Estudos sôbre a excitação química da córtex cerebral (Ação da acetilcolina)

The author has studied the influence of acetylcholine solutions directly applied on the motor cortex of dogs, cats monkeys and rabbits. For this purpose small squares of filter paper were soaked in the acetylcholine solution and soon afterwards laid on the motor cortex. Solutions varying from 0,2 to 10 per cent have been experimented. It has been shown that local application of the solutions on the motor points, previously localized by induction coil, produced motor reactions. It has been found, in the dogs that 10 per cent acetylcholine solutions cause localized muscular twitchings (clonus) in almost all the animals experimented. Generalised epileptiform convulsions were obtained in44,4% of the dogs. Convulsions were also obtained by employing 1 per cent solution of acetylcholine. Definite response has been obtained with 0,2 per cent solution. Failure of motor action, pointed out by other authors, has been related to the use of anesthetics. Convulsions were easily produced by rapid light mechanical stimulations of the skin covering the muscles in conection with the excited motor point, and the application on the motor point of acetylcholine. The results on monkeys can be summarized as follows. Two species of monkeys were experimented: Cebus capucinus and Macaca mulata. In the monkeys C. capucinus generalised convulsive reactions were induced with actylcholine solutions in a concentration as low as 0,5 per cent. Motor reaction or convulsive seizeres were obtained in seven of the eight monkeys used. Three monkeys M. mulata were stimulated with 10 per cent acetylcholine solution but only localized muscular contraction hae been observed. Similar results has been obtained on the motor cortex of cats and rabbits. One of the three cats employed has shown epileptiform convulsions and the remaining only localized muscular contractions. In the rabbits muscular twitchings have been also induced. The sensitizing power of eserine on the action of acetylcholine has been also searched. The results indicate that a previous application of eserine solution on the motor center, potentiates the action of acetylcholine. The intensity of the muscular twitchings is greater than the obtained before the application of the eserine solution. Generalised epileptiform convulsions sometimes appeared following the use of lower concentrations of acetylcholine than those previously employed. Experiments have been carried out by injecting eserine and prostigmine by parenteral route. A dosis dufficient for induce small muscular tremors did not enhance obviously the motor effects produced by the application of the acetylcholine solutions on the motor cortex. From seven dogs experimented, all previously tested for convulsive seiruzes by application of 1 and 10 per cent acetylcholine solution with negative results, only one has shown epileptiform convulsions after the injection of prostigmine. Morphine has also been tested as facilitating substance for convulsions induced by acetylcholine. Six from the nine dogs submitted to the experiments, developed epileptiform seizures after injection of morphine and stimulation of the motor cortex with acetylcholine. (Table IV). In another series of experiments atropine and nicotine have been studied as for to their action on the motor effects of acetylcholine. Nicotine has a strong convulsant action, even when employed in very high concentration. Since a depressant effect has not appeared even by the applications of high concentrations of nicotine in the motor corteõ of dogs, unlike the classical observations for the autonomus nervous system, it was not possible to verify the action of acetylcholine on a motor center paralised by nicotine. It is important to not that the motor phenomena observed after the first aplication of acetylcholine, can desappear by the renewal of the pieces of filter paper soaked in the acetylcholine solution. Atropine, either applied on the motor point in low concentration, or injected in sufficient amount for inhibiting the “muscarinic effects” of acetylcholine on the autonomous nervous system, did not prevent the motor reactions of acetylcholine on the cerebral cortex.

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.

Impaired glucose homeostasis in mice lacking the alpha1b-adrenergic receptor subtype.

To assess the role of the alpha1b-adrenergic receptor (AR) in glucose homeostasis, we investigated glucose metabolism in knockout mice deficient of this receptor subtype (alpha1b-AR-/-). Mutant mice had normal blood glucose and insulin levels, but elevated leptin concentrations in the fed state. During the transition to fasting, glucose and insulin blood concentrations remained markedly elevated for at least 6 h and returned to control levels after 24 h whereas leptin levels remained high at all times. Hyperinsulinemia in the post-absorptive phase was normalized by atropine or methylatropine indicating an elevated parasympathetic activity on the pancreatic beta cells, which was associated with increased levels of hypothalamic NPY mRNA. Euglycemic clamps at both low and high insulin infusion rates revealed whole body insulin resistance with reduced muscle glycogen synthesis and impaired suppression of endogenous glucose production at the low insulin infusion rate. The liver glycogen stores were 2-fold higher in the fed state in the alpha1b-AR-/- compared with control mice, but were mobilized at the same rate during the fed to fast transition or following glucagon injections. Finally, high fat feeding for one month increased glucose intolerance and body weight in the alpha1b-AR-/-, but not in control mice. Altogether, our results indicate that in the absence of the alpha1b-AR the expression of hypotalamic NPY and the parasympathetic nervous activity are both increased resulting in hyperinsulinemia and insulin resistance as well as favoring obesity and glucose intolerance development during high fat feeding.

Rapidly fatal poisoning with an insecticide containing rotenone.

