Guinea Pig Ileum Preparations Research Articles

EVALUATION OF ANTI-ASTHMATIC ACTIVITY OF ETHANOLIC EXTRACT OF CYNODON DACTYLON LEAVES

In the present study Cynodon dactylon leaves ethanolic extract and its chloroform and ethyl acetate fractions were used to evaluate the anti-asthmatic activity, using various experimental in vivo and in vitro animal models. Ethanolic extract of Cynodon dactylon and its chloroform and ethyl acetate fractions were evaluated for its anti-asthmatic activity by in vitro models (isolated guinea pig ileum preparation and isolated guinea pig tracheal chain preparation) in vivo models (Histamine and acetylcholine induced bronchospasm in guinea pigs and milk induced eosinophilia in mice model). Ethanolic extract of Cynodon dactylon and its ethyl acetate fraction at the concentration of 10 mg significantly antagonized the effect of histamine induced contraction on isolated guinea pig ileum preparation. Ethyl acetate fraction of Cynodon dactylon showed the maximum spasmolytic activity and significantly extended the latent period of convulsion as compared to standard (Ketotifen fumarate) upon histamine and acetylcholine exposure in a dose dependent manner. The study concluded that, chloroform and ethyl acetate fractions of Cynadon dactylon was shown significant anti-asthmatic activity.

Fadolmidine – Favourable adverse effects profile for spinal analgesia suggested by in vitro and in vivo models

Fadolmidine is an α2-adrenoceptor full agonist developed for spinal analgesia with a local mode of action. The purpose of this study was to demonstrate the safety of fadolmidine on known α2-adrenoceptor-related effects: kidney function, urodynamics and cardiovascular variables. Furthermore, the binding affinity of fadolmidine for the 5-HT3 receptor prompted functional studies on 5-HT3. According to the binding affinity data, fadolmidine demonstrated partial agonism on the 5-HT3 receptor in transfected cells and in guinea pig ileum preparation. However, intravenous (IV) fadolmidine did not produce any 5-HT3-related hemodynamic effects in anaesthetised rats. In urodynamic studies, intrathecal (IT) fadolmidine interrupted volume-evoked voiding cycles and induced overflow incontinence at high concentrations in anaesthetised rats; however, at the analgesic dose range, the effects were mild. The effects of fadolmidine on kidney function were studied in conscious rats after IV and IT dosing. While IT fadolmidine increased dose-dependent urine output, sodium ion concentration, IV doses increased only sodium ion concentration The effects of IT fadolmidine on heart rate (HR), mean arterial pressure (MAP) and sedation were evaluated in the home cage and in the open field using a telemetry system. In resting conditions, fadolmidine decreased HR dose-dependently and increased initial MAP, whereas in actively moving rats, there were no effects at analgesic doses. The results suggest that at anticipated analgesic clinical doses, IT fadolmidine provides analgesia without significant adverse effects on sedation, MAP or HR and with only modest effects on kidney function and urodynamics.

Bergapten modulates ovalbumin-induced asthma

Prior studies on the anti-inflammatory compound bergapten have shown promise in averting allergic airway hyperresponsiveness. This study sought to establish its possible role in modulating an immunologically-induced airway inflammation and hyperresponsiveness in an ovalbumin model of asthma. Asthma is characterised by inflammation and constriction of the airway passages. Therapy is aimed at bronchodilation and reducing inflammation. Histamine is an inflammatory mediator and involved in immune reactions. It is released from mast cells which are important sentinel cells of the innate immune system involved in the inflammatory response. In the asthma model, ovalbumin solution (2 mg ovalbumin) was administered i.p. as a sensitisation dose on day 1 and on day 14 as a booster dose to sensitise the immune system. This was followed by a 10-day challenge on days 21 – 30 using aerosolised ovalbumin (1% w/v dissolved in phosphate-buffered saline, PBS) at a cut-off latency of 10 min. Bergapten was administered at doses of 3 - 30 mg kg−1 p.o. 1 h prior to each challenge. Times to pre-convulsive dyspnoea were recorded. Guinea-pigs were sacrificed and lungs harvested for histological and antioxidant studies. In determining the effect of bergapten on histamine, an isolated guinea pig ileum preparation by the administration of bergapten (1 – 10 µg ml−1) in the presence of histamine. Bergapten increased times to pre-convulsive dyspnoea in the ovalbumin challenge and reduced pathological damage to bronchial tissue. The deposition of collagen around bronchioles was minimised. Antioxidant studies showed higher catalase and superoxide dismutase activity in groups treated with bergapten. Bergapten produced a rightward shift on the Schild plot analysis with a slope of 1.4 and a pA2 value of 9.3 was obtained in the isolated tissue experiment which confirms that bergapten acts as an antagonist on histaminic H1 receptors. Bergapten modulates inflammation in ovalbumin-induced asthma and antagonises histamine at the H1 receptor.

