Phenthonium, a quaternary derivative of (-)-hyoscyamine, enhances the spontaneous release of acetylcholine at rat motor nerve terminals.

1. A quaternary derivative of (-)-hyoscyamine, phenthonium (Phen) induced a concentration-dependent increase in the rate of spontaneous quantal release of acetylcholine (ACh) at the mammalian neuromuscular junction, as shown by intracellular recordings of the miniature endplate potentials (m.e.p.ps) in rat diaphragm muscles. 2. The prejunctional effect of Phen (10-50 microM) was reversible, unrelated to temperature (22 degrees-35 degrees C), unaltered by either changes in [Ca2+]o or by high [Mg2+]o, and was not induced by membrane depolarization. 3. Simultaneously, Phen reduced the amplitude of m.e.p.ps by a postjunctional action. 4. The muscarinic agonist oxotremorine did not prevent the increase in m.e.p.p. frequency induced by Phen. Cholinesterase inhibition with neostigmine potentiated the prejunctional effect induced by a low (20 microM) but not a high (50 microM) concentration of Phen. 5. The increase in m.e.p.p. frequency induced by Phen was not influenced by previous incubation with either atropine (0.01-10 microM) or (+)-tubocurarine (0.05-0.1 microM). Each antagonist however, intensified the postjunctional effect of Phen. 6. Phen (20 microM) did not influence the quantal contents of e.p.ps in cut-muscle preparations or in the presence of high [Mg2+]o. A high concentration of Phen (50 microM) increased the rundown of e.p.p. trains evoked at 10-50 Hz. 7. The results indicate that the facilitatory prejunctional action of Phen cannot be explained by an antimuscarinic activity. A possible interaction of the antagonist with putative prejunctional nicotinic cholinoceptors however, was not excluded.

Mechanism of neuromuscular blockade induced by phenthonium, a quaternary derivative of (-)-hyoscyamine, in skeletal muscles.

1. The mechanisms underlying the postjunctional blockade induced by phenthonium [N-(4-phenyl) phenacyl 1-hyoscyamine] were investigated in mammalian and amphibian muscles. This muscarinic antagonist was previously shown to enhance specifically the spontaneous acetylcholine (ACh) release at concentrations that blocked neuromuscular transmission. 2. In both rat diaphragm and frog sartorius muscles, phenthonium (Phen, 1-100 microM) depressed the muscle twitches elicited by nerve stimulation (IC50: 23 microM and 5 microM, respectively), and blocked the nerve-evoked muscle action potential. The neuromuscular blockade was not reversed after incubation with neostigmine. 3. Equal concentrations of Phen decreased the rate of rise and prolonged the falling phase of the directly elicited action potential in frog sartorius muscle fibres, indicating that the drug also affects the sodium and potassium conductance. 4. Phen (50 and 100 microM) protected the ACh receptor against alpha-bungarotoxin (BUTX) blockade in the mouse diaphragm allowing recording of endplate potentials and action potentials after 5 h wash with physiological salt solution. 5. Phen (10-100 microM) produced a concentration- and voltage-dependent decrease of the endplate current (e.p.c.), and induced nonlinearity of the current-voltage relationship. At high concentrations Phen also shortened the decay time constant of e.p.c (tau(e.p.c.)) and reduced its voltage sensitivity. 6. At the same range of concentrations, Phen also reduced the initial rate of [125I]-BUTX binding to junctional ACh receptors of the rat diaphragm (apparent dissociation constant = 24 microM), the relationship between the degree of inhibition and antagonist concentration being that expected for a competitive mechanism. 7. It is concluded that Phen affects the electrical excitability of the muscle fibre membrane, and blocks neuromuscular transmission through a mechanism that affects the agonist binding to its recognition site and ionic channel conductance of the nicotinic ACh receptor.

Blockade of acetylcholine release at the motor endplate by a polypeptide from the venom of Phoneutria nigriventer.

