Ameliorative effects of 3,4-oxo-isopropylidene-shikimic acid on experimental colitis and their mechanisms in rats

The aim of the present study was to investigate the therapeutic effect and mechanism of 3,4-oxo-isopropylidene-shikimic acid (ISA) on 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats. (50, 100, 200 mg/kg) was administered for 14 days, 1 day after the induction of colitis by TNBS. The colonic injury and inflammation were assessed by macroscopic damage scores and myeloperoxidase (MPO) activity. Malondialdehyde (MDA) and nitric oxide (NO) levels, and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in plasma were measured with biochemical methods. Prostaglandin E₂ (PGE₂) level in colon was determined by radioimmunoassay. Expressions of inducible nitric oxide synthase (iNOS), cyclo-oxygenase-2 (COX-2), inhibitor kappa B-alpha (IκBα) and nuclear factor kappa B (NF-κB) p65 proteins in the colonic tissue were detected with immunohistochemistry. Enhanced colonic mucosal injury, inflammatory response and oxidative stress were observed in the animals clystered with TNBS, which was manifested as the significant increase in colon mucosal damage index, MPO activity, levels of MDA, NO and PGE₂, as well as the expressions of iNOS, COX-2 and NF-κB p65 proteins in the colonic mucosa, and the significant decrease in expressions of IκBα proteins in the colonic mucosa. However, these parameters were found to be significantly ameliorated in rats treated with ISA at given doses, especially at 100 mg/kg and 200 mg/kg. Administration of ISA may have significant therapeutic effects on experimental colitis in rats, probably due to its mechanism of antioxidation, its inhibition of arachidonic acid metabolism and its modulation of the IκBα/NF-κB p65 expression.     

Concentrated grape juice (G8000™) reduces immunoexpression of iNOS,TNF-alpha,COX-2 and DNA damage on 2,4,6-trinitrobenzene sulfonic acid-induced-colitis

Inflammatory bowel disease (IBD) is a common chronic gastrointestinal disorder characterized by alternating periods of remission and active intestinal inflammation. Flavonoids exert several biological activities, which are mainly related to their ability to inhibit inflammatory process and/or to their antioxidant properties, and are able to regulate the immune response. The aim of this study was to evaluate whether phenolic compounds present in grape juice could reduce the inflammatory effects induced by experimental colitis. A total of 41 male Wistar rats were randomized into seven groups, as follows: G1 – Sham group: sham induced-colitis rats; G2 – (2,4,6-rinitrobenzenesulfonic acid) TNBS group: nontreated induced-colitis; G3 – 2% grape juice control group; G4 – 1% grape juice 24 h after TNBS colitis induction; G5 – 1% grape juice on day 7after colitis induction; G6 – 2% grape juice 24 h after colitis induction; G7 – 2% grape juice on day 7 after colitis induction. Genotoxicity was evaluated by comet assay. Immunohistochemistry was determined using the streptavidin–biotin-peroxidase method being analyzed in control (normal tissue) and “hot spot” areas i.e., presenting inflammatory process being graded as 1 (weak), 2 (moderate), or 3 (strong). Both parameters were evaluated in the cytoplasm of epithelial or inflammatory cells. TNF-immunoexpression and iNOS were reduced after drinking grape juice 24 h or after 7 days for all doses tested. COX-2 was reduced in the groups exposed to 1% grape juice 24 h or 7 days of exposure. The grape juice at 1% dose in the last 7 days of treatment as well as grape juice at 2% dose decreased the peripheral blood genotoxicity. Taken together, the grape juice mainly at 1% dose exerts anti-inflammatory effects in chronic colitis caused by TNBS as a result of down regulation in the expression of pro-inflammatory cytokines and reduction of genotoxicity in peripheral blood cells.     

