 and HOE 140. Finally, pepducin P4pal-10 ameliorated the clinical and physiologic signs of acute joint inflammation. CONCLUSION: This study demonstrates that local activation of PAR-4 leads to proinflammatory changes in the knee joint that are dependent on the kallikrein-kinin system. We also show for the first time that PARs are involved in the modulation of joint pain, with PAR-4 being pronociceptive in this tissue. Thus, blockade of articular PAR-4 may be a useful means of controlling joint inflammation and pain.

Anti-inflammatory evaluation of Solidago chilensis Meyen in a murine model of pleurisy.

UNLABELLED: The aim of this study was to investigate the anti-inflammatory effects and the mechanism of action of the aqueous extracts obtained from rhizomes, leaves and inflorescences of Solidago chilensis in the mouse model of pleurisy. The extracts were prepared by infusion and were lyophilized. RESULTS: The aqueous extracts of rhizomes, leaves or inflorescences inhibited leukocytes, neutrophils and exudation (P<0.05) in the inflammation induced by carrageenan. The rhizomes aqueous extract, butanolic and aqueous residual fractions inhibited leukocytes, neutrophils, myeloperoxidase, adenosine-deaminase, and tumor necrosis factor alpha levels in the inflammation induced by carrageenan (P<0.05). The rhizome aqueous extract and butanolic fraction also inhibited exudation, nitric oxide, and interleukin-1 beta levels (P<0.05). The rhizomes aqueous extract and its two derived fractions reduced leukocytes and mononuclears in the pleurisy induced by bradykinin, histamine, or substance P (P<0.05) and neutrophils in the pleurisy induced by histamine or substance P (P<0.05). Only aqueous residual fraction inhibited neutrophils induced by bradykinin (P<0.05). CONCLUSION: Solidago chilensis aqueous extracts from leaves, inflorescences and rhizomes demonstrated an important anti-inflammatory effect, inhibiting cells in the inflammation caused by carrageenan. In addition, the rhizomes aqueous extract and its derived fractions also decreased pro-inflammatory mediators release into the site of the inflammatory process. The rhizomes aqueous extract and the butanolic fraction showed more evident anti-inflammatory actions.

Repeated sound stress enhances inflammatory pain in the rat.

While it is well established that acute stress can produce antinociception, a phenomenon referred to as stress-induced analgesia, repeated exposure to stress can have the opposite effect. Since, chronic pain syndromes, such as fibromyalgia and rheumatoid arthritis, may be triggered and/or exacerbated by chronic stress, we have evaluated the effect of repeated stress on mechanical nociceptive threshold and inflammatory hyperalgesia. Using the Randall-Selitto paw pressure test to quantify nociceptive threshold in the rat, we found that repeated non-habituating sound stress enhanced the mechanical hyperalgesia induced by the potent inflammatory mediator, bradykinin, which, in normal rats, produces hyperalgesia indirectly by stimulating the release of prostaglandin E2 from sympathetic nerve terminals. Hyperalgesia induced by the direct-acting inflammatory mediator, prostaglandin E2 as well as the baseline nociceptive threshold, were not affected. Adrenal medullectomy or denervation, reversed the effect of sound stress. In sound stressed animals, bradykinin-hyperalgesia had a more rapid latency to onset and was no longer inhibited by sympathectomy, compatible with a direct effect of bradykinin on primary afferent nociceptors. In addition, implants of epinephrine restored bradykinin-hyperalgesia in sympathectomized non-stressed rats, lending further support to the suggestion that increased plasma levels of epinephrine can sensitize primary afferents to bradykinin. These results suggest that stress-induced enhancement of inflammatory hyperalgesia is associated with a change in mechanism by which bradykinin induces hyperalgesia, from being sympathetically mediated to being sympathetically independent. This sympathetic-independent enhancement of mechanical hyperalgesia is mediated by the stress-induced release of epinephrine from the adrenal medulla.

Intrathecal gabapentin enhances the analgesic effects of subtherapeutic dose morphine in a rat experimental pancreatitis model.

