Ocular inflammation models by topical application: croton-oil induced uveitis

New insights into the emerging effects of inflammatory response on HDL particles structure and function

According to the increasing results, it has been well-demonstrated that the chronic inflammatory response, including systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease are associated with an increased risk of atherosclerotic cardiovascular disease. The mechanism whereby inflammatory response up-regulates the risk of cardio-metabolic disorder disease is multifactorial; furthermore, the alterations in high density lipoprotein (HDL) structure and function which occur under the inflammatory response could play an important modulatory function. On the other hand, the serum concentrations of HDL cholesterol (HDL-C) have been shown to be reduced significantly under inflammatory status with remarked alterations in HDL particles. Nevertheless, the potential mechanism whereby the inflammatory response reduces serum HDL-C levels is not simply defined but reduces apolipoprotein A1 production. The alterations in HDL structure mediated by the inflammatory response has been also confirmed to decrease the ability of HDL particle to play an important role in reverse cholesterol transport and protect the LDL particles from oxidation. Recently, it has been shown that under the inflammatory condition, diverse alterations in HDL structure could be observed which lead to changes in HDL function. In the current review, the emerging effects of inflammatory response on HDL particles structure and function are well-summarized to elucidate the potential mechanism whereby different inflammatory status modulates the pathogenic development of dyslipidemia.

The influence of compatibility of traditional Chinese medicine on the pharmacokinetic of main components in Fructus aurantii

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Aurantii is one of the commonly used traditional Chinese medicines and the compatibility of Fructus Aurantii, Radix et Rhizoma Rhei and Semen Crotonis Pulveratum were the main components in a Chinese traditional patent medicine Weichang'an pill. Naringin and neohesperidin are two main flavonoid glycosides in the extract of Fructus Aurantii. The pharmacokinetics of naringin and neohesperidin, as the main marker constituents were analysis by a simple and accurate method.

MATERIALS AND METHODS

In the present study, pharmacokinetic differences of two flavonoid glycosides were detected after oral administration of the extract of single herb and different compatibility of Fructus Aurantii, Radix et Rhizoma Rhei and Semen Crotonis Pulveratum which at doses of approximately 700 mg/kg naringin and 300 mg/kg neohesperidin.

RESULTS

It indicated that the pharmacokinetic process of naringin and neohesperidin in four groups were demonstrated bimodal phenomenon after oral administration. Comparing to pharmacokinetic parameters of the single herbs administration, there were no significant difference after the compatibility of Fructus Aurantii and Radix et Rhizoma Rhei. However, the absorption of two flavonoid glycosides was increased dramatically after the compatibility of Fructus Aurantii or Semen Crotonis Pulveratum. The same results were attained after co-administration of the extract of three herbs.

CONCLUSION

Some components in the extract of Semen Crotonis Pulveratum promoted the absorption of naringin and neohesperidin.

Activation of M3 muscarinic receptor and Ca²⁺ influx by crude fraction from Crotonis Fructus in isolated rabbit jejunum

ETHNOPHARMACOLOGICAL RELEVANCE

Crotonis Fructus is the mature fruit of Croton tiglium L. (Euphorbiaceae), which has been used in traditional Chinese medicine for the treatment of gastrointestinal (GI) diseases, such as constipation, abdominal pain, peptic ulcer, and intestinal inflammation for thousands of years. The aim of this study was to investigate the pharmacological effect of extracts and fractions from Crotonis Fructus on GI tract.

MATERIALS AND METHODS

The activities of methanol extract and fractions from Crotonis Fructus on the smooth muscle contractions were evaluated using isolated rabbit jejunum model.

RESULTS

The results suggest that the n-BuOH and H(2)O fractions showed spasmolytic activity, while the MeOH extract, PE and EtOAc fractions exerted spasmogenic effect. Moreover, bioassay-guided fractionation verified that the EtOAc fraction was more potent than others, followed by PE fraction and methanol extract. Additionally, atropine (10μM), 4-DAMP (10μM) and verapamil (0.1μM) produced a significant inhibition of contractions caused by EtOAc fraction, while either hexamethonium (10μM) or methoctramine (10μM) was inactive. Additionally, a HPLC fingerprint of EtOAc fraction was appraised to ensure its chemical consistency and the main component has been identified as phorbol 12-acetate-13-tiglate.

CONCLUSIONS

These data indicate that the regulatory effect of EtOAc fraction on GI motility are medicated via the activation of M3 muscarinic receptor and Ca(2+) influx through L-type Ca(2+) channel. These provide a scientific basis for the traditional use of Crotonis Fructus in GI disorders.