Protective effect of Lactobacillus plantarum 21, a probiotic on trinitrobenzenesulfonic acid-induced ulcerative colitis in rats

Inflammatory mediators play a crucial role in ulcerative colitis (UC). The present study was aimed to evaluate the effects of Lactobacillus plantarum 21 (LAB 21) on inflammatory mediators in trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats. The inflammatory response was assessed by changes in colon morphology, histopathology, and measurement of reduced glutathione (GSH), lipid peroxidation (TBARS), nitric oxide (NO), interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and interleukin 10 (IL-10) mRNA and protein levels by ELISA. Besides, protein expressions of IL-1β and IL-10 were also evaluated by western blot. Treatment with LAB 21 (1 × 10¹⁰ CFU/rat/day) and sulfasalazine (500 mg kg^− 1 body weight) for 14 days after induction of colitis, significantly decreased TBARS, NO and increased GSH concentration. The protein and mRNA expressions of IL-1β and TNFα were down-regulated, whereas, protein and mRNA expression of IL-10 was up-regulated in LAB 21-treated rats. Moreover, LAB 21 attenuated the macroscopic colonic damage, histopathological changes induced by TNBS. These results suggest that LAB 21 may be effective in the treatment of UC by immunomodulatory and antioxidant properties.     

Novel orally available salvinorin A analog PR-38 protects against experimental colitis and reduces abdominal pain in mice by interaction with opioid and cannabinoid receptors

BackgroundSalvinorin A (SA) is a potent anti-inflammatory diterpene isolated from the Mexican plant S. divinorum. Recently we showed that the novel SA analog, PR-38 has an inhibitory effect on mouse gastrointestinal (GI) motility mediated by opioid and cannabinoid (CB) receptors. The aim of the study was to characterize possible anti-inflammatory and antinociceptive action of PR-38 in the mouse GI tract.MethodsMacro- and microscopic colonic damage scores and myeloperoxidase activity were determined after intraperitoneal (i.p.), intracolonic (i.c.), and per os (p.o.) administration of PR-38 in the trinitrobenzene sulfonic acid (TNBS) and dextran sodium sulfate (DSS) models of colitis in mice. Additionally, MOP, KOP and CB1 protein expression was determined using Western blot analysis of mouse colon samples. The antinociceptive effect of PR-38 was examined based on the number of behavioral responses to i.c. instillation of mustard oil (MO).ResultsThe i.p. (10 mg/kg, twice daily), i.c. (10 mg/kg, twice daily) and p.o. (20 mg/kg, once daily) administration of PR-38 significantly attenuated TNBS- and DSS-induced colitis in mice. The effect of PR-38 was partially blocked by the KOP antagonist nor-binaltorphimine and CB1 antagonist AM 251. Western blot analysis showed a significant increase of MOP, KOP and CB1 receptor expression during colonic inflammation, which was reversed to the control levels by the administration of PR-38. PR-38 significantly decreased the number of pain responses after i.c. instillation of MO in the TNBS-treated mice.ConclusionsOur results suggest that PR-38 has the potential to become a valuable anti-inflammatory and analgesic therapeutic for the treatment of GI inflammation.     

Transient receptor potential vanilloid 1 and transient receptor potential ankyrin 1 contribute to the progression of colonic inflammation in dextran sulfate sodium-induced colitis in mice: Links to calcitonin gene-related peptide and substance P