BACKGROUND: Morphine sulfate has long been used for analgesia, but clinical applications can be limited by side effects, tolerance, and potential for addiction at therapeutic doses. An agent that produces therapeutic analgesia when coadministered with low-dose morphine could have important clinical uses. The anticonvulsant agent gabapentin has been identified as having antihyperalgesic properties acting on the alpha2delta1 subunit of N-type voltage-activated calcium channels on dorsal root ganglia neurons. In this study, intrathecal gabapentin, which by itself is ineffective when administered spinally, was combined with low-dose morphine and tested in an acute bradykinin-induced pancreatitis model in rats. METHODS: An intrathecal catheter was surgically inserted into the subarachnoid space of male Sprague-Dawley rats. A laparotomy was performed for ligation and cannulation of the bile-pancreatic duct. Rats were pretreated intrathecally with artificial cerebrospinal fluid, gabapentin, morphine, or combined gabapentin and morphine 30 min before bradykinin injection into the bile-pancreatic duct. Spontaneous behavioral activity (cage crossing, rearing, and hind limb extension) was monitored before drug injection (baseline) and after bradykinin injection into the bile-pancreatic duct to assess visceral pain. RESULTS: Spinal pretreatment with up to 300 microg gabapentin alone was not effective in reducing hind limb extension in this model, but did restore some cage crossing and rearing behaviors. Spinal treatment with low-dose morphine reduced hind limb extension only. Spinal pretreatment with combined gabapentin and subtherapeutic doses of morphine sulfate resulted in restoration of all spontaneous behaviors to surgical baseline levels including elimination of hind limb extension. CONCLUSION: Combined spinal administration of gabapentin and low doses of morphine significantly reduces pain-related behaviors in this acute rat pancreatitis model, whereas these agents were ineffective when used alone in this dose range. These data suggest that the alpha2delta1 subunit of the N-type voltage-activated Ca2+ channels is involved in transmission of this visceral pain, likely through effects on primary afferent endings in the spinal cord. Thus, gabapentin may be an effective adjuvant to initial low dose spinal opioid therapy for clinical management of visceral pain.

Bradykinin receptor antagonism and endothelial tissue plasminogen activator release in humans.

OBJECTIVE: We sought to assess pharmacodynamic responses to the bradykinin antagonist B9340 and to determine the contribution of the endothelial bradykinin receptor to stimulated tissue plasminogen activator (t-PA) release in humans. METHODS AND RESULTS: Bilateral forearm blood flow and plasma fibrinolytic variables were measured in 8 volunteers during 100 minutes of intrabrachial infusions of saline placebo, B9340 at 4.5 nmol/min, or B9340 at 13.5 nmol/min. On each occasion, intra-arterial bradykinin (30 to 3000 pmol/min) and substance P (4 to 16 pmol/min) were coinfused for 10 minutes at each dose. To assess the onset and offset of action, 6 additional subjects on 2 occasions received intra-arterial bradykinin (100 pmol/min) for 60 minutes with a coinfusion of either saline placebo or B9340 (13.5 nmol/min) for 12 minutes. During placebo infusion, bradykinin and substance P caused dose-dependent vasodilatation in the infused forearm (P<0.001). B9340 caused a dose-dependent inhibition of bradykinin-induced forearm vasodilatation and t-PA release (P<0.001) without affecting substance P-induced vasodilatation or t-PA release (P=NS). B9340 caused a reversible inhibition of bradykinin-induced vasodilatation (P<0.001) with a rapid onset and offset of action. CONCLUSIONS: B9340 is a potent, reversible, and selective competitive receptor antagonist of bradykinin-induced vasodilatation and t-PA release in humans.

Modulation of cutaneous inflammation by angiotensin-converting enzyme.