Anti-allergy and anti-tussive activity of Clitoria ternatea L. in experimental animals

Ethnopharmacological relevanceClitoria ternatea flower is traditionally used in the treatment of respiratory disorders including bronchitis and is one of the ingredients in different Ayurvedic preparations that are used in respiratory disorders. However, till date there is no scientific report on the anti-asthmatic activity of this flower. Aim of the studyEthanolic extract of Clitoria ternatea flowers (ECT) was evaluated for its anti-allergy and anti-tussive potential in experimental animals. Additionally, the anti-inflammatory potential of ECT was carried out to draw a plausible mechanism of action of the drug. Materials and MethodsIn-vitro anti-asthmatic activity of ECT was evaluated in goat tracheal chain and isolated guinea pig ileum preparations. Acute and chronic anti-asthmatic activity of ECT (100, 200 and 400 mg/kg; p.o.) was estimated in histamine aerosol exposed guinea pigs and in OVA sensitized and challenged mice respectively. Anti-tussive activity of ECT (100, 200 and 400 mg/kg; p.o.) was evaluated against sulfur dioxide- and citric acid-induced cough in experimental animals. Moreover, the anti-inflammatory activity of ECT (100, 200 and 400 mg/kg; p.o.) was evaluated against carrageenan- and acetic acid-induced inflammation in rats. ResultsECT attenuated histamine-induced contraction in both goat tracheal chain and isolated guinea pig ileum preparations. ECT (400 mg/kg) attenuated histamine-induced dyspnoea and OVA-induced changes in differential cell count in broncheoalveolar fluid, levels of interleukins (IL-1beta and IL-6) and immunoglobulin (OVA-sensitive IgG1) in animals. ECT (400 mg/kg) further ameliorated sulfur dioxide- and citric acid-induced cough in experimental animals. Additionally, ECT (400 mg/kg) attenuated inflammation in carrageenan and acetic acid challenged rodents. ConclusionsStandardized ECT could be considered as a potential therapeutic alternative in the management of allergy-induced asthma.

Pharmacological Evaluation of Gut Modulatory and Bronchodilator Activities of Achyranthes aspera Linn.

Achyranthes aspera L. is traditionally used to relieve constipation, diarrhea, and asthma. Its crude extract (Aa.Cr) was evaluated through in vivo and ex vivo experiments to rationalize these medicinal uses of A. aspera and to provide their scientific basis. Aa.Cr, at 3 and 10mg/kg, increased fecal output, similar to castor oil, whereas at 30, 100, 300, and 700mg/kg, it protected against castor oil-induced diarrhea in mice when administered orally. Aa.Cr caused spasmogenic effect on rabbit jejunum and guinea pig ileum preparations, which was partially inhibited by atropine while completely blocked by cyproheptadine preincubation. Aa.Cr also relaxed high K+ (80mM)-induced contraction in rabbit jejunum. Aa.Cr inhibited CCh (100μg/kg)-induced bronchospasm in rats, similar to aminophylline. Like dicyclomine, Aa.Cr relaxed high K+ and CCh (1μM)-induced contractions in guinea pig trachea and caused rightwards parallel shift of CCh concentration-response curves at the lower concentrations followed by non-parallel shift at the higher concentrations. On activity-directed fractionation, spasmogenic and spasmolytic activities of Aa.Cr were concentrated in aqueous and organic fraction, respectively. This study suggests the presence of dose-specific laxative and antidiarrheal effects in A. aspera, possibly mediated through cyproheptadine-sensitive receptors and dual cholinergic and calcium channel blockade, respectively. The latter combination is also a suggested mechanism underlying its bronchodilator effect. Copyright © 2017 John Wiley & Sons, Ltd.