Introduction: Rotenone is a botanical pesticide derived from extracts of Derris roots, which is traditionally used as piscicide, but also as an industrial insecticide for home gardens. Its mechanism of action is potent inhibition of mitochondrial respiratory chain by uncoupling oxidative phosphorylation by blocking electron transport at complex-I. Despite its classification as mild to moderately toxic to humans (estimated LD50, 300-500 mg/kg), there is a striking variety of acute toxicity of rotenone depending on the formulation (solvents). Human fatalities with rotenone-containing insecticides have been rarely reported, and a rapid deterioration within a few hours of the ingestion has been described previously in one case. Case report: A 49-year-old Tamil man with a history of asthma, ingested 250 mL of an insecticide containing 1.24% of rotenone (3.125 g, 52.1-62.5 mg/kg) in a suicide attempt at home. The product was not labeled as toxic. One hour later, he vomited repeatedly and emergency services were alerted. He was found unconscious with irregular respiration and was intubated. On arrival at the emergency department, he was comatose (GCS 3) with fixed and dilated pupils, and absent corneal reflexes. Physical examination revealed hemodynamic instability with hypotension (55/30 mmHg) and bradycardia (52 bpm). Significant laboratory findings were lactic acidosis (pH 6.97, lactate 17 mmol/L) and hypokalemia (2 mmol/L). Cranial computed tomography (CT) showed early cerebral edema. A single dose of activated charcoal was given. Intravenous hydration, ephedrine, repeated boli of dobutamine, and a perfusor with 90 micrograms/h norepinephine stabilized blood pressure temporarily. Atropine had a minimal effect on heart rate (58 bpm). Intravenous lipid emulsion was considered (log Pow 4.1), but there was a rapid deterioration with refractory hypotension and acute circulatory failure. The patient died 5h after ingestion of the insecticide. No autopsy was performed. Quantitative analysis of serum performed by high-resolution/accurate mass-mass spectrometry and liquid chromatography (LC-HR/AM-MS): 560 ng/mL rotenone. Other substances were excluded by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS/MS). Conclusion: The clinical course was characterized by early severe symptoms and a rapidly fatal evolution, compatible with inhibition of mitochondrial energy supply. Although rotenone is classified as mild to moderately toxic, physicians must be aware that suicidal ingestion of emulsified concentrates may be rapidly fatal. (n=3): stridor, cyanosis, cough (one each). Local swelling after chewing or swallowing soap developed at the earliest after 20 minutes and persisted beyond 24 hours in some cases. Treatment with antihistamines and/or steroids relieved the symptoms in 9 cases. Conclusion: Bar soap ingestion by seniors carries a risk of severe local reactions. Half the patients developed symptoms, predominantly swellings of tongue and/or lips (38%). Cognitive impairment, particularly in the cases of dementia (37%), may increase the risk of unintentional ingestion. Chewing and intraoral retention of soap leads to prolonged contact with the mucosal membranes. Age-associated physiological changes of oral mucosa probably promote the irritant effects of the surfactants. Medical treatment with antihistamines and corticosteroids usually leads to rapid decline of symptoms. Without treatment, there may be a risk of airway obstruction.

Anaesthesia for electroconvulsive therapy: time for a change?

Introduction: Electroconvulsive therapy (ECT) may be used to treat severe depression and needs a specific general anaesthesia. Important cardiovascular changes occur during the ECT with a parasympathetic induced bradycardia followed by a sympathetic response. A dedicated protocol was designed 6 years ago. The goal of this study was to analyse the management of anaesthesia for ECT in our institution, the adherence to the protocol and the occurrence of adverse events during anaesthesia. Methods: After Institutional Ethics Committee approval, we conducted a retrospective analysis of our anaesthesia protocol for patients scheduled for electroshock therapy during a five years period (2004- 2008). The protocol includes administration of atropine subcutaneously 30 minutes before the procedure, followed by general anaesthesia induced with etomidate (0.2 mg/kg). Suxamethonium (1 mg/kg) is administered after the inflation of a pneumatic tourniquet on the opposite arm, in order to observe the electroshocks convulsive effects. The psychiatrist initiates the convulsive crisis once curarisation is achieved. Face mask ventilation is then applied during the post-ictal phase with closed blood pressure monitoring. : 228 ECT were performed in 25 patients. The median dosage of etomidate was 0.37 mg/kg and suxamethonium 1.20 mg/kg. Hypertension during the ECT procedure was present in 62.7% of cases, tachycardia 23.2% and bradycardia 10.5%. Esmolol was administered in 73.4% of hypertensive patients in a range of 0 to 30 mg. The protocol was followed in half of the cases in regards to atropine administration (50.4%). We observed a significant increase of hypertension (73.9%, p = 0.001) after atropine administration, without effect on heart rate. Conclusions: The management of anaesthesia for ECT is specific and follows a predefined protocol in our institution. Adherence to our protocol was poor. Adverse events are frequent and significant association between the administration of atropine and the incidence of hypertension as well as poor protocol adherence implies reconsideration of our anaesthesia protocol for electroconvulsive therapy and better quality control of the clinical practice.

Regulation of gastric and pancreatic lipase secretion by CCK and cholinergic mechanisms in humans.

