Studies on the Anti-Inflammatory,Analgesic and Antipyrexic Activities of Betulinic Acid Derived from Tetracera Potatoria

Background

The anti-inflammatory and anti-nociceptive activity of betulinic acid (BA) was investigated in this study. The triterpene was isolated from the ethyl acetate extract of Tetracera potatoria and its structure was verified by IR and NMR spectroscopy. The bioactivity of this compound was assessed using carrageenan-induced paw oedema in rats and carrageenan-induced pulmonary oedema in mice for the anti-inflammatory activity, while acetic acid-induced writhing test in mice and zymosan-induced fever in rats were used for analgesic test.

Materials and Methods

Rats and mice were randomly divided into groups of five animals. For each experiment, betulinic acid at 10, 20 or 40mg/kg b.w was administered intraperitoneally to the first three groups respectively. The fourth group was administered with indomethacin (10mg/kg) or acetylsalicylic acid (150mg/kg), while the fifth group was administered with distilled water (10ml/kg). Data obtained were expressed as mean±S.E.M and significant differences were determined at p<0.05.

Results

BA significantly reduced carrageenan-induced paw oedema by 11.0%, 45.7%, 68.6% or pulmonary oedema by 25.6, 29.2 and 45.13% dose dependently. 40 mg/kg of BA inhibited paw oedema by 68.6% comparably to acetylsalicylic acid (71.4%) or indomethacin (51.33%) respectively. Abdominal writhing was also significantly (p<0.05) reduced to 17.20 writhes by BA (40mg/kg) comparable to Indomethacin (16.3writhes). Fever was inhibited by BA most significantly by 3hours post-injection of zymosan (1.00, 1.45, 0.00°C) and this inhibitory effect was higher than that observed for acetylsalicylic acid (0.30°C).

Conclusion

Betulinic acid derived from Tetracera potatoria exhibited potent anti-inflammatory, analgesic or antipyrexic activity which is comparable to indomethacin or acetylsalicyclic acid.     

Profile of central corneal thickness in diabetics with and without dry eye in a Saudi population

PurposeThe aim of this study was to determine the impact of diabetes in patients with and without dry eyes (DE) on central corneal thickness (CCT) measurements.MethodsEighty-six subjects (51 diabetics and 35 controls) participated in the study. Ultrasound pachymetry was used to measure the CCT, whereas tear break-up time (TBUT) and Schirmer tests were conducted for tear assessments. The participants were divided into group 1 (diabetics without DE), group 2 (diabetics with DE), and group 3 (nondiabetics controls). The measurements were compared using analysis of variance.ResultsThe mean (95% confidence interval [CI]) of CCT was 610 (599 to 620), 601 (582 to 618), and 583 (576 to 589) μm, respectively, in diabetics without DE, with DE, and the control groups. There was significant difference in mean CCT between diabetics without DE and controls (P < 0.0001), but no significant difference in diabetics with DE versus controls (P > 0.05). The mean (95% CI) values for TBUT and Schirmer tests were 14 (13 to 15), 6 (4 to 6), 14 (14 to 15) seconds, and 21 (19 to 23), 7 (6 to 8), and 20 (19 to 21) mm, respectively, for diabetics without DE, with DE, and the nondiabetic groups.ConclusionsDE affects the CCT in diabetic subjects, having a predilection for lower values in those exhibiting DE. In addition, the results also support the view that diabetics tend to present with higher CCT values when compared with nondiabetic patients.     

Studies on the expression and function of beta-3-adrenoceptors in the colon of rats with acetic acid-induced colitis.

Ulcerative colitis is characterized by dysfunctional motility. Our main objective in this investigation was to study the effect of an acetic acid-induced ulcerative colitis on the expression and function of beta(3)-adrenoceptors in the rat colon. Inflammation was induced by administering acetic acid intrarectally into rats. Levels of myeloperoxidase activity and beta(3)-adrenoceptor mRNA were measured in colon samples taken following acetic acid administration. Relaxation responses to beta(3)-adrenoceptor agonists were also studied. Ulcerative colitis was associated with significantly elevated levels of myeloperoxidase activity in the colon segments. Levels of beta(3)-adrenoceptor mRNA as well as the relaxation responses to isoprenaline and BRL 37344 were however not significantly different between inflamed and control tissue. Acetic acid-induced ulcerative colitis in rats was not associated with changes in the expression and/or function of beta(3)-adrenoceptors in the rat colon. Therefore, the dysfunctional motility that is characteristic of ulcerative colitis, is not likely to be due to changes in beta(3)-adrenergic mechanisms in this model.     

