Calcium handling in a testosterone responsive skeletal muscle of the MDX mouse

Muscle necrosis in Duchenne muscle dystrophy (DMD) and in the mdx mouse has been related to abnormal calcium homeostasis associated with the lack of dystrophin. We have previously shown that the testosterone-dependent levator ani (LA) muscle of the mdx mouse develops a mild muscle wasting and fiber degeneration compared to the less hormone sensitive diaphragm (DIA) muscle, suggesting a protective effect of androgens. This study assessed the calcium handling mechanisms and cytosolic calcium concentration ([Ca2+]i) in LA muscles of mdx mice at critical stages of muscle disease. Muscle contractures induced by caffeine and 4-chloro-m-cresol (4-CmC), two activators of ryanodine channels, were recorded in LA and DIA muscles of prepubertal (1 month-old), adult (4 month-old) and aged (18 month-old) wild-type (wt) and mdx mice. [Ca2+]i was estimated with the fura-2 fluorescent dye in enzymatically dissociated LA muscle fibers of the same wt and mdx groups. Tetanus tension (TT) in the LA increased proportionately to the muscle weight (4 to 5-fold), but specific TT (TT/mg) did not differ among age-matched wt and mdx groups. Muscle contractures induced by caffeine (3-100 mM) or 4-CmC (0.1-5.0 mM) in the LA were greater in prepubertal than in adult and aged mice, but they did not differ among age-matched wt and mdx groups. The resting [Ca2+]i in mdx LA muscle fibers was not significantly affected at any age. Comparatively, dystrophic DIA presented reduced muscle strength in adult (40%) and aged (45%) mice, whereas the muscle responses to caffeine increased with age (63 to 82%), indicating changes in the Ca2+ handling mechanisms. The results indicated that muscle strength and calcium homeostasis in dystrophic LA muscle fibers were not significantly altered, confirming previous evidence of androgens’ beneficial effects on hormone-sensitive skeletal muscles.

Antinociceptive and antiinflammatory activities of the aqueous extract and isolated Cuphea carthagenensis (Jacq.) J. F. Macbr.

The aqueous extract (AE) and isolated fraction (ppt-3) of Cuphea carthagenensis (Jacq.) J. F. Macbr (sete-sangrias) were tested using models of nociception and inflammation in mice. Oral administration (p.o.) of the AE (10 to 100 mg/kg) and fraction ppt-3 (0.1 to 10 mg/kg) reduced the acetic acid-induced writhing in mice by 40 to 50 percent and by 46 to 70 percent of control, respectively. At the same doses AE and ppt-3 did not affect the tail flick response. Fraction ppt-3 also reduced the carrageenininduced paw edema, but at a dose 1000 times higher than that inducing antinociception. The results indicated the presence in the plant of antinociceptive constituents devoid of antiinflammatory activity, with actions apparently mediated by non-opioid mechanisms.

Natural probes for cholinergic sites: L-bebeerine actions on the neuromuscular transmission, the nicotinic receptor/ionic channel complex, and contraction of skeletal muscles

The mechanisms underlying the muscle relaxant of 1-bebeerine (BB), a tertiary alkaloid isolated from the roots of Chondrodendron platyphyllum, were examined in mammalian and amphibian skeletal muscles. Injections of BB (0.05 - 1 g/kg,i.p.) in rats caused a dose-related flaccid paralysis and respiratory arrest at high doses. In isolated rat diaphragmand toad sartorius muscles, BB depressed the indirectly elicited muscles twitches (IC50:228 muM and 5.4 muM, respectively, at 22 degree) and blocked the nerve-elicited muscle action potential. The neuromuscular blockade was not reserved by neostigmine (10 muM). High concentrations of BB (170 and 340 muM) caused muscle contracture unrelated to the junctional blockade, and intensified by increasing the bath temperature. Analysis of the contraction properties showed that BB (40 and 80 muM)increaded the twitch/tetanus ratio (46 percent and 125 percent) and prolonged the relaxation time; the falling phase of the directly elicited action potential in toad sartorius muscle fibers was slower probably by a decreased potasium conductance. BB (0.1 - 340 muM) reduced the binding of [1251]alpha- -bungarotoxin to the junctional AACh receptor of the rat diaphragm (IC50:47.7 muM, at 37 degree. At low concentrations BB (1.5 - 15 muM) induced either opening or blockade of the Ach receptor-ionic channel. The results showed that BB blocked noncompetitively the neuromuscular transmission through a mechanism that affects the Ach recognition site and the ionic channel properties. The alkaloid also produced muscle contracture and changed the contractile properties through its extra-junctional action at the calcium handling by the sarcoplasmic reticulum or the contractile machinery.