Evaluation of anti-histaminic and bronchodilatory Activity of milk of equus africanus Asinus in rodents

The Equus africanus asinus milk commonly known as donkey milk (DM) is often used as a substitute for breast milk, and as medicine for treating the child of delicate health, improving immunity, treatment of respiratory problems like cough, whooping cough and asthma in infants.The present study was therefore designed to evaluate the antihistaminic and bronchodilator activity of milk of Equus africanus asinus in rodents. Equus asinus milk was evaluated using histamine induced contractions on isolated ileum and tracheal chain preparations and histamine induced bronchoconstriction in Guinea pigs. The Equus asinus milk significantly inhibited histamine induced contraction of isolated guinea pig ileum and tracheal chain preparation and significantly protected the guinea pigs against histamine induced Bronchoconstriction as indicated by delay in the pre-convulsive dyspnoea time (PCT) following the exposure of histamine aerosol. The results suggested that Equus asinus milk has antihistaminic and bronchodilator activity and may prove beneficial effect in the management of asthma.

Dual effectiveness of Flaxseed in constipation and diarrhea: Possible mechanism

Ethnopharmacological relevanceThis study was planned to assess pharmacological basis for the medicinal use of Flaxseed in constipation and diarrhea. Materials and methodsThe oil and mucilage of Flaxseeds were studied for their laxative, and antidiarrheal activities in mice. The mechanisms of laxative and antidiarrheal activities were further studied using the isolated tissue preparations (rabbit jejunum and guinea-pig ileum) immersed in Tyrode׳s solution maintained at 37°C and aerated with carbogen gas. Isotonic responses were measured on spontaneously contracting isolated jejunum and guinea-pig ileum preparations. ResultsOral administration of Flaxseed oil (30 and 70mg/kg, orally) and mucilage (1 and 2.5g/kg, orally) caused dose-dependent increase in wet feces in mice. The spasmogenic effect of Flaxseed oil was partially blocked by pyrilamine (p<0.05) and atropine (p<0.01) in isolated rabbit jejunum whereas atropine completely blocked the effect of Flaxseed mucilage on isolated guinea-pig ileum. When studied for its antidiarrheal effect, Flaxseed oil reduced the castor oil-induced diarrheal score by 49.35% and 84.41% and intestinal secretions by 19% and 33.62% at the oral doses of 100 and 300mg/kg respectively. In isolated rabbit jejunum preparations, Flaxseed oil produced a dose-dependent inhibition of both spontaneous and low K+ (25mM) -induced contractions in rabbit jejunum. The inhibitory effect against low K+ was most sensitive to tetra-ethylammonium chloride, a non-specific K+ channel blocker, followed by glibenclamide, a partial ATP-dependent K+ channels blocker and 4-Aminopyridine, a voltage gated K+-channel blocker. ConclusionsOur results indicate that Flaxseed oil and mucilage exhibit laxative activity, mediated primarily through cholinergic pathway with weak histaminergic effect component evident in Flaxseed oil, which also showed antidiarrheal activity, mediated possibly through K+ channels activation. Thus this study rationalizes the medicinal use of Flaxseed in both the constipation and diarrhea with sound mechanistic basis.

A1-adenosine acute withdrawal response and cholecystokinin-8 induced contractures are regulated by Ca2+- and ATP-activated K+ channels

In isolated guinea-pig ileum (GPI), the A1-adenosine acute withdrawal response is under the control of several neuronal signalling systems, including the μ/κ-opioid and the cannabinoid CB1 systems. It is now well established that after the stimulation of the A1-adenosine system, the indirect activation of both μ/κ-opioid and CB1 systems is prevented by the peptide cholecystokinin-8 (CCk-8). In the present study, we have investigated the involvement of the Ca2+/ATP-activated K+ channels in the regulation of both acute A1-withdrawal and CCk-8-induced contractures in the GPI preparation. Interestingly, we found that: (a) the A1-withdrawal contracture is inhibited by voltage dependent Ca2+-activated K+ channels, Kv, while it is enhanced by the voltage independent Ca2+-activated K+ channels, SKCa; (b) in the presence of CCk-8, the inhibitory effect of the A1 agonist, CPA, on the peptide induced contracture is significantly enhanced by the voltage independent Ca2+-activated K+ channel, SKCa; and (c) the A1-withdrawal contracture precipitated in the presence of CCk-8 is controlled by the ATP-sensitive potassium channels, KATP. Our data suggest, for the first time, that both Ca2+- and ATP-activated K+ channels are involved in the regulation of both A1-withdrawal precipitated and CCk-8 induced contractures.