Cutaneous neurogenic inflammation is a complex biological response of the host immune system to noxious stimuli. Present evidence suggests that zinc metalloproteases may play an important role in the regulation of neurogenic inflammation by controlling the local availability of neuropeptides, such as substance P (SP), that are capable of initiating or amplifying cutaneous inflammation after release from sensory nerves. To address the hypothesis that the dipeptidyl carboxypeptidase angiotensin-converting enzyme (ACE) is capable of modulating skin inflammation, we have analyzed murine allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD) using wild-type C57BL/6J (ACE(+/+)) or genetically engineered mice with a heterozygous deletion of somatic ACE (ACE(+/-)). In 2,4-dinitro-1-fluorobenzene-sensitized ACE(+/-) mice, ACD was significantly augmented in comparison to ACE(+/+) controls as determined by the degree of ear swelling after exposure to hapten. Likewise, systemic treatment of ACE(+/+) mice with the ACE inhibitor captopril before sensitization or elicitation of ACD significantly augmented the ACD response. In contrast, local damage and neuropeptide depletion of sensory nerves following capsaicin, injection of a bradykinin B(2), or a SP receptor antagonist before sensitization significantly inhibited the augmented effector phase of ACD in mice with functionally absent ACE. However, in contrast to ACD, the response to the irritant croton oil was not significantly altered in ACE(+/-) compared with ACE(+/+) mice. Thus, ACE by degrading bradykinin and SP significantly controls cutaneous inflammatory responses to allergens but not to irritants, which may explain the frequently observed exacerbation of inflammatory skin disease in patients under medication with ACE inhibitors.

Anti-inflammatory effect of synthetic somatostatin analogues in the rat.

1. Somatostatin (6.11 nmol kg(-1) i.p.) inhibited neurogenic plasma extravasation evoked by 1% mustard oil and non-neurogenic oedema induced by 5% dextran in the rat skin. 2. Cyclic synthetic octapeptide (TT-248 and TT-250) and heptapeptide (TT-232) somatostatin analogues proved to be more effective in reducing neurogenic and non-neurogenic inflammatory reactions but octreotide had no influence on either neurogenic or non-neurogenic inflammation. 3. TT-232 administered i.p. or i.v. (1.06 - 42.40 nmol kg(-1)) inhibited in a dose-dependent manner the plasma extravasation evoked by mustard oil in the rat's paw. Neither diclofenac (15.78 - 315.60 micromol kg(-1)) nor the selective COX-2 inhibitor meloxicam (2.95 - 569.38 micromol kg(-1)) attenuated the mustard oil-induced neurogenic plasma extravasation. 4. TT-232, diclofenac and meloxicam dose-dependently diminished non-neurogenic dextran-oedema of the paw the ED(35) values were 1.73 nmol kg(-1) for TT-232 and 34.37 micromol kg(-1) for diclofenac. 5. TT-232 inhibited in the dose range of 1.06 - 21.21 nmol kg(-1) the bradykinin-induced plasma extravasation in the skin of the chronically denervated paw. 6. Mustard oil-induced cutaneous plasma extravasation was dose-dependently diminished by s.c. TT-232 1, 2, 4, 6 or 16 h after the treatment. TT-232 (2 x 106, 2 x 212 and 2 x 530 nmol kg(-1) per day s.c. for 18 days) caused dose-dependent inhibition of chronic Freund adjuvant-induced arthritis during the experimental period. 7. TT-232 (200 and 500 nM) inhibited the release of SP, CGRP and somatostatin from the rat isolated trachea induced by electrical field stimulation (40 V, 0.1 ms, 10 Hz, 120 s) or by capsaicin (10(-7) M), but did not influence the basal, non-stimulated peptide release. 8. It is concluded that somatostatin analogues without endocrine functions as TT-232 are promising compounds with a novel site of action for inhibition of non-neurogenic and neurogenic inflammatory processes.

Sensory pathways and cyclooxygenase regulate mucus gel thickness in rat duodenum.

We previously showed that the duodenal hyperemic response to acid occurs through activation of capsaicin-sensitive afferent nerves with subsequent release of vasodilatory substances such as calcitonin gene-related peptide (CGRP) and nitric oxide. We then tested the hypothesis that similar factors regulate duodenal mucus gel thickness. Gel thickness was optically measured using in vivo microscopy in anesthetized rats. Duodenal mucosae were superfused with pH 7.0 buffer with vanilloid receptor agonist capsaicin, bradykinin, or PGE(2) injection or were challenged with pH 2.2 solution, with or without the vanilloid antagonist capsazepine, human CGRP-(8-37), N(G)-nitro-L-arginine methyl ester, and indomethacin. Other rats underwent sensory ablation with high-dose capsaicin pretreatment. Acid, bradykinin, capsaicin, and PGE(2) all quickly thickened the gel. Antagonism of vanilloid and CGRP receptors, inhibition of nitric oxide synthase, and sensory deafferentation delayed gel thickening, suggesting that the capsaicin pathway mediated the initial burst of mucus secretion that thickened the gel. Indomethacin abolished gel thickening due to acid, bradykinin, and capsaicin. Inhibition of gel thickening by indomethacin in response to multiple agonists suggests that cyclooxygenase activity is essential for duodenal gel thickness regulation. Duodenal afferent neural pathways play an important role in the modulation of cyclooxygenase-mediated physiological control of gel thickness.