1. The mechanisms underlying the muscle relaxation effect of a fraction (PF3) isolated from the Phoneutria nigriventer spider venom were assessed on mouse diaphragm and chick biventer cervicis muscle preparations. 2. PF3 (0.25-4 micrograms ml-1) produced a concentration-dependent blockade of the nerve-elicited muscle twitch of the mouse diaphragm (IC50 = 0.8 micrograms ml-1) without affecting the directly induced muscle twitch. In similar preparations, the crude venom (1-10 micrograms ml-1) produced muscle contracture and blocked both the direct and indirectly induced muscle twitches. 3. In the chick biventer cervicis muscle, PF3 (1-5 micrograms ml-1) blocked the nerve stimulated muscle twitch (IC50 = 1.26 micrograms ml-1), but did not alter the postjunctional response to exogenous acetylcholine (ACh, 10 microM-10 mM). 4. PF3 (2-8 micrograms ml-1) reduced the frequency of miniature endplate potentials (m.e.p.ps) recorded intracellularly from the mouse diaphragm muscle fibers by 58 to 64%, and diminished the amplitude of m.e.p.ps by 20 to 40% of control. The relationship between log m.e.p.p. frequency and log [Ca2+]o was shifted rightwards in the presence of 4 micrograms ml-1 PF3. 5. Raising the frequency of m.e.p.ps with high K+ medium or theophylline (3 mM) did not prevent the toxin-induced depression of spontaneous ACh release. 6. The quantal content of e.p.ps (m), determined in cut-diaphragm muscle fibres, was reduced by 53% and 77% of control by 1 and 4 micrograms ml-1 PF3, respectively. At 1 microgram ml-1 the toxin shifted the relationship between log m and log [Ca2+]o towards higher values without apparent change of the slope. 7. E.p.p. trains elicited at 10 to 50 Hz in the presence of PF3 (1 microgram ml-1) exhibited irregular amplitudes and facilitation related to the frequency of nerve stimulation. 8. It is concluded that PF3 blocks neuromuscular transmission by acting prejunctionally and reducing the nerve-evoked transmitter release. The effect was related to a diminished Ca2+ entry into the nerve terminal associated with inhibition of exocytosis.

Evidence for activation of the tissue kallikrein-kinin system in nociceptive transmission and inflammatory responses of mice using a specific enzyme inhibitor.

The pharmacological activity of phenylacetyl-Phe-Ser-Arg-N-(2, 4-dinitrophenyl)-ethylenediamine (TKI), a tissue kallikrein specific inhibitor, was assessed using models of nociception and inflammation in mice. Injection of TKI (13.6 - 136 micromol kg(-1), i.p. or 41 - 410 micromol kg(-1), s.c.) produced a dose-related inhibition of the acetic acid-induced writhes (by 37 to 85% or 34 to 80%, respectively). The antinociceptive activity of TKI (41 micromol kg(-1), i.p.) was maximal after 30 min injection and lasted for 120 min. The effect was unaltered by pretreatment with naloxone (8.2 micromol kg(-1), s.c.) or bilateral adrenalectomy. TKI (41 and 136 micromol kg(-1), i.p.) produced a dose-related decrease of the late phase of formalin-induced nociception by 79 and 98%, respectively. At 136 micromol kg(-1), i.p., TKI also shortened the duration of paw licking in the early phase by 69%. TKI (41 and 136 micromol kg(-1), i.p.) also reduced the capsaicin-induced nociceptive response (by 51 to 79%). TKI (41 micromol kg(-1), i.p. or 410 micromol kg(-1), s.c.) reduced the oedematogenic response, from the second to the fifth hour after carrageenin injection by 36 to 30% or by 47 to 39%, respectively. Pretreatment with TKI (41 micromol kg(-1), i.p.) reduced the capsaicin-induced neurogenic inflammation in the mouse ear by 54%. It is concluded that TKI presents antinociceptive and antiinflammatory activities mediated by inhibition of kinin formation by tissue kallikrein in mice. The results also indicate that the tissue kallikrein-dependent pathway contributes to kinin generation in nociceptive and inflammatory processes in mice.