Pharmacological basis for the medicinal use of Carissa carandas in constipation and diarrhea

Ethnopharmacological relevanceCarissa carandas Linn. commonly known as “Karaunda” (Apocynaceae) is a popular medicinal herb widely distributed in different parts of Pakistan. In addition to other medicinal uses, Carissa carandas is popular in indigenous system of medicine for its medicinal use in gut motility disorders like, constipation and diarrhea. ObjectiveThis study was planned to provide pharmacological basis to the medicinal use of Carissa carandas in constipation and diarrhea. Materials and methodsThe crude extract of the leaves of Carissa carandas (Cc.Cr) was prepared in methanol and its fractionation was carried out with ethylacetate, petroleum ether and n-butanol. In-vivo studies were conducted on mice, while isolated rabbit jejunum and guinea-pig ileum preparations were used for the in-vitro experiments. The spasmogenic and spasmolytic responses of gut tissues were recorded using isotonic transducers coupled with PowerLab data acquisition system. ResultsThe HPLC fingerprints of Cc.Cr, its petroleum (Cc.Pef), ethylacetate (Cc.Eaf) and n-butanol (Cc.Baf) fractions showed the presence of oleanolic acid, ursolic acid, stigmasterol and β-sitosterol. Oral administration of Cc.Cr to mice increased fecal output at lower doses (30 and 50mg/kg), while it showed protection against castor oil-induced diarrhea at higher doses (300 and 600mg/kg). In isolated guinea-pig ileum and rabbit jejunum, Cc.Cr and Cc.Baf exhibited stimulatory effect at 0.003–3mg/ml, which was partially sensitive to atropine or pyrillamine or partially/fully sensitive to atropine+pyrillamine, followed by relaxation at higher tested concentrations, being more potent in rabbit tissues. The ethylacetate fraction (0.1–5mg/ml) exhibited fully atropine-sensitive contractions in both guinea-pig and rabbit tissues, being more potent in guinea-pig while more efficacious in rabbit tissues. However, the petroleum fraction (0.003–1.0mg/ml) showed only spasmolytic activity in spontaneously contracting rabbit tissues, similar to nifedipine. In guinea-tissue, Cc.Pef did not cause any stimulant effect. When studied against high K+ (80mM)-induced contraction, the crude extract and its fractions caused a dose-dependent inhibition, with the following order of potency: Cc.Pef>Cc.Eaf>Cc.Cr≥Cc.Baf, similar to nifedipine indicating Ca++ channel antagonist like activity, which was further confirmed when the plant extract displaced Ca++ curves to the right with suppression of maximum effect similar to that of nifedipine. ConclusionThis study demonstrates that the crude extract of Carissa carandas possesses a gut-stimulatory effect mediated primarily through the activation of muscarinic and histaminergic receptors while its spasmolytic effect was mediated possibly through Ca++ antagonist pathway. Thus, this study provides a clear evidence for the dual effectiveness of Carissa carandas in constipation and diarrhea, thus validating its medicinal use.