Analgesic and anti-inflammatory screening of two Brazilian medicinal plants: a positive and a false-positive result

Medical plants used in Brazilian folk medicine to treat pain and inflammation constitute 20 per cent of the current publications on plants in the country. The experimental methods to screen these activities, however, are frequently influenced by previous conditions of the animals and other properties of the tested material unrelated to their putative effects. An example is herein reported on studies carried out with two plants reputed for their anti-inflammatory activities: Scoparia dulcis L. collected in Sao Luis, state of Maranhao and Piper marginatum Jacq. collected in Recife, state of Pernambuco. The aerial parts were extracted in hot water, the extracts concentrated and freeze-dried. Previous treatment of rats with either water (0.5 and 1 g/Kg, p.o), decreased the edema produced by carrageenin in the rat paw (40 per cent and 70 per cent), but only the extracts of S. dulcis inhibited the exudate and leukocyte migration induced by carrageenin in the rat pleurisy model (by 60 per cent and 70 per cent, respectively). The ethanolic extract of S. dulcis was more active than the water extract. All extracts reduced the acetic acid induced writhing in mice (by 20 to 60 per cent), the S. dulcis extract being more potent than that of P. marginatum. Both extracts, however, were ineffective in the tail flick test. Intravenous injection of either extract induced hypertension in both anesthetized and unanesthetized rats, but only P. marginatum produced hypertension after oral administration. This effect was blocked after treatment with prazosin (1 mg/Kg). In the isolated rat vas deferens the aqueous and purified extracts induced contractions parallel to those produced by noradrenaline (10(-8) - 10(-4) M) which were blocked by prazosin (10(-7) M). Contractions of electrically paced rat left atria preparations were pontentiated in the presence of either extract (by 30 to 220 per cent), the effect being blocked buy propranolol (2muM). High performance liquid chromatographic analysis of purified hypertensive fractions revealed the presence of both adrenaline and noradrenaline in both extracts. The results indicated that only the S. dulcis extracts presented analgesic/anti-inflammatory effects unrelated to vasoconstriction induced by both catecholamines. The effects obtained upon injection of P. marginatum extracts were unspecific and correlated with the general sympathomimetic effects produced by the extract.

Efeitos do tratamento cronico de ratos com o extrato de Chamaecrista nictans Irwin and Barneby na eliminacao de calculos renais / Effects of chronic treatment of rats with Chamaecrista nictans Irwin and barneby on eliminition of renal calculli

Chamaecrista nictans subs. patellaria var. ramosa Irwin and Barneby (Cassia patellaria DC), tambem conhecida pelo nome popular de peninha, e uma erva daninha originaria do Brasil cujo cha e utilizado na medicina popular para eliminacao de calculos renais. O ensaio farmacologico foi feito a fim de testar o efeito do tratamento cronico com extrato fluido da planta, na urolitiase experimental em ratos atraves da inducao de calculo vesical. Os resultados indicam que o extrato fluido da peninha nao apresentou atividade antilitiasica no modelo experimental testado

Inhibition of gastric secretion by a water extract from Baccharis triptera, Mart

Baccharus triptera Mart, is a widespread Compositae used in Brazilian folk medicine to treat gastrointestinal disturbances, rheumatic disease, mild fever, diabetes and as an anti-helminthic. Water extract of small branches of the plant (WE) administered to mice and rats (0.1 to 2 g/Kg, p.o) did not alter spontaneous motor activity, sleeping time induced by barbiturates or the tailflick response in mice. The extract decreased by 40 por cento the number of writhings induced by 0.8 por cento scetic acid, i.p., but did not influence paw edema induced by carrageenan or dextran in rats WE (2g/Kg, p.o.) decreased the intestinal transit of charcoal in mice by 20//. Gastric secretion in pylorus ligated rats was reduced after treatment with WE (1 and 2 g/Kg. i.p. or intraduodenal and the gastric pH was raised. The extract (1 g/Kg, p.o.) prevented gastric ulcers induced in rats by immobilization at 4ºC, but not those induced by indomethacin (10 mg/Kg, s.c.). The results indicate that WE may relieve gastrointestinal disorders by reducing acid secretion and gastrointestinal hiperactivity. Neither analgesic nor anti-inflammatory activities were detectable. .