M3 muscarinic receptor- and Ca2+ influx-mediated muscle contractions induced by croton oil in isolated rabbit jejunum

AIM OF STUDY

Croton oil is the fruit oil of Croton tiglium L., which is well known in folk medicine for the treatment of gastrointestinal (GI) diseases, including constipation, abdominal pain, peptic ulcer, and intestinal inflammation for a long period. This study was to investigate the pharmacological effect of croton oil on GI tract.

MATERIALS AND METHODS

The effect of croton oil on the smooth muscle contractions was investigated in vitro using the isolated rabbit jejunum model.

RESULTS

Croton oil has a biphasic action contracting and relaxing intestinal tissue. At the concentrations of 20-80 microg/mL, croton oil produced a concentration-dependent increase in the amplitude and tension of muscle contractions, whereas at high concentrations (>200 microg/mL) it decreased the contractile amplitude and had no impact on the tension. Moreover, croton oil was less effective in increasing muscle amplitude and tension than Ach, confirming that the effect of croton oil on muscle contractions is not a simply stimulatory or inhibitory action, but a unique modulatory process depending on the concentration of croton oil. In addition, croton oil concentration-dependently suppressed the frequency of muscle contractions. On the other hand, atropine (10 microM) and 4-DAMP (10 microM) produced a significant inhibition of contractions caused by croton oil, while either hexamethonium (10 microM) or methoctramine (10 microM) was inactive, implying that the regulatory effects of croton oil on GI motility are mediated via the activation of M3 muscarinic receptor. Furthermore, muscle contractions induced by croton oil were dramatically reduced by verapamil (0.1 microM) but not by NE (1 microM), suggesting that the action of croton oil on GI motility is also mediated by Ca(2+) influx through L-type Ca(2+) channel.

CONCLUSIONS

The results suggest that croton oil possesses spasmogenic and spasmolytic properties and the regulatory effects of croton oil on GI motility are mediated via the activation of M3 muscarinic receptor and Ca(2+) influx through L-type Ca(2+) channel.

Biodegradable scleral implants as new triamcinolone acetonide delivery systems

The goal of this study was to develop ocular scleral implants able to release triamcinolone acetonide (TA) overall several months. Scleral discs were manufactured by a compression-molding method using a new synthetic polymer, poly(methylidene malonate) (PMM2.1.2), as matrix. Implants with good mechanical properties adapted for in vivo implantation have been obtained when using high M(w) PMM2.1.2 (100,000 - 150,000 Da) associated with ethoxylated derivatives of stearic acid (Simulsol) or oligomers of methylidene malonate as plasticizer. After implantation in rabbit eyes, scleral implants showed a good ocular biocompatibility. Indeed, the clinical follow-up and ocular inflammation parameters, such as inflammatory cell number and protein content in aqueous humor, demonstrated that implants were well tolerated and did not provoke abnormal inflammation. Implants were able to release significant concentrations of TA in the vitreous and the sclera throughout 5 weeks.

Direct effect of croton oil on intestinal epithelial cells and colonic smooth muscle cells

AIM

To investigate the direct effect of croton oil (CO) on human intestinal epithelial cell (HIEC) and guinea pig colonic smooth muscle cells in vitro.

METHODS

Growth curves of HIEC were drawn by MTT colorimetry. The dynamics of cell proliferation was analyzed with flow cytometry, and morphological changes were observed under light and electron microscopy after long-term (6 weeks) treatment with CO. Expression of cyclooxygenase-2 (COX-2) mRNA was detected by dot blot in HIEC treated with CO. Genes related to CO were screened by DD-PCR, and the direct effect of CO on the contractility of isolated guinea pig colonic smooth muscle cells was observed.

RESULTS

High concentration (20-40 mg x L(-1)) CO inhibited cell growth significantly (1, 3, 5, 7d OD sequence: (20 mg x L(-1)) 0.040+/-0.003, 0.081+/-0.012, 0.147+/-0.022,0.024+/-0.016; (40 mg x L(-1)) 0.033+/-0.044, 0.056+/-0.012, 0.104+/-0.010, 0.189+/-0.006; OD control 0.031+/-0.008, 0.096+/-0.012, 0.173+/-0.009, 0.300+/-0.016, P<0.01), which appeared to be related directly to the dosage. Compared with the control, the fraction number of cells in G1 phase decreased from 0.60 to 0.58, while that in S phase increased from 0.30 to 0.34 and DNA index also increased after 6 weeks of treatment with CO (the dosage was increased gradually from 4 to 40 mg x L(-1)). Light microscopic observation revealed that cells had karyomegaly, less plasma and karyoplasm lopsidedness. Electron microscopy also showed an increase in cell proliferation and in the quantity of abnormal nuclei with pathologic mitosis. Expression of COX-2 mRNA decreased significantly in HIEC treated with CO. Thirteen differential cDNA fragments were cloned from HIEC treated with CO, one of which was 100 percent homologous with human mitochondrial cytochrome C oxidase subunit II. The length of isolated guinea pig colonic smooth muscle cells was significantly shortened after treatment with CO (P<0.05).