Effects of chondroitin sulfate-C on bradykinin-induced proteoglycan depletion in rats.

Depletion of the proteoglycan content of articular cartilage was induced by injecting bradykinin (30-300 mumol/l, 50 microliters/knee) into the left knee articular cavities of rats 3 times a day for 2 days. The degree of the reduction in the intensity of histopathological safranin O staining was used as an index of proteoglycan depletion. Bradykinin reduced the cartilage proteoglycan contents of the knee joints of non-injected limbs in a dose-dependent manner and at 300 mumol/l markedly reduced these contents, but evoked no inflammatory changes. The extent of the reduction of the cartilage proteoglycan contents induced by bradykinin injection depended on the dose and injection frequency. Chondroitin sulfate-C (CAS 25322-46-7, Chondroitin ZS Tab) (30-1,000 mg/kg/day) administered orally to rats for 14 days inhibited the bradykinin-induced proteoglycan depletion of the articular cartilage in a dose-dependent manner. These results suggest that a reduction of the proteoglycan content of cartilage, like that associated with osteoarthritis, was induced by injecting bradykinin into the knee articular cavities of rats and chondroitin sulfate-C protected against this effect.

Concentration-dependent effects of bradykinin on leukocyte recruitment and venular hemodynamics in rat mesentery.

The results of several recent studies indicate that bradykinin protects tissues against the deleterious effects of ischemia-reperfusion (I/R). However, other studies indicate that bradykinin can act as a proinflammatory agent, inducing P-selectin expression, the formation of chemotactic stimuli, and endothelial barrier disruption. In the present study, we used intravital microscopic techniques to examine the dose-dependent effects of bradykinin on leukocyte-endothelial cell interactions, the formation of platelet-leukocyte aggregates, and venular hemodynamics in rat mesentery in an attempt to explain these divergent findings. Superfusion of the mesentery with low concentrations of bradykinin (/=10(-6) M) decreased V(RBC), increased the number of platelet-leukocyte aggregates, and induced leukocyte adhesion in single postcapillary venules. The formation of platelet-leukocyte aggregates and increased leukocyte adhesion induced by high-dose bradykinin were attenuated by administration of a B(2)-receptor (HOE-140) or a platelet-activating factor (PAF, WEB-2086) antagonist. Thus these adhesive interactions induced by high-dose bradykinin appear to be mediated by a mechanism that is dependent on B(2)-receptor activation and the formation of PAF or PAF-like lipids. The effects of bradykinin on venular V(RBC) and blood flow were also concentration dependent, with low doses producing nitric oxide-mediated vasodilation, whereas high doses decreased V(RBC) by a mechanism that is PAF independent.

Chronic bradykinin infusion and receptor blockade in angiotensin II hypertension in rats.

The influence of endogenous bradykinin(BK) on the control of arterial pressure and the development of cardiac hypertrophy was assessed in chronically angiotensin II(Ang II)-infused rats (200 ng. kg-1. min-1) through the effects of concomitant infusion of 3 doses of BK (15 ng. kg-1. d-1, 100 ng. kg-1. d-1 and 100 ng. kg-1. min-1 ie, 144 000 ng. kg-1. d-1) or BK-blockade by Hoe140 (300 microg. kg-1. d-1) for 10 days. In Ang II-infused rats, tail-cuff pressure increased from 124+/-3 to 174+/-6 mm Hg (P<0.001). The pressor effect of Ang II was not affected by simultaneous infusion of BK or Hoe140. At the end of the experiments, cardiac mass was higher in rats infused with Ang II alone (3.56+/-0.10 versus 2.89+/-0.05 mg/g in untreated controls, P<0.01) and the development of cardiac hypertrophy was not modified by administration of the 3 doses of BK or Hoe140. In addition, the fall in cardiac output associated with Ang II was prevented only by the moderate and high doses of BK, mainly through an increase in stroke volume and a decrease in total peripheral resistance. In the same way, the renal vasoconstrictor effect of Ang II was abolished by the medium and high dose of BK. Hoe140 did not affect cardiac output or renal blood flow in this model. No influence of BK or Hoe140 on the increase in albuminuria induced by Ang II was detected. In conclusion, exogenous BK may oppose the effect of Ang II on vascular tone, but it cannot prevent hypertension and target-organ damage associated with this experimental model of hypertension, even at a very high dose.