The water extract of Coleus barbatus Benth decreases gastric secretion in rats

Coleus barbatus (Labiatae) Benth is popularly used in Brazil "for the healing of liver and stomach diseases". The water extract (WE 1 to 10 g/Kg, p.o.) of stem and leaves given to rats and mice did not induce signs of intoxication. Preveious treatment of mice with WE (1 g/kg, p.o.) shortened the sleeping time induced by pentobarbital (50 mg/Kg, i.p.) by 37 por cento, althoyugh the extract alone did not increase the spontaneous activity nor did it induce hyperexcitability. In mice WE (2 g/Kg, p.o.) increased the intestinal transit of charcoal by 30 por cento, while reduced gastric secretions ion rats treated with WE (2g/Kg intraduodenal) 3,9 ± 1.0 to 0.5 ± 0.2 ml/4h, respectively). The treatment also reduced the total acid secretion from 34.4 ± 11.0 to 2.7 ± 0.5 mEq/l and raisedgastric pH from 2.2 ± 0.3 to 6.5 ± 0.8. Treatment with WE (2g/Kg, p.o.) protected against gastric ulcers induced by stress (5.3 ± 1.6 and 1.5 ± 0.5 ulcers/cm²), but did nor protect against indonethacin induced ulcers. The results show that the water extract of C barbatus Benth produces mild stimulation of thecentral nervous system and increases intestinal movements. The extract also reduces gastric secretion indicating an antidyspeptic activity, and protects against gastric ulcers induced by stress.

Pharmacological screening of Ageratum conyzoides L. (mentrasto)

The pharmacological activities of a water extract (WE) of Ageratum conyzoides L, a plant populary known for its analgesic and anti-inflamatory properties, were studied in vivo and in vitro preparations. Oral administration (p.o.) of the water extract (WE, 0.1 to 5 g/Kg) to rats and mice induced quietness and reduced the spontaneous motility. the sleeping time induced by sodium pentobarbital (50 mg/Kg, i.p.) in mice was not altered by previous treatment with We (2 g/Kg, p.o.). The same treatment did not influence the paw edema induced by carrageenan or dextran, nor did it reduce the chronic paw edema induced by complete Freund's adjuvant or formaldehyde in rats. The tail flick response in immersion test and writhings induced by 0.8%acetic acid in mice were not altered by WE either. In isolated guinea-pig ilea WE (0.4 to 4 mg/ml) did not alter the EC50 values of histamine or acetylcholine, but reduced the maximal response to the agonists by 20 to 50%. We (0.01 to 10 mg/ml) produced tonic contractions of the ileal smooth muscle proportional to the doses, reaching a maximum of 75% relatively to the maximum obtained with histamine. Those contractions were blocked by diphenhydramine (10 nM) and reduced by 32% in presence of atropine (10 nM). The results indicated that oral treatment of rodents with A. conyzoides L neither reduced the inflammatory edema nor did it decrease the reaction to pain stimuli. In vitro the extract presented an unexpected histamine-like activity characteristic of a partial agonist. The results did not confirm the popular medicinal indications of the plant.

Analgesic activity of a triterpene isolated from Scoparia dulcis L. (vassourinha)

Analgesic and anti-inflammatory activities of water (WE) and ethanolic (EE) extracts of Scoparia dulcis L. were investigated in rats and mice, and compared to the effects induced by Glutinol, a triterpene isolated by purification of EE. Oral adminsitration (p.o.) of either WE or EE (up to 2 g/Kg) did not alter the normal spontaneous activity of mice and rats. The sleeping time induced by sodium pentobarbital (50 mg/Kg, i.p.) was prolonged by 2 fold in mice pretreated with 0.5 g/Kg EE, p.o. Neither extract altered the tail flick response of mice in immersion test, but previous administration of EE (0.5 g/Kg, p.o.) reduced writhings induced by 0.8% acetic acid (0.1 ml/10 g, i.p.) in mice by 47% EE (0.5 and 1 g/Kg, p.o.) inhibited the paw edema induced by carrageenan in rats by respectively 46% and 58% after 2 h, being ineffective on the paw edema induced by dextran. No significant analgesic or anti-edema effects were detected in animals pretreated with WE (1 g/Kg, p.o.). Administration of Glutinol (30 mg/Kg, p.o.) reduced writhing induced by acetic acid in mice by 40% and the carrageenan induced paw edema in rats by 73%. The results indicate that the analgesic activity of S dulcis L. may be explained by explained by an anti-inflammatory activity probably related to the triterpene Glutinol.

Presença da acetilcolina no fruto da Solanum melongena L / Presence of acetylcholine in fruits of Solanum melongena

Apresentam-se os resultados do estudo do efeito colinomimético dos extratos aquosos do fruto de Solanum melongena L., Solanaceae, vulgarmente conhecida no Brasil como berinjela roxa. A presença de acetilcolina nos extratos foi determinada através do teste de pressäo arterial do rato, de preparaçöes de musculatura lisa e estriada e ainda de ensaios de incubaçäo do extrato com plasma humano. Os efeitos observados foram seletivamente bloqueados por atropina ou galamina e potenciados com prostigmina