Glabridin alleviates ischemia/reperfusion-induced functional failure of smooth muscle of rat ileum by upregulating the cAMP / Glabridin alivia la falla funcional inducida por isquemia/reperfusión del músculo liso de ileum murino regulando el incremento de cAMP

Despite the development of modern medicine, alternative medicine, which has not lost its timeliness, remains attractive for the treatment of various diseases. Glabridin, a major flavonoid of Glycyrrhiza glabra, is known for its antioxidant and anti-inflammatory activity. The aim of this study was: 1) to determine the possible protective role of glabridin against ischemia/reperfusion (I/R) injury of the intestine; 2) to evaluate the in vitrocontractile responses of ileum smooth muscles to acetylcholine after an intestinal I/R; and 3) to explain the underlying molecular mechanism of its effect. Rats were assigned to groups of six rats each; 1) I/R, 2) gla10, 3) gla20, 4) gla40, 5) N5-[imino(nitroamino)methyl]-L-ornithine, methyl ester monohydrochloride (L-NAME)+gla40, and 6) Sham group. The healing effect of glabridin was abolished by L-NAME. Glabridin did not cause contractility of the smooth muscles to acetylcholine-induced contractile responses in intestinal I/R. Yet, it increased to spontaneous basal activity.

A pesar del desarrollo de la medicina moderna, la medicina alternativa, sin perder su vigencia, sigue siendo atractiva para el tratamiento de varias enfermedades. Glabradina, el flavonoide mayoritario de Glycyrrhiza glabra, es conocido por su actividad antioxidante y antiinflamatoria. Los propósitos de este estudio fueron: 1) Determinar el posible rol protector de glabradina ante daños intestinales por isquemia/reperfusion (I/R) 2) Evaluar in vitrolas respuestas de contracción de los músculos lisos del ileum ante acetilcolina después de I/R intestinal; y 3) Explicar el mecanismo molecular subyacente de este efecto. Se asignaron grupos de seis ratas: 1) I/R, 2) gla10, 3) gla20, 4) gla40, 5) N5-[imino(nitroamino)metil]-L-ornithina, metil ester monohidrochloruro (L-NAME)+gla40, y 6) Grupo testigo. El efecto curativo de glabridina fue abolido por L-NAME. Glabridina no causó contracción en el músculo liso como respuesta acetilcolina-inducida I/R. Además, incrementa la actividad basal expontánea.

Role of adenylyl cyclase in reduced ß-adrenoceptor-mediated vasorelaxation during maturation

Beta-adrenergic receptor (βAR)-dependent blood vessel relaxation is impaired in older animals and G protein activation has been suggested as the causative mechanism. Here, we investigated the role of βAR subtypes (β1AR, β2AR, and β3AR) and cAMP in maturation-dependent vasorelaxation impairment. Aortic rings from 15 Sprague-Dawley male rats (3 or 9 weeks old) were harvested and left intact or denuded of the endothelium. Vascular relaxation in aortic rings from younger and older groups was compared in the presence of βAR subtype agonists and antagonists along with cAMP and cGMP antagonists. Isolated aortic rings were used to evaluate relaxation responses, protein expression was evaluated by western blot or real time PCR, and metabolites were measured by ELISA. Expression of βAR subtypes and adenylyl cyclase was assessed, and cAMP activity was measured in vascular tissue from both groups. Isoproterenol- and BRL744-dependent relaxation in aortic rings with and without endothelium from 9-week-old rats was impaired compared with younger rats. The β1AR antagonist CGP20712A (10-7 M) did not affect isoproterenol or BRL744-dependent relaxation in arteries from either group. The β2AR antagonist ICI-118,551 (10-7 M) inhibited isoproterenol-dependent aortic relaxation in both groups. The β3AR antagonist SR59230A (10-7 M) inhibited isoproterenol- and BRL744-dependent aortic ring relaxation in younger but not in older rats. All βAR subtypes were expressed in both groups, although β3AR expression was lower in the older group. Adenylyl cyclase (SQ 22536) or protein kinase A (H89) inhibitors prevented isoproterenol-induced relaxation in younger but not in older rats. Production of cAMP was reduced in the older group. Adenylyl cyclase III and RyR3 protein expression was higher in the younger group. In conclusion, altered expression of β3AR and adenylyl cyclase III may be responsible for reduced cAMP production in the older group.