Effect of calcium withdrawal and agents affecting calcium translocation on agonist-induced contractions of the rabbit ovarian artery

The effect of extracellular calcium ion (Ca2+) depletion, diltiazem, D-600 and TMB-8 on potassium (K+), norepinephrine-(NE) and histamine-induced contractions of the rabbit isolated ovarian artery was studied. K+-induced contractions, which were biphasic, were rapidly lost (congruent to 5 min) when calcium was removed from the physiological saline solution (O-Ca2+ PSS). NE and histamine-induced contractions also declined rapidly under nominal O-Ca2+ conditions without any evidence of a depletion resistant component. However, after 1 h under these conditions there was a partial restoration of their responses. EGTA (10(-3) mol/l) abolished these contractions to NE and histamine but not those in normal PSS. Diltiazem and D-600 were more effective against K+-induced than NE- and histamine-induced contractions while the intracellular Ca2+ antagonist TMB-8 was equally effective against all three responses. Histamine could still evoke contraction of the K+-contracted ovarian artery after this had been completely abolished with diltiazem or D-600 but not TMB-8. These results are interpreted to suggest that K+, NE and histamine probably release intracellular Ca2+ to evoke contractions of the ovarian artery. They differ, however, in the mechanisms they employ to facilitate entry of extracellular calcium, which in turn leads to intracellular calcium release.     

EFFECT OF EXTRACELLULAR Mg CONCENTRATION ON ELECTRICALLY INDUCED CONTRACTIONS OF RAT VAS DEFERENS IN VITRO

Contraction of smooth muscles of the vas deferens plays an important role in the propulsion of sperm into the pelvic urethra. This study examined the influence of external Mg²⁺ concentration on reactivity of the rat vas deferens to electrical stimulation in vitro. Vasa deferentia isolated from adult male rats were set up in tissue baths containing physiological salt solution at 37°C and were stimulated electrically. Thereafter, increasing concentrations of Mg²⁺ were added to the bath and their effects on electrically evoked contractions were recorded. The effect of external Mg²⁺ depletion on evoked contractions was also examined. External Mg²⁺ depletion enhanced the contractile response to electrical stimulation while increasing external Mg²⁺ concentration inhibited the contractions. The inhibitory effect of Mg²⁺ was partially reversed by increasing extracellular Ca²⁺ concentration and was not additive with nifedipine. The results indicate that reactivity of the vas deferens to electrical stimulation is modulated by extracellular Mg²⁺ concentration. The possible relevance of these data to sperm transport through the vas deferens is discussed.     

Curcumin reverses attenuated carbachol-induced contraction of the colon in a rat model of colitis

Background- Curcumin ameliorates colitis whether it reverses colitis-induced reduction in colonic contractility remains to be investigated. Objectives- To investigate the effect of curcumin on colitis-induced reduction of carbachol-induced contraction in colon segments from rats treated with trinitrobenzenesulphonic acid. Methods- Colitis was induced in rats by intra rectal administration of trinitrobenzenesulphonic acid and followed for 5 days. A group of animals which received trinitobenzene sulphonic acids was treated with curcumin (100 mg/Kg and 200 mg/kg body weight) 2 hrs prior to induction of colitis. The controls received phosphate buffered saline in a similar fashion. Markers of inflammation and contractility of colon were assayed using standard procedures. Results- Induction of colitis was associated with increased myeloperoxidase activity and malondialdehyde levels, gross histological changes characterized by infiltration of inflammatory cells. All these changes were prevented by treatment with curcumin (100mg/kg). Treatment with curcumin also reduced the histological scores from 3.34±0.40 to 1.75±0.30 confirming an anti-inflammatory effect of curcumin in this experimental model of colitis. Colonic reactivity to carbachol was decreased in colitis affecting the maximum response but not sensitivity. Treatment with curcumin had no effect on sensitivity of the colon to carbachol in any of the preparations. Curcumin however reversed the decrease in carbachol-induced contraction associated with trinitrobenzenesulphonic acid treatment. The same dose of curcumin had no effect on either the potency of or the maximum response to carbachol in control rats. Tissue expression of NF-kB was increased in colon segments from trinitrobenzenesulphonic acid -treated rats and this was inhibited in rats treated with curcumin. Conclusions- Based on these findings it is concluded that curcumin prevented the reduction in carbachol-induced contraction in trinitrobenzenesulphonic acid -treated rats by modulating NF-kB signaling pathway.     

Lessons Learned from Glycemia Control Studies

Hyperglycemia occurs in patients with diabetes and in nondiabetic patients during acute illness. Epidemiologic and observational studies have demonstrated that hyperglycemia is associated with significant adverse outcomes. Nevertheless, studies evaluating the benefits of normalizing glycemia have produced inconsistent results. For instance, intensive control of hyperglycemia had been shown to provide microvascular benefit in type 1 and type 2 diabetic patients, but its macrovascular benefits had only been clearly demonstrated in type 1 diabetic patients. Moreover, although initial studies in critically ill patients showed decreased morbidity and mortality with tight glycemic control, subsequent studies yielded conflicting results. A series of recent studies provide further insight and show that intensive glycemic control in type 2 diabetic patients does provide macrovascular benefit but is associated with increased risk of hypoglycemia. In the critically ill patient, tight glycemic control could be detrimental; thus, a less aggressive glycemic target of 140 to 180 mg/dL is preferred.     