Transient receptor potential (TRP) vanilloid 1 (TRPV1) and TRP ankyrin 1 (TRPA1), which are non-selective cation channels, play important roles in the sensation of pain. This study investigated the roles of TRPV1 and TRPA1 in dextran sulfate sodium (DSS)-induced murine colitis. DSS (2%) administered for 7 days caused severe colitis that was significantly less severe in TRPV1-deficient (TRPV1KO) and TRPA1-deficient (TRPA1KO) mice than that in wild-type (WT) mice. Similar colitis attenuations were observed in TRPV1KO and TRPA1KO mice but not in WT mice that had been transplanted with bone marrow cells from WT, TRPA1KO, or TRPV1KO mice. DSS treatment upregulated calcitonin gene-relative peptide (CGRP)- and substance P (SP)-positive nerve fibers in the colonic mucosa of WT mice. TRPV1KO and TRPA1KO mice showed significant reductions in the DSS-induced upregulation of SP, but the DSS-induced upregulation of CGRP was not reduced. Sensory deafferentation evoked by pretreatment with high doses of capsaicin markedly exacerbated DSS-induced colitis with reductions in DSS-induced upregulation of SP- and CGRP-positive nerve fibers. These findings suggest that neuronal TRPV1 and TRPA1 contribute to the progression of colonic inflammation. While these responses may be mediated by the upregulation of SP-mediated deleterious mechanisms, CGRP may be associated with protective mechanisms.     

Dose-dependent antiinflammatory effect of ursodeoxycholic acid in experimental colitis

The denomination of inflammatory bowel disease comprises a group of chronic inflammatory diseases of the digestive tract, ulcerative colitis and Crohn's disease being the most important conditions. Bile acids may play a role both in etiology and pharmacology of this disease. Thus, although deoxycholic acid is regarded as a proinflammatory agent ursodeoxycholic acid, which is currently being used to treat certain types of cholestasis and primary biliary cirrhosis, because of their choleretic, cytoprotective and immunomodulatory effects, it has been reported to exert an anti-inflammatory activity. We aim to confirm and characterize the intestinal antiinflammatory activity of ursodeoxycholic acid. The experimental model trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats has been used. Animal status was characterized by a number of macroscopic and biochemical parameters. Oral administration of ursodeoxycholic acid was able to ameliorate experimental colonic inflammation. This occurred only at a relatively high dose (50 mg/kg day), whereas ursodeoxycholic acid was without significant effect at doses of 10 and 25 mg/kg day. The therapeutic effect was evidenced, among others, by a higher body weight recovery, a diminished affected to total mucosal area and lower alkaline phosphatase activity in treated vs. control (TNBS treated) animals. These results indicate that, at the appropriate dose, ursodeoxycholic acid is a potentially useful drug to reduce intestinal inflammation and could be envisaged to be incorporated in the treatment of inflammatory bowel diseases.     

Role of TRPV1 and ASIC3 in formalin-induced secondary allodynia and hyperalgesia

BackgroundIn the present study we determined the role of transient receptor potential V1 channel (TRPV1) and acid-sensing ion channel 3 (ASIC3) in chronic nociception.Methods1% formalin was used to produce long-lasting secondary allodynia and hyperalgesia in rats. Western blot was used to determine TRPV1 and ASIC3 expression in dorsal root ganglia.ResultsPeripheral ipsilateral, but not contralateral, pre-treatment (−10 min) with the TRPV1 receptor antagonists capsazepine (0.03–0.3 μM/paw) and A-784168 (0.01–1 μM/paw) prevented 1% formalin-induced secondary mechanical allodynia and hyperalgesia in the ipsilateral and contralateral paws. Likewise, peripheral ipsilateral, but not contralateral, pre-treatment with the non-selective and selective ASIC3 blocker benzamil (0.1–10 μM/paw) and APETx2 (0.02–2 μM/paw), respectively, prevented 1% formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. Peripheral ipsilateral post-treatment (day 6 after formalin injection) with capsazepine (0.03–0.3 μM/paw) and A-784168 (0.01–1 μM/paw) reversed 1% formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. In addition, peripheral ipsilateral post-treatment with benzamil (0.1–10 μM/paw) and APETx2 (0.02–2 μM/paw), respectively, reversed 1% formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. TRPV1 and ASIC3 proteins were expressed in dorsal root ganglion in normal conditions, and 1% formalin injection increased expression of both proteins in this location at 1 and 6 days compared to naive rats.ConclusionsData suggest that TRPV1 and ASIC3 participate in the development and maintenance of long-lasting secondary allodynia and hyperalgesia induced by formalin in rats. The use of TRPV1 and ASIC3 antagonists by peripheral administration could prove useful to treat chronic pain.     