Secretin induces neurite outgrowth of PC12 through cAMP-mitogen-activated protein kinase pathway

The gastrointestinal functions of secretin have been fairly well established. However, its function and mode of action within the nervous system remain largely unclear. To gain insight into this area, we have attempted to determine the effects of secretin on neuronal differentiation. Here, we report that secretin induces the generation of neurite outgrowth in pheochromocytoma PC12 cells. The expressions of Tau and beta-tubulin, neuronal differentiation markers, are increased upon secretin stimulation. In addition, secretin induces sustained mitogen-activated protein kinase (MAPK) activation and also stimulates the cAMP secretion. Moreover, the neurite outgrowth elicited by secretin is suppressed to a marked degree in the presence of either PD98059, a specific MAPK/ERK kinase (MEK) inhibitor, or H89, a specific protein kinase A (PKA) inhibitor. Taken together, these observations demonstrate that secretin induces neurite outgrowth of PC12 cells through cAMP-MAPK pathway, and provide a novel insight into the manner in which secretin participates in neuritogenesis.

Comparaçäo entre diferentes métodos para avaliar a presença de auto-anticorpos dirigidos ao receptor de TSH em pacientes com moléstia de Graves-Basedow / Comparison between different methods for evaluate the presence of autoantibodies against TSH receptor in patients with Graves-Basedow'disease

Auto-anticorpos anti-receptores de TSH (TSHRAbs) foram avaliados por dois diferentes métodos [TRAb, como porcentagem de inibiçäo de ligaçäo do TSH por anticorpos séricos e produçäo de AMP cíclico em cultura de células CHO expressando o receptor de TSH humano recombinante (CHO-rhT-SHR)] em 52 pacientes (36F/16M) com moléstia de Graves-Basedow (DGB), tanto antes do tratamento como aos 6 e 12 meses de terapia contínua com metimazol (40-60mg/dia) e L-tiroxina (100pg/dia); outros 20 pacientes tireotóxicos (12F/8M) foram tratados com doses individualizadas de radioiodo. Os TSHRAbs determinados pelo radioreceptorensaio foram positivos em 47/52 pacientes (90,4 por cento) com valor médioñEPM de 56,7ñ3,9 por cento, diminuindo significantemente aos 6 (40,5ñ3,2 por cento) e 12 meses (43,5ñ4,7 por cento) de terapêutica, bem como após radioiodo (30,7ñ4,5 por cento). Os TSHRAbs foram discriminados pelo bioensaio em todos os 52 pacientes com DGB ativa (1122ñ409 por cento). Após 6 e 12 meses de terapêutica houve decréscimo (näo significante) dos valores iniciais. Nenhum indivíduo do grupo controle normal (n= 80) apresentou TSHRAbs detectado por qualquer dos métodos. Portanto, a sensibilidade da pesquisa dos anticorpos pelo bioensaio, nos 52 pacientes com DGB ativa, foi maior que nos mesmos indivíduos avaliados pelo radioreceptorensaio. Houve correlaçäo positiva (r= 0,59; p<0,001) entre TRAb e CHO-rhTSHR. Concluímos que a pesquisa dos TSHRAbs, realizada quer pelo radioreceptorensaio como pelo bioensaio, constitui recurso útil para se avaliar a atividade autoimune na DGB.

Effect of policosanol on cerebral ischemia in Mongolian gerbils

Policosanol is a mixture of higher aliphatic primary alcohols isolated from sugar cane wax, whose main component is octacosanol. An inhibitory effect of policosanol on platelet aggregation and cerebral ischemia in animal models has been reported. Thus, the objective of the present study was to evaluate the effect of policosanol on cerebral ischemia induced by unilateral carotid ligation and bilateral clamping and recirculation in Mongolian gerbils. Policosanol (200 mg/kg) administered immediately after unilateral carotid ligation and at 12- or 24-h intervals for 48 h significantly inhibited mortality and clinical symptoms when compared with controls, whereas lower doses (100 mg/kg) were not effective. Control animals showed swelling (tissue vacuolization) and necrosis of neurons in all areas of the brain studied (frontal cortex, hippocampus, striatum and olfactory tubercle), showing a similar injury profile. In the group treated with 200 mg/kg policosanol swelling and necrosis were significantly reduced when compared with the control group. In another experimental model, comparison between groups showed that the brain water content of control gerbils (N = 15) was significantly higher after 15 min of clamping and 4 h of recirculation than in sham-operated animals (N = 13), whereas policosanol (200 mg/kg) (N = 19) significantly reduced the edema compared with the control group, with a cerebral water content identical to that of the sham-operated animals. cAMP levels in the brain of control-ligated Mongolian gerbils (N = 8) were significantly lower than those of sham-operated animals (N = 10). The policosanol-treated group (N = 10) showed significantly higher cAMP levels (2.68 pmol/g of tissue) than the positive control (1.91 pmol/g of tissue) and similar to those of non-ligated gerbils (2.97 pmol/g of tissue). In conclusion, our results show an anti-ischemic effect of policosanol administered after induction of cerebral ischemia, in two different experimental models in Mongolian gerbils, suggesting a possible therapeutic effect in cerebral vascular disorders