Investigation into the mechanism of action of essential oil of Pistacia integerrima for its antiasthmatic activity

Ethnopharmacological relevancePistacia integerrima J.L. Stewart ex Brandis locally known as Karkatashringi is an important medicinal plant whose galls are valued in traditional medicine used in India for the treatment of asthma, chronic bronchitis, phthisis, diarrhea, fever, other ailments for the respiratory tract, and as antispasmodic, carminative, antiamoebic and anthelmintic. However, in vitro and in vivo investigations providing new insights into its pharmacological properties have not been thoroughly investigated yet. The present investigation aimed to elucidate the probable mechanism of antiasthmatic action of essential oil of Pistacia integerrima J.L. Stewart ex Brandis galls (EOPI). MethodsEOPI was tested using in vitro studies such as antioxidant activity, mast cell degranulation, angiogenesis, isolated guinea pig ileum preparation and soyabean lipoxidase enzyme activity. In vivo studies included lipopolysaccharide-induced bronchial inflammation in rats and airway hyperresponsiveness in ovalbumin in sensitized guinea pigs using spirometry. ResultsEOPI (5–30µg/ml) inhibits 5-lipoxidase enzyme activity with IC50 of 19.71µg/ml and DPPH scavenging activity up to 100µg/ml with maximum inhibition of 44.93±2.53% at 100µg/ml. Pre-treatment with EOPI inhibited erythropoietin-induced angiogenesis. It showed dose dependent (10, 30 and 100µg/ml) anti-allergic activity by inhibiting compound 48/80 induced mast cell degranulation to an extent 19.08±0.47%. The finding that essential oil induced inhibition of transient contraction of acetylcholine in calcium free medium, and relaxation of S-(-)-Bay 8644-precontracted isolated guinea pig ileum jointly suggests that the L-subtype Cav channel is involved in spasmolytic action of EOPI.Treatment with EOPI dose dependently (7.5, 15 and 30mg/kg i.p.) inhibited lipopolysaccharide-induced increase in total cell count, neutrophil count, nitrate–nitrite, total protein, albumin levels in bronchoalveolar fluid and myeloperoxidase levels in lung homogenates. Roflumilast was used as a standard. EOPI reduced the respiratory flow due to gasping in ovalbumin sensitized guinea pigs. ConclusionThe study demonstrates the effectiveness of essential oil of Pistacia integerrima J.L. Stewart ex Brandis galls in bronchial asthma possibly related to its ability to inhibit L-subtype Cav channel, mast cell stabilization, antioxidant, angiostatic and through inhibition of 5-lipoxygenase enzyme.

Preliminary pharmacological investigation of the ischuretic property and safety of a hydro-ethanolic extract of Amaranthus spinosis (Fam: Amaranthaceae)

Background: Ischuria is a health and social problem, having a negative impact on sufferers. This study therefore was a preliminary investigation of the ischuretic property and safety for use of a hydro-ethanolic extract of Amaranthus spinosus used traditionally in managing ischuria. Methods: Phytochemical screening, thin layer chromatography and high performance liquid chromatography were performed on the extract to establish fingerprints for identification. Acetylcholine, Nicotine, and the extract were applied to an isolated rat urinary bladder to ascertain contractile response. The possible receptor site(s) of action was also investigated using isolated rabbit jejunum, and guinea-pig ileum preparations. In-house observation, hematological analysis, and liver and kidney function tests were performed on Sprague-Dawley rats, in acute and sub-acute toxicity studies. Results: The extract had contractile effects on the rat urinary bladder (similar to acetylcholine and nicotine) and rabbit jejunum. Its contractile effect of the guinea-pig ileum was significantly inhibited by hexamethonium (77.50 ± 8.50 %; P ≤ 0.001) and to a lesser extent by mepyramine (49.2 ± 6.80 %; P ≤ 0.001) and Atropine (22.45 ± 5.22 %; P ≤ 0.01). The extract (80-800 mg kg -1 ) was not lethal and a 160 and 240 mg kg -1 dose had no adverse effect on blood, liver, kidney metabolic function. Conclusions: The hydro-ethanolic extract of Amaranthus spinosus has ischuretic activity possibly mediated via nicotinic, histaminic and muscarinic receptor stimulation and is safety to use in ischuria.