The role of transient receptor potential ankyrin 1 (TRPA1) receptor activation in hydrogen-sulphide-induced CGRP-release and vasodilation

Activation of transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) channels on capsaicin-sensitive sensory neurons causes release of inflammatory neuropeptides, including calcitonin gene-related peptide (CGRP). We investigated whether the hydrogen sulphide (H(2)S)-evoked CGRP release from sensory neurons of isolated rat tracheae and H(2)S-induced increases in the microcirculation of the mouse ear were mediated by TRPA1 receptor activation. Allylisothiocyanate (AITC) or the H(2)S donor sodium hydrogen sulphide (NaHS) were used as stimuli and CGRP release of the rat tracheae was measured by radioimmunoassay. AITC or NaHS were applied to the ears of Balb/c, C57BL/6, TRPA1 and TRPV1 receptor gene knockout mice and blood flow was detected by laser Doppler imaging. Both AITC and NaHS increased CGRP release from isolated rat tracheae, and both responses were inhibited by the TRPA1 antagonist, HC-030031, but was not affected by the TRPV1 receptor blocker, BCTC. Application of AITC or NaHS increased the cutaneous blood flow in the mouse ears. Similarly to the effect of AITC, the vasodilatory response to NaHS was reduced by HC-030031 or in TRPA1 deleted mice. In contrast, genetic deletion of TRPV1 did not affect the increase in the ear blood flow evoked by AITC or NaHS. We conclude that H(2)S activates TRPA1 receptors causing CGRP release from sensory nerves of rat tracheae, as well as inducing cutaneous vasodilatation in the mouse ear. TRPV1 receptors were not involved in these processes. Our results highlight that TRPA1 receptor activation should be considered as a potential mechanism of vasoactive effects of H(2)S.     

Differential involvement of TRPV1 receptors at the central and peripheral nerves in CFA-induced mechanical and thermal hyperalgesia

Transient receptor potential vanilloid 1 (TRPV1) antagonists are known to attenuate two typical symptoms of inflammatory hyperalgesia: thermal and mechanical. However, it is not clear whether the sites of participation of TRPV1 for each symptom are different. In this study, we clarified the difference between the site of TRPV1 involvement in both symptoms by analysing the anti-hyperalgesic activity of two kinds of TRPV1 antagonists given locally (i.e. intraplantarly and intrathecally) in rats with CFA (complete Freund's adjuvant)-induced inflammation. TRPV1 antagonists BCTC (N-(4-tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl) tetrahydropyrazine-1(2H)-carbox-amide, 1-300 microg) and SB-366791 (N-(3-methoxyphenyl)-4-chlorocinnamide, 30-300 microg) administered intraplantarly in a dose-dependent manner inhibited CFA-induced thermal hyperalgesia. In addition, CFA-induced thermal hyperalgesia was significantly reversed by intrathecal administration of 1-100 microg of BCTC and SB-366791. While intraplantar BCTC (1-300 microg) and SB-366791 (30-300 microg) did not reverse CFA-induced mechanical hyperalgesia, 1-100 microg of intrathecally administered BCTC and SB-366791 dose-dependently reduced mechanical hyperalgesia. Regression analysis showed that a correlation exists between the inhibitory effects on thermal hyperalgesia and mechanical hyperalgesia after intrathecal administration (correlation factor = 0.6521), but not after intraplantar administration (correlation factor = 0.0215). These data suggest that TRPV1 in the peripheral endings of the primary afferents plays a key role in thermal hyperalgesia, but it makes only a minor contribution in CFA-induced mechanical hyperalgesia. Furthermore, it is suggested that the spinal TRPV1 is critical in the development of both types of hyperalgesia.     