Diterpene from Baccharis trimera with a relaxant effect on rat vascular smooth muscle.

A bioassay monitored fractionation of a chloroform extract from the aerial parts of Baccharis trimera yielded a mixture that blocked the Ca2+-induced contractions of KCl- depolarized rat portal vein preparations. Pharmacological tests of two pure compounds isolated from the mixture revealed the dilactonic clerodane diterpene as the active compound.

Sympathomimetic effects of Scoparia dulcis L. and catecholamines isolated from plant extracts.

The herb Scoparia dulcis L. is used in Brazilian folk medicine to treat bronchitis, gastric disorders, haemorrhoids, insect bites and skin wounds, and in oriental medicine to treat hypertension. A previous study has shown that extracts of S. dulcis have analgesic and anti-inflammatory properties; in this work the sympathomimetic activity of an ethanolic extract of Scoparia dulcis L. has been investigated in rodent preparations in-vivo and in-vitro. Administration of the extract (0.5-2 mg kg-1, i.v.) to anaesthetized rats produced dose-related hypertension blocked by the alpha-adrenoceptor antagonist prazosin (1 mg kg-1). Partition of the extract in chloroform-water yielded an aqueous phase 20 times more potent than the extract; this produced hypertension in either reserpine-treated or pithed rats. In untreated and reserpine-treated rats the same fraction (1-3 x 10(3) micrograms mL-1) produced concentration-dependent contractions of the vas deferens musculature parallel to those obtained with noradrenaline (10(-8)-10(-4)M). Prazosin (10(-7)M) reduced the maximum contractile effect of the aqueous fraction, and shifted the concentration-response curves for noradrenaline to the right. The aqueous fraction (25 and 50 micrograms mL-1) increased the inotropism of electrically driven left atria of rats, the effect being blocked by propranolol (0.4 microgram mL-1). In preparations of guinea-pig tracheal rings the aqueous fraction (1-3 x 10(3) micrograms mL-1) relaxed the muscle contraction induced by histamine (10(-4) M) in proportion to the concentration. The effect was antagonized competitively by propranolol (1.5 microM). High-performance liquid-chromatographic analysis of the aqueous fraction revealed the presence of both noradrenaline and adrenaline in the plant extract. The results indicated that both catecholamines may account for the hypertensive and inotropic effects obtained after parenteral administration of S. dulcis extracts. This sympathomimetic activity is, however, unrelated to the previously reported analgesic and anti-inflammatory properties of the plant extract, but may explain its effectiveness upon topical application in the healing of mucosal and skin wounds.

Androgen regulation of the nicotinic acetylcholine receptor-ionic channel in a hormone-dependent skeletal muscle.

The trophic influence of testosterone on the nicotinic acetylcholine receptor-ionic channel (AChR) was studied in the levator ani (LA) muscle of adult male rats (120 days) intact (C) or gonadectomized when 90 days old (G). In the indirectly elicited muscle twitch, the LA from G rats was less sensitive to d-tubocurarine (0.1-1 microM) than control muscles (IC25: C = 0.30 microM, G = 0.46 microM). In G rats, the amplitude of neurally evoked endplate currents (EPC) was reduced by 70%, but the EPC time constant was not changed. Maximal junctional binding of [125I]alpha-bungarotoxin in the LA (C: 72.5 +/- 13.2 amol/endplate) was reduced by 1.8-fold in LA from G rats, with no change of the association rate constant (C: 5.64 +/- 1.29 10(6) M-1 min-1). The results indicate that testosterone deprivation reduces the junctional AChR density in the rat LA without modifying the binding properties of the receptor.

Early and late influences of testosterone on acetylcholinesterase activity of skeletal muscles from developing rats.