Effect of thienorphine on intestinal transit and isolated guinea-pig ileum contraction

To evaluate the effect of thienorphine on small intestinal transit in vivo and on guinea-pig ileum (GPI) contraction in vitro. The effects of thienorphine on intestinal transit were examined in mice and in isolated GPI. Buprenorphine and morphine served as controls. The distance traveled by the head of the charchol and the total length of the intestine were measured in vivo. Gastrointestinal transit was expressed as a percentage of the distance traveled by the head of the marker relative to the total length of the small intestine. The isolated GPI preparations were connected to an isotonic force transducer and equilibrated for at least 1 h before exposure to drugs. Acetylcholine was used for muscle stimulation. Thienorphine (0.005-1.0 mg/kg, ig) or buprenorphine (0.005-1.0 mg/kg, sc) dose-dependently significantly inhibited gut transit compared with saline. Thienorphine inhibited gut transit less than buprenorphine. The maximum inhibition by thienorphine on the intestinal transit was 50%-60%, whereas the maximum inhibition by morphine on gut transit was about 100%. Thienorphine also exhibited less inhibition on acetylcholine-induced contraction of GPI, with a maximum inhibition of 65%, compared with 93% inhibition by buprenorphine and 100% inhibition by morphine. Thienorphine induced a concentration-dependent decrease in the basal tonus of spontaneous movement of the GPI, the effect of which was weaker than that with buprenorphine. The duration of the effect of thienorphine on the GPI was longer than that with buprenorphine. Thienorphine had less influence, but a longer duration of action on GPI contraction and moderately inhibited intestinal transit.

The NOP receptor involvement in both withdrawal- and CCk-8-induced contracture responses of guinea pig isolated ileum after acute activation of κ-opioid receptor

In isolated guinea-pig ileum (GPI), the κ-opioid acute withdrawal response is under the control of several neuronal signaling systems, including the μ-opioid, the A1-adenosine and the CB1 receptors, which are involved in the inhibitory control of the κ-withdrawal response. After κ-opioid system stimulation, indirect activation of μ-opioid, A1-adenosine and CB1 systems is prevented by the peptide cholecystokinin-8 (CCk-8). In the present study, we have investigated whether the NOP system is also involved in the regulation of the acute κ-withdrawal response. Interestingly, we found that in GPI preparation, the NOP system is not indirectly activated by the κ-opioid receptor stimulation, but instead this system is able by itself to directly regulate the acute κ-withdrawal response. Specifically, our results clearly highlight first the existence of an endogenous tone of the NOP system in GPI, and second that it behaves as a functional anti-opioid system. We also found that, the NOP receptor system is involved in the regulation of the CCk-8-induced contracture intensity, only when in the presence of the κ-opioid receptor stimulation. This effect seems to be regulated by an activation threshold mechanism. In conclusion, the NOP system could act as neuromodulatory system, whose action is strictly related to the modulation of both excitatory and inhibitory neurotransmitters released in GPI enteric nervous system.

Synthesis and biological evaluation of N 1,N 2-bis-[4-(t-amino)-2-butynyl]phthalamides as oxotremorine and acetylcholine antagonists

A series of N1,N2-bis-[4-(t-amino)-2-butynyl]phthalamides have been synthesized and investigated for the blocking of the motor effect of oxotremorine in intact mice and for their antagonistic activity towards acetylcholine on isolated guinea pig ileum preparations. All N1,N2-bis-[4-(t-amino)-2-butynyl]phthalamides showed more selectivity as oxotremorine antagonists than atropine and less potent than atropine on peripheral cholinergic antagonistic activity.

Synthesis and pharmacological investigation of novel 2-substituted-3-carboxamido-4H-pyrimidobenzothiazole derivatives as a new class of H1-antihistaminic agent

With the aim of developing potential H1-antihistaminic agents, a series of novel 2-substituted-3-carboxamido-4-oxo-4H-pyrimido[2,1-b][1,3]benzothiazole (8a–g) and 2-substituted-3-carboxamido-8-chloro-4-oxo-4H-pyrimido[2,1-b][1,3]benzothiazole (9a–g) were synthesized and evaluated in vitro for H1-antihistaminic activity on guinea pig ileum preparation. IC50 values of the compounds were found to be in the micromolar range. Chlorpheniramine maleate was used as a standard drug. The active derivatives (8d–8g and 9d–9g) were found to have IC50 values comparable to reference standard chlorpheniramine maleate. The sedative potential of both series (8a–g and 9a–g) is less than the reference drug. Hence, it could serve as prototype molecules for further development as a new class of H1-antihistaminic agents.