The effects of konjac oligosaccharide on TNBS-induced colitis in rats

The purpose of the study was to assess the effects and the protective mechanism of konjac oligosaccharide (KOS) on the ulcerative colitis (UC) model induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats. KOS (1.0 and 4.0 g/kg/day) was administered for 14 days after the induction of colitis with TNBS. The status of the rats was assessed by morphological and biochemical methods. The effect of KOS on the colonic microflora was also assessed by studying the bacteria profile and short chain fatty acids (SCFAs) production in feces by standard culture techniques and gas chromatography, respectively. KOS administration improved rat weight, colonic length, damage score, structure of gut microbiota, production of SCFA, and reduced colon tissue levels of malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β). Therefore, our results indicate that KOS is an anti-inflammatory and could be useful as a prebiotic to design functional foods for UC.     

Heteromeric TRPV4/TRPC1 channels mediate calcium-sensing receptor-induced nitric oxide production and vasorelaxation in rabbit mesenteric arteries

Stimulation of calcium-sensing receptors (CaSR) by increasing the external calcium concentration (Ca^2 +]_o) induces endothelium-dependent vasorelaxation through nitric oxide (NO) production and activation of intermediate Ca^2 +-activated K⁺ currents (IK_Ca) channels in rabbit mesenteric arteries. The present study investigates the potential role of heteromeric TRPV4-TRPC1 channels in mediating these CaSR-induced vascular responses. Immunocytochemical and proximity ligation assays showed that TRPV4 and TRPC1 proteins were expressed and co-localised at the plasma membrane of freshly isolated endothelial cells (ECs). In wire myography studies, increasing [Ca^2 +]_o between 1 and 6 mM induced concentration-dependent relaxations of methoxamine (MO)-induced pre-contracted tone, which were inhibited by the TRPV4 antagonists RN1734 and HC067047, and the externally-acting TRPC1 blocking antibody T1E3. In addition, CaSR-evoked NO production in ECs measured using the fluorescent NO indicator DAF-FM was reduced by RN1734 and T1E3. In contrast, [Ca^2 +]_o-evoked perforated-patch IK_Ca currents in ECs were unaffected by RN1734 and T1E3. The TRPV4 agonist GSK1016790A (GSK) induced endothelium-dependent relaxation of MO-evoked pre-contracted tone and increased NO production, which were inhibited by the NO synthase inhibitor L-NAME, RN1734 and T1E3. GSK activated 6pS cation channel activity in cell-attached patches from ECs which was blocked by RN1734 and T1E3. These findings indicate that heteromeric TRPV4-TRPC1 channels mediate CaSR-induced vasorelaxation through NO production but not IK_Ca channel activation in rabbit mesenteric arteries. This further implicates CaSR-induced pathways and heteromeric TRPV4-TRPC1 channels in regulating vascular tone.     

Comparative evaluation of different doses of PPAR-γ agonist alone and in combination with sulfasalazine in experimentally induced inflammatory bowel disease in rats

BackgroundInflammatory bowel disease (IBD) is an idiopathic, chronic inflammatory condition, which affects the gastrointestinal tract and has no curative treatment. The present study aimed to investigate the effect of different doses of pioglitazone alone and in combination with sulfasalazine in TNBS (trinitrobenzenesulfonic acid)-induced inflammatory bowel disease (IBD) in rats.MethodsA total of 36 animals were included in the study. Animals were divided into five groups (n = 6): group I – vehicle (ethanol), group II – TNBS + ethanol, group IIIA–TNBS + pioglitazone (15 mg/kg), group IIIB – TNBS + pioglitazone (30 mg/kg), group IV – TNBS + sulfasalazine (360 mg/kg), group V – TNBS + sulfasalazine (360 mg/kg) + pioglitazone (least effective dose found in group III). Group III was divided into two subgroups, namely ULA and IIIB, on the basis of different doses of pioglitazone used. After completion of two weeks of treatment, rats were sacrificed under ether anesthesia by cervical dislocation for assessment of intestinal inflammation, histological analysis, myeloperoxidase assay, malondialdehyde assay and TNF-α estimation.ResultsAll the drug-treated groups showed both gross morphological and microscopic score either 1 or 2. None of them showed score of > 2 on both gross and microscopic morphological examination. Both MDA levels and MPO activity were significantly re-duced in the drug-treated groups, with maximum reduction seen in the combination group. TNF-α was reduced in pioglitazone group. It was highly reduced in sulfasalazine group (group V) as compared to TNBS group thereby indicating that pioglitazone is protective in TNBS-induced inflammatory bowel disease.ConclusionThe present study showed reduction in lipid peroxidation, malondialdehyde levels and TNF-α levels in pioglitazone-treated group and hence, there was significant improvement in gross and microscopic features, too. However, combination of pioglitazone and sulfasalazine has shown greater efficacy.     