1. The influence of perinatal and pubertal gonadal androgens on acetylcholinesterase (AChE) activity was studied in the hormone-sensitive levator ani (LA) and extensor digitorum longus (EDL) muscles of adult male rats (105 days). 2. The hormone was withdrawn by gonadectomy at various ages and the effects on AChE and weight were compared with those induced by chronic denervation of both muscles from adult rats. 3. Gonadectomy of infantile (2-30 days) rats prevented LA muscle growth, and reduced total AChE activity to values similar to those found in denervated muscles (15% of control). The EDL muscles were slightly affected and only in rats castrated on the 2nd postnatal day. 4. When the rats were castrated at puberty (45 days), LA muscle weight and total AChE activity were reduced to 20% and 18% of control values, respectively. 5. Gonadectomy of adult (60 and 75 days) rats led to atrophy of the LA muscle (to 29% of control) and reduced the total AChE activity (to 40% of control). 6. AChE activity per unit weight was reduced by 30% in rats castrated from 5 to 20 days of age, and increased by 30% in both LA and EDL muscles from rats castrated in adulthood. Gonadectomy before puberty prevented total AChE in the LA from increasing above the levels detected in chronically denervated muscles. 7. Gonadectomy after puberty reduced total AChE of the LA but never to the extent caused by muscle denervation. 8. It is concluded that testosterone regulates AChE in the LA by early priming of the motoneuron and by pubertal stimulation of enzyme synthesis, the synthesis being dependent on intact innervation.

Phenthonium induces a transient increase of acetylcholine efflux from motor nerve terminals.

Phenthonium (10-50 microM), a quaternary derivative of 1-hyoscyamine, increases the frequency of miniature end-plate potentials (2-5 fold) and blocks the nicotinic receptor-ionic channel in skeletal muscles. When tested on rat diaphragms previously incubated with [3H]choline, phenthonium (50 microM) increased the spontaneous release of radiolabelled acetylcholine (ACh) from 11.6 +/- 6.4 to 110.5 +/- 40.2 x 10(3) dpm/g within 15 min. The effect was transient, declining to 24.6 +/- 14.7 after 50 min. Subsequent electrical stimulation still in the presence of phenthonium increased the efflux to 164.7 +/- 45.3. The fractional release relative to the level before stimulation did not differ from controls. Phenthonium (20 microM) did not increase the spontaneous ACh release but doubled the efflux induced by nerve stimulation. The present results, compared to previous electrophysiological findings, indicate that quantal and nonquantal release are increased by phenthonium. They also show that the transient effect is not due to ACh depletion in nerve terminals.

The pharmacological effect of Bothrops neuwiedii pauloensis (jararaca-pintada) snake venom on avian neuromuscular transmission.

The neuromuscular effects of Bothrops neuwiedii pauloensis (jararaca-pintada) venom were studied on isolated chick biventer cervicis nerve-muscle preparations. Venom concentrations of 5-50 micro g/ml produced an initial inhibition and a secondary increase of indirectly evoked twitches followed by a progressive concentration-dependent and irreversible neuromuscular blockade. At venom concentrations of 1-20 micro g/ml, the responses to 13.4 mM KCl were inhibited whereas those to 110 micro M acetylcholine alone and cumulative concentrations of 1 micro M to 10 mM were unaffected. At venom concentrations higher than 50 micro g/ml, there was pronounced muscle contracture with inhibition of the responses to acetylcholine, KCl and direct stimulation. At 20-24 degrees C, the venom (50 g/ml) produced only partial neuromuscular blockade (30.7 +/- 8.0%, N = 3) after 120 min and the initial inhibition and the secondary increase of the twitch responses caused by the venom were prolonged and pronounced and the response to KCl was unchanged. These results indicate that B.n. pauloensis venom is neurotoxic, acting primarily at presynaptic sites, and that enzyme activity may be involved in this pharmacological action.

Timbós: ichthyotoxic plants used by Brazilian Indians.