Variation in the interaction of some phenylethylamine and imidazoline derivatives with alpha-1 adrenoceptors in rabbit arteries: further evidence for the variable receptor affinity hypothesis.

This study was undertaken to determine whether the variation in the affinity of the alpha-1 adrenoceptors previously found for norepinephrine and phenylephrine in different arteries is also seen with other alpha-1 adrenoceptor agonists, and if so, if one part of the structure is particularly responsible for the variation. The potency and dissociation constants of eight agonists, both phenylethylamines and imidazolines, were determined in five rabbit arteries. In each artery the rank order of phenylethylamine agonist potency was epinephrine greater than norepinephrine greater than phenylephrine greater than deoxyepinephrine greater than methoxamine greater than dopamine. The same rank order of dissociation constants was found. For the imidazolines, the potency order was oxymetazoline greater than clonidine. For each agonist, there was a linear correlation between artery sensitivity and receptor affinity. None of the regression line slopes differed from each other. For each artery there was a linear correlation between phenylethylamine sensitivity and affinity. With the exception of the ovarian, which was lower, slopes of the regression lines in each group do not differ from each other. There were differences in the spread of the dissociation constants of the phenylethylamine derivatives among the arteries. The range of affinities was most marked with norepinephrine (greater than 40-fold) and least with epinephrine (approximately 4-fold). They suggest that agonist affinity governs the biological activity of at least the phenylethylamines on rabbit arteries mediated by the alpha-1 adrenoceptor. Variation in agonist affinity can explain the extent of the biological response. Differences in range of amine affinities in different arteries suggest that the agonist recognition site, although similar in the different arteries, is not identical and may be related particularly to some variation of the amine attachment site of the molecule. The results provide further support for the variable receptor affinity hypothesis.     

Effect of hyperbaric oxygen on guinea pig lens optical quality and on the refractive state of the eye

The main objective of this study was to investigate the effect of in vivo hyperbaric oxygen (HBO) treatment of albino guinea pigs on ocular refractive state and optical properties of the lens in vitro, as well as on the integrity of the mitochondria of the lens. The animals were treated 30-35 times (2.5-3 months) or 70 times (6 months) with HBO. An increased level of lens nuclear light scattering was evident by slit-lamp at 30 treatments, and this increased at 70 treatments. After 30-35 HBO treatments a myopic shift in refractive state of the eye was seen in two separate studies with two different refractionists. Also, the average back vertex distance of the lens was significantly shorter after 35 HBO treatments while spherical aberration (focal variability) increased after 70 treatments. No difference in refractive state was noted after 70 HBO treatments (a reversal of the initial myopic effect). The mitochondrial distribution and morphology of the lens epithelium and the superficial cortical fibre cells were normal after both 35 and 70 HBO treatments, highlighting that HBO treatment does not affect the superficial cortex of the lens. The results of the in vitro lens optical analysis carried out in this study correlate with the myopia observed after 30-35 HBO in vivo treatments. A similar reversible myopia and increase in lens nuclear light scattering is known to occur in humans treated with HBO for extended periods and the results suggest that the myopia was caused by a change in the refractive index of the lens. The significant loss of sharp focus after 70 HBO treatments can be correlated with previous reports of biochemical and morphological changes associated with HBO-induced loss of lens nuclear transparency in mature guinea pigs. The guinea pig HBO model may be a useful approach for the study of lens development and refractive error.     

Chloride channels and alpha1-adrenoceptor-mediated pulmonary artery smooth muscle contraction: effect of pulmonary hypertension

Noradrenaline induced concentration-dependent contractions of pulmonary artery segments from control and monocrotaline-treated rats. There was a significant decrease in the maximum response but not sensitivity in artery segments from monocrotaline-treated rats. At a concentration (10(-6) M) that abolished KCl-induced contraction, nifedipine attenuated but did not abolish, noradrenaline-induced contraction in both groups. However, noradrenaline-induced contraction in artery segments from pulmonary hypertensive rats was more susceptible to inhibition by nifedipine. Bumetanide (10(-4) M), a chloride transport inhibitor and niflumic acid, a chloride channel inhibitor, reduced noradrenaline-induced contraction of the pulmonary artery in control and pulmonary hypertensive groups. These compounds were more effective in ring segments from pulmonary hypertensive rats. It was concluded that activation of chloride channels was involved in noradrenaline-induced contraction and that the contribution of chloride channels was enhanced in pulmonary hypertensive rats.