NK1 receptor-mediated mechanisms regulate colonic hypersensitivity in the guinea pig

Neurokinin-1 (NK(1)) receptors activated by substance P (SP) are involved in the processing of nociceptive information and are a potential target for therapy of visceral pain. We have evaluated the role of NK(1) receptors using a selective antagonist of NK(1) receptors in two animal models of colorectal hypersensitivity. The behavioral response to colorectal distension was assessed in freely moving guinea pigs by recording visceromotor reflex contractions of the abdominal musculature. Colonic hypersensitivity was induced by intracolonic administration of a chemical irritant (0.6% of acetic acid), or by acute partial restraint stress. Sensitization was characterized by an exaggerated visceromotor response to a low level of colorectal distension (10 mm Hg). In both models of colonic hypersensitivity, oral administration of TAK-637 (0.1-10 mg/kg) normalized visceromotor responses. The intracerebroventricular (10 microg/kg) or intrathecal (10 microg/kg) administration of TAK-637 inhibited colonic hypersensitivity, suggesting an interaction with central NK(1) receptors. In contrast, TAK-637 had no effect on visceromotor responses to colorectal distension at 40 mm Hg in guinea pigs with normosensitive (nonsensitized) colons. In conclusion, central NK(1) receptors play a significant role in colonic hypersensitivity induced by visceral afferent nerve sensitization from gastrointestinal origin or acute psychosomatic stress, but not in the perception of colorectal distension in animals with normosensitive colons.     

Anti-inflammatory action of a novel orally available peptide 317 in mouse models of inflammatory bowel diseases

BackgroundThe endogenous opioid system constitutes an attractive target in the treatment of GI disorders, including inflammatory bowel diseases (IBD). The aim of our study was to characterize the anti-inflammatory and antinociceptive effect of P-317, a novel cyclic analog of opioid peptide morphiceptin, in animal models of IBD.MethodsThe anti-inflammatory effect of P-317 after intraperitoneal (ip) and oral (po) administration was assessed in two mouse models of IBD – Crohn's disease, induced by intracolonic instillation of trinitrobenzenesulfonic acid (TNBS) and ulcerative colitis, induced by addition of dextran sodium sulfate (DSS) into drinking water. The antinociceptive action of P-317 was characterized in mice with acute colitis using mustard oil-induced pain test. Real time RT PCR was used to assess semiquantitatively the expression of IL-1β and TNF-α mRNA in mouse colonic samples. To translate our results to clinical conditions, MOP and KOP mRNA were quantified in human colonic biopsies from IBD patients.ResultsP-317 (0.1 mg/kg, ip and 1 mg/kg, po) alleviated colonic inflammation in TNBS- and DSS-treated mice in the opioid receptor-dependent manner. The anti-inflammatory effect of P-317 was associated with the decrease in mRNA expression of proinflammatory cytokines. The antinociceptive effect of P-317 was observed after ip and po administration in mice with acute colitis.ConclusionOur results show a potent anti-inflammatory and antinociceptive effect of P-317 in mouse models of colitis upon activation of opioid receptors. The unique bioavailability of P-317 after oral administration suggests that it is a promising drug candidate for future treatment of IBD.     