The pharmacology of serjanosides, active principles isolated from the fish-poison plant Serjania lethalis St. Hil, a Sapindaceae, was investigated by comparing their actions in fishes and mammals with those of rotenone and certain saponins. The ichthyocid activity of the serjanosides was 2.5 times greater than that of the crude plant extract, approximately 10 times lower than the activity of rotenone, but from 10 to 50 times greater than the activity of the other saponins. When injected in mammals, the serjanosides induced deep prostration, dyspnea, cyanosis, ectopic heart beats, cardiovascular failure and respiratory arrest. These effects, leading to death that was not prevented by artificial respiration, indicated several mechanisms for the toxic action of the serjanosides. In vitro studies with these substances have shown that membrane depolarization and muscle contracture were probably due to unspecific surface actions. Rotenone, under the same experimental conditions induced hypotension, bradycardia and respiratory arrest. Death was prevented by artificial respiration. Ectopic foci, membrane depolarization, contractures and neuromuscular block were not observed after rotenone. Apparently, death from rotenone poisoning was a consequence of respiratory failure of central origin. The serjanosides are rather potent fish poison saponins. Mammals, however, are apparently insensitive to the same specific action since other toxic effects induced by those substances in rats and mice were also observed by employing saponins devoid of fish-killing activity.

Evaluation of the antiurolithiatic activity of the extract of Costus spiralis Roscoe in rats.

The antiurolithiatic activity of the water extract of Costus spiralis Roscoe was tested on formation of calculi on implants of calcium oxalate crystals or zinc disc in the urinary bladder of rats. The plant is a species from the family Zingiberaceae used in Brazilian folk medicine in urinary affections and for expelling urinary stones. Implantation of the foreign body in the urinary bladder of adult rats induced formation of urinary stones and hypertrophy of the smooth musculature. Oral treatment with the extract of Costus spiralis Roscoe (0.25 and 0.5 g/kg per day) after 4 weeks surgery reduced the growth of calculi, but it did not prevent hypertrophy of the organ smooth musculature. The contractile responses of isolated urinary bladder preparations to the muscarinic agonist bethanecol, in the presence and absence of the extract (0.3-3 mg/ml) or atropine (0.3-3 nM) did not differ among the experimental groups. The results indicate that the extract of Costus spiralis Roscoe is endowed with antiurolithiatic activity confirming thus folk information. The effect, however, was unrelated to increased diuresis or to a change of the muscarinic receptor affinity of the bladder smooth musculature to cholinergic ligands.

Altered acetylcholine release in the hippocampus of dystrophin-deficient mice.

Mild cognitive impairments have been described in one-third of patients with Duchenne muscle dystrophy (DMD). DMD is characterized by progressive and irreversible muscle degeneration caused by mutations in the dystrophin gene and lack of the protein expression. Previously, we have reported altered concentrations of α7- and ß2-containing nicotinic acetylcholine receptors (nAChRs) in hippocampal membranes of dystrophic (mdx) mice. This suggests that alterations in the central cholinergic synapses are associated with dystrophin deficiency. In this study, we examined the release of acetylcholine (ACh) and the level of the vesicular ACh transporter (VAChT) using synaptosomes isolated from brain regions that normally have a high density of dystrophin (cortex, hippocampus and cerebellum), in control and mdx mice at 4 and 12months of age. ACh release evoked by nicotinic stimulation or K(+) depolarization was measured as the tritium outflow from superfused synaptosomes preloaded with [(3)H]-choline. The results showed that the evoked tritium release was Ca(2+)-dependent and mostly formed by [(3)H]-ACh. ß2-containing nAChRs were involved in agonist-evoked [(3)H]-ACh release in control and mdx preparations. In hippocampal synaptosomes from 12-month-old mdx mice, nAChR-evoked [(3)H]-ACh release increased by 57% compared to age-matched controls. Moreover, there was a 98% increase in [(3)H]-ACh release compared to 4-month-old mdx mice. [(3)H]-ACh release evoked by K(+) depolarization was not altered, while the VAChT protein level was decreased (19%) compared to that of age-matched controls. In cortical and cerebellar preparations, there was no difference in nAChR-evoked [(3)H]-ACh release and VAChT levels between mdx and age-matched control groups. Our previous findings and the presynaptic alterations observed in the hippocampi of 12-month-old mdx mice indicate possible dysfunction of nicotinic cholinergic synapses associated with dystrophin deficiency. These changes may contribute to the cognitive and behavioral abnormalities described in dystrophic mice and patients with DMD.