Vespula vulgaris venom: role of kinins and release of 5-hydroxytryptamine from skin mast cells.

Wasp venoms contain several active components, among them kinin-related peptides. Like bradykinin and [Thr6]bradykinin, Vespula vulgaris venom caused paw oedema following subplantar injection in anaesthetized rats. The oedema was partly inhibited by the bradykinin B2 receptor antagonist icatibant (Hoe 140); the remaining part was abolished by additional pretreatment with 5-hydroxytryptamine (5-HT) receptor antagonists or mast cell depletion. Histamine receptor antagonists were ineffective. Capsaicin pretreatment attenuated oedema formation indicating a neurogenic sensory component. Nociceptive behavioural responses induced by the venom in unanaesthetized rats were abolished by icatibant. It is concluded that kinins, either contained in the venom or released from the tissue, play the predominant role in the inflammatory and algesic effects. The inflammatory effects only partly rely on direct, bradykinin receptor-mediated mechanisms while the remaining part depends on the release of 5-HT from skin mast cells. The algesic effects of the venom are entirely due to direct B2 receptor activation.

[The effect of bradykinin, vasopressin and ACTH (4-10) on the morphine withdrawal syndrome in morphine-dependent rats of 2 inbred strains]. / Vliianie bradikinina, vazopressina i AKTG(4--10) na sindrom otmeny morfina u morfin-zavisimykh krys dvukh inbrednykh linii.

The effect of intranasal administration of bradykinin, ACTH(4-10) fragment, and vasopressin on the withdrawal syndrome was studied in morphine-dependent rats of two inbred strains, WAG/G and Fischer-344. Morphine dependence was stronger and the withdrawal syndrome had a more severe course in WAG/G rats. Intranasal administration of bradykinin and the ACTH(4-10) fragment in the dose used had no effect on the expression of the withdrawal syndrome in rats of both strains. Intranasal administration of vasopressin intensified the withdrawal syndrome in Fischer-344 rats but not in WAG-G rats. It may thus be supposed that the genetic differences in the level of endogenous vasopressin or the sensitivity of its receptors are related to the resistance to morphine dependence formation. These data, however, are of a preliminary character and study of their mechanisms will be the purpose of further research.

Amlodipine and benazeprilat differently affect the responses to endothelin-1 and bradykinin in porcine ciliary arteries: effects of a low and high dose combination.

PURPOSE: Visual field defects caused by vasospasm are often encountered in ophthalmology as a feature of glaucoma with poor response to conventional treatment. Combination therapy with drugs acting via different mechanisms might be more effective. Therefore, the effects of the calcium antagonist amlodipine and the angiotensin converting enzyme (ACE) inhibitor benazeprilat at low and high dose combination on contractions to endothelin-1 and endothelium-dependent relaxations to bradykinin were examined in porcine ciliary arteries. METHODS: Segments of the arteries were suspended in myographs for isometric tension recording. RESULTS: Pretreatment of the vessels with either amlodipine, the low or high dose combination significantly reduced the sensitivity to endothelin-1 as compared to control (concentration shift 18.3-fold, 14.2-fold, 23.3-fold respectively; p < 0.05), while benazeprilat was ineffective. The maximal response to endothelin-1 (10(-7) M) was most inhibited by the high dose combination which reduced the contractions by 49% as compared to control (p < 0.05). The low dose combination and amlodipine alone were less effective (reduction: 25%; p < 0.05 and 20%; n.s., respectively). On the other hand, benazeprilat enhanced the sensitivity (concentration shift 73-fold; p < 0.05) and maximal relaxation to bradykinin (by 27%; p < 0.01), whereas amlodipine or the low or high dose combination were ineffective. CONCLUSIONS: These findings indicate that amlodipine and benazeprilat differently affect vascular function of ciliary arteries. A high dose combination of both substances was most effective in inhibiting contractions to endothelin-1, suggesting a potentiating effect of the two compounds. In contrast, endothelium-dependent relaxations to bradykinin were enhanced by benazeprilat alone, but not when combined with amlodipine.