Dextran sulfate sodium-induced acute experimental colitis in C57BL/6 mice is mitigated by selenium

BackgroundSodium selenite has been shown to have a protective role in experimental colitis. Th1 and Th17 responses are involved in the pathogenesis of dextran sulfate sodium (DSS)-induced colitis and inflammatory bowel disease. This study investigated whether sodium selenite can suppress Th1/Th17-mediated experimental colitis.MethodsMice were administered sodium selenite (2 μg/g body weight) by gavage daily for 30 days. Beginning on day 21, mice were administered 2.5% oral DSS for 9 days. The mice were sacrificed on day 31. Survival rates, clinical symptoms, colon lengths, and histological changes were determined.ResultsPretreatment with sodium selenite (2 μg/g body weight) improved survival rates, colon shortening, body weight loss, disease activity index, and histopathological score in mice with DSS-induced colitis. Pretreatment with sodium selenite restored interleukin-10 and Foxp3 excretion, as well as reducing the levels of interferon-γ and interleukin-17A.ConclusionsPretreatment with sodium selenite showed therapeutic potential for preventing colitis in mice. This effect may be mediated by the immunomodulation of regulatory T cells, expressing anti-inflammatory genes that suppress Th1 and Th17 responses.     

N-palmitoyl-vanillamide (palvanil) is a non-pungent analogue of capsaicin with stronger desensitizing capability against the TRPV1 receptor and anti-hyperalgesic activity

N-acyl-vanillamide (NAVAM) analogues of the natural pungent principle of capsicum, capsaicin, were developed several years ago as potential non-pungent analgesic compounds. N-oleoyl-vanillamide (olvanil) and N-arachidonoy-vanillamide (arvanil), in particular, were described in several publications and patents to behave as potent anti-hyperalgesic compounds in experimental models of chronic and inflammatory pain, and to activate both “capsaicin receptors”, i.e. the transient receptor potential of vanilloid type-1 (TRPV1) channel, and, either directly or indirectly, cannabinoid receptors of type-1. Here we report the biochemical and pharmacological characterization of a so far neglected NAVAM, N-palmitoyl-vanillamide (palvanil), and propose its possible use instead of capsaicin, as a possible topical analgesic. Palvanil exhibited a kinetics of activation of human recombinant TRPV1-mediated intracellular calcium elevation significantly slower than that of capsaicin (t_1/2 = 21 s and 8 s, respectively at 1 μM). Slow kinetics of TRPV1 agonists were previously found to be associated with stronger potencies as TRPV1 desensitizing agents, which in turn are usually associated with lower pungency and stronger anti-hyperalgesic activity. Accordingly, palvanil desensitized the human recombinant TRPV1 to the effect of capsaicin (10 nM) with significantly higher potency than capsaicin (IC₅₀ = 0.8 nM and 3.8 nM, respectively), this effect reaching its maximum more rapidly (50 and 250 min, respectively). Palvanil was also more potent than capsaicin at desensitizing the stimulatory effect of TRPV1 by low pH together with anandamide, which mimics conditions occurring during inflammation. In the eye-wiping assay carried out in mice, palvanil was not pungent and instead caused a strong and long-lasting inhibition of capsaicin-induced eye-wiping. Finally, intraplantar palvanil inhibited the second phase of the nociceptive response to formalin in mice. In conclusion, palvanil appears to be a non-pungent analogue of capsaicin with stronger desensitizing effects on TRPV1 and hence potentially higher anti-hyperalgesic activity.     