Presence of mRNA of muscle nicotinic acetylcholine receptor subunits and an epsilon-subunit splice variant in the mouse brain.

Transcripts encoding for alpha1, beta1, delta, gamma and epsilon (and its splice variant epsilon(s)) subunits of the muscle-type nicotinic acetylcholine receptor (nAChR) were assessed using reverse transcription followed by polymerase chain reaction (RT-PCR) assays, with RNA extracted from the mouse skeletal muscle (diaphragm) and brain regions (cortex, hippocampus and cerebellum). The presence of alpha1, beta1, delta, gamma, epsilon and epsilon(s) transcripts was confirmed in the diaphragm muscle, used as positive control. mRNAs coding for muscle alpha1, beta1, delta, epsilon, epsilon(s), but not gamma subunits, were detected in adult mouse brain regions. An epsilon-subunit sequence variant, named epsilon(t), was also detected in all brain regions examined, but not in skeletal muscle. This new epsilon-subunit splice variant lacks a 115 bp cassette corresponding to exon 8 in the first intracellular transmembrane domain of the subunit, leading to a truncated protein. The data provide evidence for the presence of muscle-type nAChR subunits in the mouse central nervous system.

Anti-secretory, anti-inflammatory and anti-Helicobacter pylori activities of several fractions isolated from Piper carpunya Ruiz & Pav.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Piper carpunya Ruiz & Pav. (syn Piper lenticellosum C.D.C.) (Piperaceae), are widely used in folk medicine in tropical and subtropical countries of South America as an anti-inflammatory, anti-ulcer, anti-diarrheal and anti-parasitical remedy as well as an ailment for skin irritations. AIMS OF THE STUDY: To study the anti-inflammatory, anti-secretory and anti-Helicobacter pylori activities of different fractions isolated from an ethanolic extract of the leaves of Piper carpunya, in order to provide evidence for the use of this plant as an anti-ulcer remedy. Moreover, to isolate the main compounds of the extract and relate their biological activity to the experimental results obtained with the fractions. MATERIALS AND METHODS: Sixteen fractions were obtained from the ethanolic extract (F I-XVI) and 16 pure compounds were isolated and identified from these fractions. We studied the effects of the fractions (0.1-400microg/mL) on the release of myeloperoxidase (MPO) enzyme from rat peritoneal leukocytes, on rabbit gastric microsomal H(+), K(+)-ATPase activity and anti-Helicobacter pylori anti-microbial activity using the microdilution method (MM). The main compounds contained in the fractions were isolated and identified by (1)H- and (13)C NMR spectra analysis and comparison with the literature data. RESULTS: Eight fractions showed inhibition of MPO enzyme (F I-IV, X, XII, XIV and XV). The highest inhibition was observed with F XIV (50microg/mL, 60.9%, p<0.001). F X and XII were the most active ones, inhibiting the gastric H(+), K(+)-ATPase activity with IC(50) values equal to 22.3microg/mL and 28.1microg/mL, respectively. All fractions, except F XV, presented detectable anti-Helicobacter pylori activity, with a diameter of inhibition zones ranging from 11mm up to 50mm. The best anti-Helicobacter pylori activity was obtained with F III and V. Both fractions killed Helicobacter pylori with lowest concentration values, about 6.25mug/mL. Sixteen pure compounds were isolated, five of them are flavonoids that possess strong anti-oxidant and free radical scavenging activity, e.g. vitexin, isovitexin, and rhamnopyranosylvitexin. Terpenoids like sitosterol, stigmasterol and phytol, which have shown gastroprotective activity, and dihydrochalcones, like asebogenin, with anti-bacterial activity, were also isolated. Furthermore, the rare neolignan 1, that is a DNA polymerase beta lyase inhibitor, and (6S, 9S)-roseoside, that shows strong anti-bacterial activity, were isolated, for the first time, from the genus Piper. CONCLUSIONS: We suggest that the flavonoids isolated from F I and II (vitexin, isovitexin, rhamnopyranosylvitexin and isoembigenin) contribute to the anti-MPO activity, as well as to their anti-Helicobacter pylori activity. These flavonoids may also be responsible for the important inhibition of H(+), K(+)-ATPase activity. Also the phytosterols and phytol obtained from F XIV and XV could be involved in these gastroprotective activities. These results encourage us to continue phytochemical studies on these fractions in order to obtain full scientific validation for this species.