Enterotoxigenicidad de campylobacter jejuni subsp. jejuni y su relación con aumento de AMPc y alteración electrolítica en el intestino de ratas / The relationship of campylobacter jejuni subsp. jejuni enterotoxigenicity and the increase of cAMP and electrolytic alterations in the rat intestine

Background: Small intestine alterations produced by the enterotoxigenic capacity of Campylobacter jejuni subsp. jejuni are similar to the hydric, electrolytic and pathological changes caused by choleraic and thermolabile Escherichia coli toxins. Aim: To study the enterotoxigenic capacity of 4 strains of Campylobacter jejuni subsp. jejuni using the intestinal loop model. Material and methods: Rat intestinal loops were inoculated with culture filtrates of the four strains. Enterotoxigenicity was assessed by fluid accumulation, the increase in Na+ and Cl- in the loop fluid, and cAMP increases in loop tissues. An enterotoxigenic Escherichia coil strain and sterile Brucella both were used as positive and negative controls, respectively. Results: The filtrates of two strains produced fluid accumulation in the loops, significantly increased Na+ and Cl - secretion to the intestinal lumen and increased tissue cAMP levels. Conclusions: Some strains of Campylobacter jejuni subsp. jejuni are able to show enterotoxigenicity in vivo, increasing cAMP levels in the intestinal cells and altering electrolyte exchange mechanisms

Agents that affect cAMP levels or protein kinase A activity modulate memory consolidation when injected into rat hippocampus but not amygdala

Male Wistar rats were trained in one-trial step-down inhibitory avoidance using a 0.4-mA footshock. At various times after training (0, 1.5, 3,6 and 9 h for the animals implanted into the CA1 region of the hippocampus; 0 and 3 h for those implanted into the amygdala), these animals received microinfusions of SKF38393 (7.5 mug/side), SCH23390 (0.5 mug/side), norepinephrine (0.3 mug/side), timolol (0.3 mug/side), 8-OH-DPAT (2.5 mug/side), NAN-190 (2.5 mug/side), forskolin (0.5 mug/side), KT5720 (0.5 mug/side) or 8-Br-cAMP (1.25 mug/side). Rats were tested for retention 24 h after training. When given into the hippocampus 0 h post-training, norepinephrine enhanced memory whereas KT5720 was amnestic. When given 1.5 h after training, all treatments were ineffective. When given 3 or 6 h post-training, 8-Br-cAMP, forskolin, SKF38393, norepinephrine and NAN-190 caused memory facilitation, while KT5720, SCH23390, timolol and 8-OH-DPAT caused retrograde amnesia. Again, at 9 h after training, all treatments were inffective. When given into the amygdala, norepinephrine caused retrograde facilitation at 0 h after training. The other drugs infused into the amygdala did not cause any significant effect. These data suggest that in the hippocampus, but not in the amygdala, a cAMP/protein kinase A pathway is involved in memory cosolidation at 3 and 6 h after training, which is regulated by D1, Beta, and 5HT1A receptors. This correlates with data on increased post-training cAMP levels and a dual peak of protein kinase A activity and CREB-P levels (at 0 and 3-6 h) in rat hippocampus after training in this task. These results suggest that the hippocampus, but not the amygdala, is involved in long-term storage of step-down inhibitory avoidance in the rat.