Protective effect of gentiopicroside against dextran sodium sulfate induced colitis in mice

This study was designed to investigate the anti-inflammatory activity of the pure compound gentiopicroside (Gent) on dextran sulfate sodium (DSS)-induced colitis in a mouse model and to explore the possible related mechanisms. Experimental colitis was induced in ICR mice by dissolving 5% DSS in their drinking water for 7 days. Gent (200, 100, and 50 mg/kg) and 5-aminosalicylic acid (5-ASA, 100 mg/kg) were oral administrated once a day for 7 days. Anti-inflammatory effects were evaluated by comparing extend of colonic mucosal injury assessed by disease activity index (DAI), colon length, histopathological examination, and biochemical test. The possible mechanisms of Gent activities were explored by evaluating expression levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 using real-time fluorogenic PCR and expression levels of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) using Western blotting. The results showed that oral administration of Gent significantly attenuated DSS-induced loss of body weight, diarrhea, shortening of colon length and histological changes, associated with the decrease in the activity of myeloperoxidase (MPO) in the colon. In addition, the mRNA expression of TNF-α, IL-1β, IL-6 and the overexpression of COX-2 and iNOS proteins in the colon were down-regulated by Gent treatment. To our knowledge, this is the first study to demonstrate that Gent treatment can exert anti-inflammatory effects on experimental acute colitis through attenuating the expression levels of TNF-α, IL-1β, IL-6, iNOS and COX-2, and it may present the therapeutic potential in the treatment of colitis.     

Treatment with recombinant tissue plasminogen activator (r-TPA) induces neutrophil degranulation in vitro via defined pathways

Thrombolysis is recommended for reperfusion following acute ischemic stroke (AIS), but its effects on stroke-associated injury remain to be clarified. Here, we investigated the effects of recombinant tissue plasminogen activator (r-tPA) on neutrophil pathophysiology in vitro and in a case–control study with AIS patients submitted (n = 60) or not (n = 30) to thrombolysis. Patients underwent radiological and clinical examination as well as blood sampling at admission and after 1, 7 and 90 days. In vitro, 30-min incubation with 0.1–1 mg/ml r-tPA induced neutrophil degranulation in different substrate cultures. Pre-incubation with kinase inhibitors and Western blot documented that degranulation was associated with activation of PI3K/Akt and ERK1/2 pathways in Teflon dishes and PI3K/Akt in polystyrene. In thrombolysed patients, a peak of neutrophil degranulation products (matrix metalloproteinase [MMP]-9, MMP-8, neutrophil elastase and myeloperoxidase), was shown during the first hours from drug administration. This was accompanied by serum augmentation of protective tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. An increased rate of haemorrhagic transformations on day 1 after AIS was shown in thrombolysed patients as compared to non-thrombolysed controls. In conclusion, r-tPA treatment was associated with in vitro neutrophil degranulation, indicating these cells as potential determinants in early haemorrhagic complications after thrombolysis in AIS patients.     

Establishment and validation of a new semi-chronic dextran sulfate sodium-induced model of colitis in mice

BackgroundThe dextran sulfate sodium (DSS)-induced model of colitis is a commonly used model of inflammatory bowel disease (IBD) in animals. However, there were few studies on the therapeutic efficacy of drugs for IBD after the onset of colitis in this model. We established a semi-chronic model of DSS-induced colitis in mice and used it to assess the therapeutic efficacy of agents for IBD.Materials and methodsColitis was induced by administration of 3% DSS in drinking water to mice for 7 days followed by 5 days of normal drinking water.ResultsUlcerative colitis (UC)-like symptoms including diarrhea, bloody stools and body-weight loss were observed from days 3 to 5, and continued until day 12 after DSS administration. Persistent colitis was associated with sustained local production of cytokines and was characterized by infiltration of inflammatory cells, crypt loss and erosion in the distal colon. These features are similar to those found in patients with UC. In this model, anti-tumor necrosis factor (TNF)-α antibody or anti-interleukin (IL)-12/23p40 antibody significantly ameliorated colitis when administered after the onset of colitis. However, treatment with FK506, prednisolone or sulfasalazine provided limited therapeutic benefit.ConclusionThe DSS-induced colitis established here showed similar symptomatic and histopathological features to those seen in human UC. This model may be available for predicting the clinical efficacy of candidate compounds for UC.