Inhibition of gastric acid secretion by a standardized aqueous extract of Cecropia glaziovii Sneth and underlying mechanism.

Cecropia glazioui Sneth (Cecropiaceae) is used in folk medicine in tropical and subtropical Latin America as cardiotonic, diuretic, hypotensive, anti-inflammatory and anti-asthmatic. The hypotensive/antihypertensive activity of the plant aqueous extract (AE) and isolated butanolic fraction (BuF) has been confirmed and putatively related to calcium channels blockade in vascular smooth musculature [Lapa, A.J., Lima-Landman, M.T.R., Cysneiros, R.M, Borges, A.C.R., Souccar, C., Barreta, I.P., Lima, T.C.M., 1999. The Brazilian folk medicine program to validate medicinal plants - a topic in new antihypertensive drug research. In: Hostettman, K., Gupta, M.P., Marston, A. (Eds.), Proceedings Volume, IOCD/CYTED Symposium, Panamá City, Panamá, 23-26 February 1997. Chemistry, Biological and Pharmacological Properties of Medicinal Plants from the Americas. Harwood Academic Publishers, Amsterdam, pp. 185-196; Lima-Landman, M.T., Borges, A.C., Cysneiros, R.M., De Lima, T.C., Souccar, C., Lapa, A.J., 2007. Antihypertensive effect of a standardized aqueous extract of Cecropia glaziovii Sneth in rats: an in vivo approach to the hypotensive mechanism. Phytomedicine 14, 314-320]. Bronchodilation and antidepressant-like activities of both AE and BuF have been also shown [Delarcina, S., Lima-Landman, M.T., Souccar, C., Cysneiros, R.M., Tanae, M.M., Lapa, A.J., 2007. Inhibition of histamine-induced bronchospasm in guinea pigs treated with Cecropia glaziovi Sneth and correlation with the in vitro activity in tracheal muscles. Phytomedicine 14, 328-332; Rocha, F.F., Lima-Landman, M.T., Souccar, C., Tanae, M.M., De Lima, T.C., Lapa, A.J., 2007. Antidepressant-like effect of Cecropia glazioui Sneth and its constituents -in vivo and in vitro characterization of the underlying mechanism. Phytomedicine 14, 396-402]. This study reports the antiulcer and antisecretory gastric acid activities of the plant AE, its BuF and isolated compounds with the possible mechanism involved. Both AE and BuF were assayed on gastric acid secretion of pylorus-ligated mice, on acute models of gastric mucosal lesions, and on rabbit gastric H(+), K(+)-ATPase preparations. Intraduodenal injection of AE or BuF (0.5-2.0g/kg, i.d) produced a dose-related decrease of the basal gastric acid secretion in 4-h pylorus-ligated mice. At 1.0g/kg, BuF decreased the volume (28%) and total acidity (33%) of the basal acid secretion, and reversed the histamine (2.5mg/kg, s.c.)- or bethanecol (1.0mg/kg, s.c.)-induced acid secretion to basal values, indicating inhibition of the gastric proton pump. Pretreatment of mice with the BuF (0.05-0.5g/kg, p.o.) protected against gastric mucosal lesions induced by 75% ethanol, indomethacin (30mg/kg, s.c.) or restraint at 4 degrees C. BuF also decreased the gastric H(+), K(+)-ATPase activity in vitro proportionately to the concentration (IC(50)=58.8microg/ml). The compounds isolated from BuF, consisting mainly of cathechins, procyanidins and flavonoids [Tanae, M.M., Lima-Landman, M.T.R., De Lima, T.C.M., Souccar, C., Lapa, A.J., 2007. Chemical standardization of the aqueous extract of Cecropia glaziovii Sneth endowed with antihypertensive, bronchodilator, antacid secretion and antidepressant-like activities. Phytomedicine 14, 309-313], inhibited the in vitro gastric H(+), K(+)-ATPase activity at equieffective concentrations to that of BuF. The results indicate that C. glazioui constituents inhibit the gastric proton pump; this effect may account for the effective antisecretory and antiulcer activities of the standardized plant extract.