Assessment of the pharmacological properties of 5-methoxyindole derivatives at 5-HT4 receptors

The aim was to examine the biological activity of 5-methoxytryptamine derivatives at the 5-hydroxytryptamine (5-HT)(4) receptor to explore the effect of substitution on the aliphatic amine of the 5-methoxyamine scaffold. Three compounds were tested for affinity at the 5-HT(4) receptor by radioligand binding and functional activity using guinea-pig ileum and human colon circular muscle preparations and also in the mouse whole gut transit test. The three compounds all had agonist properties at the 5-HT(4) receptor but their efficacy differed in the different functional tests. Compound 3 had the highest affinity for the 5-HT(4) receptor and was a full agonist at relaxing human colon circular muscle with efficacy closest to 5-HT. Compounds 1 and 2 were partial agonists in this assay with lower efficacies; compound 2 was a full agonist in the guinea-pig ileum assay whereas compound 3 was a partial agonist. Compounds 1 and 2 also showed activity in the mouse gut transit assay while compound 3 had no activity. Of the compounds tested, compound 3 was the most promising 5-HT(4) receptor agonist and the results highlight the value of using human tissue in functional tests when assessing compounds for potential activity.

Gastroprotective Effect and Safety Assessment of &lt;i&gt;Zanthoxylum Zanthoxyloides&lt;/i&gt; (Lam) Waterm Root Bark Extract

Problem statement: Gastrointestinal ulcers account significantly for morbidity and mortality in Ghana. The study therefore investigate d the gastroprotective effect of an ethanolic root bark extract of Zanthoxylum zanthxyloides and its safety for us. Approach: Gastric ulceration was induced in Sprague-Dawley rats with Indomethacin (25 mg kg -1 , p.o) and was treated with 150, 250, or 500 mg kg -1 of the extract, or 20 mg kg -1 Esomeprazole. The number of ulcers per stomach, Ulcerative Index and Curative Ratio were determined. A histolo gical study of the gastric mucosa was also performed. The extract's effect on an isolated guin ea-pig ileum preparation was investigated to elucidate its possible mechanism of action. Safety assessments involving, organ weight to body weight ratio determination, hematological analysis and liv er function tests were performed. Results: The extract significantly decreased (p ≤0.001) the number of ulcers per stomach and the Ulc erative Index (similar to Esomeprazole) and significantly increas ed (p ≤0.001) the Curative Ratio in a dose-dependent manner. It completely corrected the architectural d istortions caused by gastric ulceration and inhibit ed significantly (p ≤0.001) the contractile responses of the isolated gu inea-pig ileum to Acetylcholine, Nicotine and Histamine in a manner comparable to reference antagonists. The extract had no significant effect (p>0.05) on organ weight to body ratio and hematological profile. Plasma levels of Alanine transaminase and Alkaline phosphatase decreased significantly (p ≤0.001) in extract and Esomeprazole-treated ulcerated rats. Levels of Gamma-glutamyl transferase , Total bilirubin (direct and indirect) however increased significantly (p≤0.01-0.001). Conclusion/Recommendations: Per the findings, the ethanolic root bark extract of Zanthoxylum zanthoxyloides has gastroprotective effect in Sprague-Dawley rats working possibly via antimuscarinic or antihistaminic mechanism. It however has a potential of causing cholestasis hence liver func tion should be monitored.

General Pharmacology Studies on ß-Domain Deleted Recombinant Factor VIII

beta-Domain deleted recombinant factor VIII (GC-rAHF), newly developed by Korea Green Cross Co., is a novel therapeutic for hemophiliacs and is currently under clinical evaluation. The general pharmacological properties of this drug were evaluated using mice, rats, guinea pigs and rabbits. Intravenous doses of 5 to 500 IU/kg were assayed in several tests to analyze their effects in vivo on various systems. The effect of the substance under study was also tested in vitro on isolated guinea pig ileum preparations at final concentrations of 5 to 50 IU/kg. The result of this study showed that GC-rAHF did not affect general behavior in the Irwin test. Similarly the drug was not found to affect neither normal body temperature nor the spontaneous activity in mice. In addition, it was not found to induce pharmacologically significant alterations of the cardiovascular and respiratory parameters in rats. No effects were observed either in the pentobarbital sodium-induced sleep-induction time and duration, in writhing test or in the test of pentetrazole-induced convulsion. Finally, the tested drug did not modify the gastrointestinal motility, acetylcholine or histamine-induced contraction of the isolated guinea pig ileum, nor gastric secretion. The results demonstrated that GC-rAHF has no effects on the central nervous, cardiovascular, respiratory and digestive systems in the doses of 5, 50 and 500 IU/kg in vivo and 5, 10, 50 and 100 IU/kg in vitro.