CONCLUSION

At a high CO concentration (>20 mg x L(-1)), cell growth and proliferation are inhibited in a dosage-dependent manner. Increase in cell proliferation and in malignant conversion of the cellular phenotype is observed in cells cultured chronically with CO. COX-2 mRNA expression decreases significantly, while human mitochondrial cytochrome C oxidase subunit IImRNA expression increases significantly in HIEC treated with CO. CO also has a direct effect on the contractility of Guinea pig colonic smooth muscle cells.

Antisense oligodeoxynucleotides to mu- and delta-opioid receptor mRNA block the enhanced effects of opioids during intestinal inflammation

Intestinal inflammation enhances the inhibitory effects of mu- and delta-opioids in the gut, possibly related to an increased receptor expression. We evaluated the effects of opioids after intraperitoneal administration of antisense oligodeoxynucleotides to mu- and/or delta-opioid receptor mRNA. Inflammation was induced in mice by intragastric administration of croton oil; gastrointestinal transit was assessed with charcoal and permeability with [51Cr]etylenediaminetetraacetate ([51Cr]EDTA). Baseline values were unaltered after antisense oligodeoxynucleotides. In controls, antisense oligodeoxynucleotides to mu-opioid receptor mRNA decreased the antitransit effects of morphine (27%) and [N-MePhe3D-Pro4]morphiceptin (PL017) (26%), and the reduction was significantly greater during inflammation (50% and 47%). A similar effect was observed on permeability (control: 41-21% decrease; inflamed: 66-45%). In both assays, antisense oligodeoxynucleotides to delta-opioid receptor mRNA also reduced the effects of [D-Pen2,5]enkephalin (DPDPE) in a higher percentage during inflammation (43-32% controls, 60-49% inflamed). We show that antisense oligodeoxynucleotides to mu- and/or delta-opioid receptor mRNA are efficiently blocking the intestinal effects of opioids during inflammation, suggesting that an increased transcription of these receptors in the gut mediates the enhanced effects of opioids during inflammation.

Suppression of croton oil-induced rabbit corneal edema by sideritis javalambrensis

This investigation was designed to evaluate the anti-inflammatory activity of the aqueous and hexane extracts of Sideritis javalambrensis, to which pharmacological properties have been attributed in Spanish traditional medicine. The extracts were applied as eye drops in a croton oil-induced corneal edema model in rabbits. Corneal thickness was estimated before the induction of inflammation and 3, 6, 8, 12, 48, 72 and 96 h after induction. Significant inflammation inhibition percentages were shown during both the acute and chronic stages of inflammation by both extracts and by the reference drug dexamethasone, with most therapeutic effect shown during the chronic phase. However, the hexane extract exhibited potent anti-inflammatory activity from 6 to 24 h post-induction, achieving greater percentage inhibition values during this stage than those obtained for dexamethasone.

Chronic hypersensitivity for inflammatory nociceptor sensitization mediated by the epsilon isozyme of protein kinase C

We have identified a mechanism, mediated by the epsilon isozyme of protein kinase C (PKCepsilon) in peripheral neurons, which may have a role in chronic inflammatory pain. Acute inflammation, produced by carrageenan injection in the rat hindpaw, produced mechanical hyperalgesia that resolved by 72 hr. However, for up to 3 weeks after carrageenan, injection of the inflammatory mediators prostaglandin E(2) or 5-hydroxytryptamine or of an adenosine A(2) agonist into the same site induced a markedly prolonged hyperalgesia (>24 hr compared with 5 hr or less in control rats not pretreated with carrageenan). A nonselective inhibitor of several PKC isozymes and a selective PKCepsilon inhibitor antagonized this prolonged hyperalgesic response equally. Acute carrageenan hyperalgesia could be inhibited by PKA or PKG antagonists. However, these antagonists did not inhibit development of the hypersensitivity to inflammatory mediators. Our findings indicate that different second messenger pathways underlie acute and prolonged inflammatory pain.