Projections from the anterior interposed nucleus to the red nucleus diminish with age in the mouse.

To analyse the effect of ageing on the projection of the anterior interposed nucleus to the red nucleus, we injected the retrograde tracer fluorogold in the red nucleus of 3-, 6- and 12-month-old mice. The number of labelled neurones in the anterior interposed nucleus fell by 9% between 3 and 6 months and by another 9% between 6 and 12 months (all P < 0.001). This suggests that loss of neurones from the cerebellar nuclei starts well before old age.

ACE activity during the hypotension produced by standardized aqueous extract of Cecropia glaziovii Sneth: a comparative study to captopril effects in rats.

To evaluate the effect of the standardized aqueous extract (AE) of Cecropia glaziovii Sneth on the plasma angiotensin I converting enzyme (ACE-EC 3.4.15.1) activity, rats were treated with a single dose of AE (1 g/kg, p.o.) or repeatedly (0.5 g/kg/bid, p.o.) for 60 days. Captopril (50 mg/kg, p.o.) was used as positive control on the same animals. The effects on the blood pressure were recorded directly from the femoral artery (single dose), or indirectly by the tail cuff method (repeated doses) in conscious rats. The plasma ACE activity was determined spectrofluorimetrically using Hypuril-Hystidine-Leucine as substrate. The arterial blood pressure, heart rate and plasma ACE activity were not significantly modified within 24 h after a single dose administration of AE. Comparatively, blood pressure in captopril treated rats was reduced by 7-16% and heart rate was increased by 10-20% from 30 min to 24 h after drug administration. ACE activity after captopril presented a dual response: an immediate inhibition peaking at 30 min and a slow reversal to 32% up-regulation after 24 h. To correlate the drug effects upon repeated administration of either compound, normotensive rats were separated in three groups: animals with high ACE (48.8+/-2.6 nmol/min/ml), intermediate ACE (39.4+/-1.4 nmol/min/ml) and low ACE (23.5+/-0.6 nmol/min/ml) activity, significantly different among them. Repeated treatment with AE reduced the mean systolic blood pressure (121.7+/-0.5 mm Hg) by 20 mm Hg after 14 days. The hypotension was reversed upon washout 60 days afterwards. Likely, repeated captopril administration decreased blood pressure by 20 mm Hg throughout treatment in all groups. After 30 days treatment with AE (0.5 g/kg/bid, p.o.) the plasma ACE activity was unchanged in any experimental group. After captopril (50 mg/kg/bid, p.o.) administration the plasma ACE activity was inhibited by 50% within 1 h treatment but it was up-regulated by 120% after 12 h in all groups. It is concluded that the hypotension produced by prolonged treatment with AE of C. glaziovii is unrelated to ACE inhibition.