Inhibition by actinomycin D of neurogenic mouse ear oedema.

We have investigated the effects of actinomycin D on mouse ear oedema induced by capsaicin, neuropeptides, and established inflammatory mediators. Actinomycin D (0.5 mg/kg, i.v.) significantly (P < 0.01) inhibited ear oedema induced by topical application of capsaicin, while adriamycin (6.0 mg/kg, i.v.) and cycloheximide (6.0 mg/kg, i.v.) had no effect on oedema. The ear oedema induced by intradermal injection of neuropeptides such as mammalian tachykinins, calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP), was markedly (P < 0.05, P < 0.01 or P < 0.001) suppressed by actinomycin D. The drug was also effective (P < 0.01 or P < 0.001) in inhibiting bradykinin (BK)- and compound 48/80-induced ear oedema, but did not inhibit oedema induced by histamine, 5-HT, leukotriene C4 (LTC4), and platelet activating factor (PAF) at a dose of 1 mg/kg. In mast cell-deficient W/WV mice, actinomycin D (1.0 mg/kg, i.v.) failed to inhibit substance P (SP)-induced ear oedema whereas spantide (0.5 mg/kg, i.v.) was an effective (P < 0.01) inhibitor of oedema formation. Furthermore, actinomycin D (10-100 microM) dose-dependently prevented histamine release from rat peritoneal mast cells evoked by SP, compound 48/80, and the ionophore A23182, respectively. These results strongly suggest that an inhibitory effect of actinomycin D on neurogenic inflammation is due primarily to the prevention of mast cell activation mediated by neuropeptides, rather than an interaction with DNA or receptors of neuropeptides.

Inhibition of hind-paw edema and cutaneous vascular plasma extravasation in mice by acetylshikonin.

Acetylshikonin, a naphthoquinone isolated from the Chinese herb medicine, tzu ts'ao, was demonstrated to inhibit the polymyxin B-induced hind-paw edema in normal as well as in adrenalectomized mice. Liver glycogen content was increased in adrenalectomized mice pretreated with dexamethasone, but not with acetylshikonin. Like diphenhydramine, methysergide and isoproterenol, acetylshikonin reduced the plasma exudation evoked in dorsal hind-paw skin by antidromic stimulation of the saphenous nerve, and in passive cutaneous anaphylactic reaction, bradykinin-, substance P-, compound 48/80-, histamine- and serotonin-induced ear edema. Indomethacin was ineffective in these respects. Bradykinin- and substance P-induced plasma exudation were also significantly reduced when [Thi5,8,D-Phe7]bradykinin and [D-Pro2,D-Trp7,9]substance P were coinjected with bradykinin and substance P, respectively. In isolated rat peritoneal mast cell preparation, acetylshikonin produced a concentration-dependent inhibition of histamine and beta-glucuronidase release from mast cells challenged by compound 48/80. In compound 48/80-pretreated mice, acetylshikonin and isoproterenol produced significantly more inhibitory effect on bradykinin- and substance P-induced plasma exudation than did diphenhydramine in combination with methysergide. Pretreatment with diphenhydramine/methysergide in compound 48/80-pretreated mice significantly further reduced the bradykinin- and substance P-induced plasma exudation if [Thi5,8,D-Phe7]bradykinin and [D-Pro2,D-Trp7,9]substance P were coinjected with bradykinin or substance P, respectively. The results suggest that the inhibitory effect of acetylshikonin on the edematous response is due neither to the release of steroid hormones from the adrenal gland nor to the glucocorticoid activity, but probably partly to the suppression of mast cell degranulation and partly to protection of the vasculature from mediator challenge.