"In vivo" and "in vitro" antitumoral action of Larrea divaricata cav

We previously reported that aqueous extract of Larrea divaricata Cav had an antiproliferative activity upon tumoral lymphoid cells (BW 5147), without affecting normal immunity. To determine the probable mechanism of the inhibitory action of the extract upon cell growth, the participation of intracellular signals involved in the inhibition of cell proliferation, namely the activation of adenylate cyclase system was studied. The production of cyclic 3', 5 adenosine monophosphate (cAMP) in presence and absence of extract was analized. The extract increased the cAMP levels, but neither the cAMP production nor the inhibitory effect of the extract on proliferation were blocked by a beta adrenergic receptor antagonist (propranolol) or by histaminergic receptor antagonistis (cimetidine and mepyramine). So, we concluted that the antiproliferative activity of the extract of BW 5147 cells would be mediated by an increase in cAMP intracellular levels no related to the activation of the membrane receptors here studied. In parallel, the extract was administered to a pregnant rat with a spontaneous mammarian carcinoma and "in vivo"antitumoral activity was found.

Effects of calcium antagonists on contractions of chorionic arteries in normal and preeclampsia placenta

This study was undertaken to observe the effects of organic or inorganic calcium antagonists and to investigate the involvement of cyclic nucleotides in regulating the vascular tone in the chorionic artery from normal or preeclamptic placenta. KCI and prostaglandin (PG) F2 alpha produced marked and constant contractions in chorionic arterial preparations of both normal and preeclamptic placentas. Nifedipine (NIF), verapamil (VER) and diltiazem (DIL) reduced the tension that had been produced by KCI and PGF2 alpha in a concentration-dependent fashion in both preparations, and the potency order of the three agents was NIF> VER > DIL. In preeclamptic arteries, however, the magnitudes of vasodilatation induced by NIF and DIL were much smaller than those in normal chorionic arteries. Mg2+ and Cd2+ also relaxed the tension induced by KCI and PGF2 alpha. In preeclamptic chorionic artery, the vasodilatation induced by Mg2+ was significantly potentiated, while that by Cd2+ was not. Removing endothelium did not alter cyclic GMP content in both preparations. In both preparations contracted by PGF2 alpha, nitroprusside markedly increased cyclic GMP content, but neither cyclic GMP nor cyclic AMP content was affected by acetylcholine, NIF, isopro-terenol, or Mg2+. The above results suggest that neither cyclic AMP nor cyclic GMP is involved in regulating the vascular tone of chorionic artery and that sensitivity of the artery in preeclampsia to the inhibitory action of calcium antagonist might be different from that in normal placenta.

Evaluation of cyclic adenosine monophosphate [cAMP] and nuclear estrogen receptor [ERn] in mammary tumors of female rats after irradiation and hormonal therapy

This study was designed to investigate the effect of hormonal treatment and irradiation on the level of cAMP and ERn in DMBA induced mammary gland carcinoma tissue of female rats. The results showed that tamoxifen has a better advantage in treatment of DMBA-induced mammary gland tumour of female rats than DES. The anti-regression of ERn level cAMP level in verapamil group explores the role of cAMP and calcium ion on the mechanism of ERn. The results with different single doses of gamma radiation revealed the positive relation between the cAMP values and the amount of single radiation dose but this relation is absent with ERn value

In vitro capacitation of goat spermatozoa.

Goat epididymal and ejaculated spermatozoa were incubated in Krebs-Ringer bicarbonate buffer containing pyruvate and lactate as energy source. A 3 hr incubation for epididymal and 4 hr for ejaculated spermatozoa was required for the capacitation and acrosome reaction to take place. Calcium is an essential requirement which was needed for motility maintenance/activation and for the initiation of acrosome reaction. A 2-fold increase in cAMP content was measured over 3 hr period of incubation of goat epididymal spermatozoa which was not seen when calcium ions were either omitted or chelated with EGTA. There is thus a definite involvement of Ca2+ ions and cAMP in capacitation and acrosome reaction of goat spermatozoa.

Blockade by burimamide of the effects of clonidine on cardiac contractility phosphorylase activation and cyclic adenosine monophosphate in isolated guinea pig heart.

Clonidine in a dose-range of 2.5 microgram to 80 microgram caused positive inotropic effect, which was accompanied by increase in the cyclic AMP levels and phosphorylase-activation of the isolated perfused guinea pig heart. Clonidine-induced biochemical and mechanical effects were blocked by burimamide, an H2-receptor antagonist Propranolol (1 x 10(-6)M), phentolamine (1 x 10(-6)M) or reserpine pretreatment, did not affect the clonidine responses on the perfused guinea pig heart. Clonidine reduced the 4-methyl-histamine (H2-agonist) responses of guinea pig heart. Our data suggest that the cardiac effects of clonidine may be due to stimulation of H2-type of receptors.