Pharmacological mechanisms underlying the antinociceptive and tolerance effects of the 6,14-bridged oripavine compound 030418.

To investigate possible pharmacological mechanisms underlying the antinociceptive effect of and tolerance to N-methyl-7α-[(R)-1-hydroxy-1-methyl-3-(thien-3-yl)-propyl]-6,14-endo-ethanotetrahydronororipavine (030418), a derivative of thienorphine. The binding affinity and efficacy of 030418 were determined using receptor binding and guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) assays in CHO-μ, CHO-κ, CHO-δ, and CHO-ORL1 cell membranes. The analgesic activity of and tolerance to 030418 were evaluated in thermal nociceptive tests in mice. The effects of 030418 on opioid receptors were further investigated using in vivo pharmacological antagonist blockade and in vitro tissue preparations. The compound 030418 displayed high binding affinity to all subtypes of opioid receptors with K(i) values in the nanomolar range. In [(35)S]GTPγS binding assay, the maximal stimulation of 030418 to μ-, κ-, δ-receptors and the ORL1 receptor was 89%, 86%, 67% and 91%, respectively. In hot-plate test, the antinociceptive effect of 030418 was more potent and longer than morphine. The nonselective opioid receptor antagonist naloxone could completely block 030418-induced antinociception, while both the μ-opioid receptor antagonist β-FNA and the κ-opioid receptor antagonist nor-BNI attenuated 030418-induced antinociception. In contrast, the ORL1 receptor antagonist J-113397 enhanced the antinociceptive effect of 030418. Additionally, chronic treatment with 030418 resulted in a dramatic development of tolerance that could not be effectively prevented by J-113397. In guinea pig ileum preparation, the existing action of 030418 could be removed with difficulty after prolonged washing. The compound 030418 is a novel agonist of opioid receptors with high efficiency, long-lasting effect and liability to tolerance, which may be closely correlated with the methyl group at the N(17) position and the high hydrophobicity of the C(7)-thiophene group in its chemical structure.

Biphasic regulation of the acute μ-withdrawal and CCk-8 contracture responses by the ORL-1 system in guinea pig ileum

The cloning of the opioid-receptor-like receptor (ORL-1) and the identification of the orphaninFQ/nociceptin (OFQ/N) as its endogenous agonist has revealed a new G-protein-coupled receptor signalling system. The structural and functional homology of ORL-1 to the opioid receptor systems has posed a number of challenges in the understanding the often competing physiological responses elicited by these G-protein-coupled receptors. We had previously shown that in guinea pig ileum (GPI), the acute μ-withdrawal response is under the inhibitory control of several systems. Specifically, we found that the exposure to a μ-opioid receptor agonist activates indirectly the κ-opioid, the A 1-adenosine and the cannabinoid CB 1 systems, that in turn inhibit the withdrawal response. The indirect activation of these systems is prevented by the peptide cholecystokinin-8 (CCk-8). In the present study, we have investigated whether the ORL-1 system is also involved in the regulation of the acute μ-withdrawal response. Interestingly, we found that in GPI preparation, the ORL-1 system is not indirectly activated by the μ-opioid receptor stimulation, but instead the system is able by itself to directly regulate the acute μ-withdrawal response. Moreover, we have demonstrated that the ORL-1 system behaves both as anti-opioid or opioid-like system based on the level of activation. The same behaviour has also been observed in presence of CCk-8. Furthermore, in GPI, the existence of an endogenous tone of the ORL-1 system has been demonstrated. We concluded that the ORL-1 system acts as a neuromodulatory system, whose action is strictly related to the modulation of excitatory neurotrasmitters released in GPI enteric nervous system.