Gastric lipase (HGL) contributes significantly to fat digestion. However, little is known about its neurohormonal regulation in humans. We studied the role of CCK and cholinergic mechanisms in the postprandial regulation of HGL and pancreatic lipase (HPL) secretion in six healthy subjects. Gastric emptying of a mixed meal and outputs of HGL, pepsin, acid, and HPL were determined with a double-indicator technique. Three experiments were performed in random order: intravenous infusion of 1) placebo, 2) low-dose atropine (5 micrograms.kg-.h-1), and 3) the CCK-A receptor antagonist loxiglumide (22 mumol.kg-.h-1). Atropine decreased postprandial outputs of HGL, pepsin, gastric acid, and HPL (P < 0.03) while slowing gastric emptying (P < 0.05). Loxiglumide markedly increased the secretion of HGL, pepsin, and acid while distinctly reducing HPL outputs and accelerating gastric emptying (P < 0.03). Plasma CCK and gastrin levels increased during loxiglumide infusion (P < 0.03). Atropine enhanced gastrin but not CCK release. Postprandial HGL, pepsin, and acid secretion are under positive cholinergic but negative CCK control, whereas HPL is stimulated by cholinergic and CCK mechanisms. We conclude that CCK and cholinergic mechanisms have an important role in the coordination of HGL and HPL secretion to optimize digestion of dietary lipids in humans.

Magnetic resonance stress tagging in ischemic heart disease.

High-dose dobutamine magnetic resonance stress testing has been shown to be superior to dobutamine stress echocardiography for diagnosis of coronary artery disease (CAD). We determined the feasibility of quantitative myocardial tagging during low- and high-dose dobutamine stress and tested the ability of global systolic and diastolic quantitative parameters to identify patients with significant CAD. Twenty-five patients suspected of having significant CAD were examined with a standard high-dose dobutamine/atropine stress magnetic resonance protocol (1.5-T scanner, Philips). All patients underwent invasive coronary angiography as the standard of reference for the presence (n = 13) or absence (n = 12) of significant CAD. During low-dose dobutamine stress, systolic (circumferential shortening, systolic rotation, and systolic rotation velocity) and diastolic (velocity of circumferential lengthening and diastolic rotation velocity) parameters changed significantly in patients without CAD (all P < 0.05 vs. rest) but not in patients with CAD. Identification of patients without and with CAD during low-dose stress was possible using the diastolic parameter of "time to peak untwist." At high-dose stress, none of the global systolic or diastolic parameters showed the potential to identify the presence of significant CAD. With myocardial tagging, a quantitative analysis of systolic and diastolic function was feasible during low- and high-dose dobutamine stress. In our study, the diastolic parameter of time to peak untwist as assessed during low-dose dobutamine stress was the most promising global parameter for identification of patients with significant CAD. Thus quantitative myocardial tagging may become a tool that reduces the need for high-dose dobutamine stress.

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Acute organophosphate (OP) intoxication is associated with many symptoms and clinical signs, including potentially life-threatening seizures and status epilepticus. Instead of being linked to the direct cholinergic toxidrome, OP-related seizures are more probably linked to the interaction of OPs with acetylcholineindependent neuromodulation pathways, such as GABA and NMDA. The importance of preventing, or recognizing and treating OP-related seizures lies in that, the central nervous system (CNS) damage from OP poisoning is thought to be due to the excitotoxicity of the seizure activity itself rather than a direct toxic effect. Muscular weakness and paralysis occurring 1-4 days after the resolution of an acute cholinergic toxidrome, the intermediate syndrome is usually not diagnosed until significant respiratory insufficiency has occurred; it is nevertheless a major cause of OP-induced morbidity and mortality and requires aggressive supportive treatment. The condition usually resolves spontaneously in 1-2 weeks.Treatment of OP intoxication relies on prompt diagnosis, and specific and immediate treatment of the lifethreatening symptoms. Since patients suffering from OP poisoning can secondarily expose care providers via contaminated skin, clothing, hair, or body fluids. EMS and hospital caregivers should be prepared to protect themselves with appropriate protective equipment, isolate such patients, and decontaminate them. After prompt decontamination, the initial priority of patient management is an immediate ABCDE (A : airway, B : breathing, C : circulation, D : dysfunction or disability of the central nervous system, and E : exposure) resuscitation approach, including aggressive respiratory support, since respiratory failure is the usual ultimate cause of death. The subsequent priority is initiating atropine therapy to oppose the muscarinic symptoms and diazepam to prevent or control seizures, with oximes added to enhance acetylcholinesterase (AChE) activity recovery. Large doses of atropine and oximes may be necessary for poisoning due to suicidal ingestions of OP pesticides.

Effects of adrenergic and cholinergic blockade on insulin-induced stimulation of calf blood flow in humans.

Euglycemic hyperinsulinemia stimulates both sympathetic nerve activity and blood flow to skeletal muscle, but the mechanism is unknown. Possible mechanisms that may stimulate muscle blood flow include neural, humoral, or metabolic effects of insulin. To determine whether such insulin-induced vasodilation is modulated by stimulation of adrenergic or cholinergic mechanisms, we obtained, in eight healthy lean subjects, plethysmographic measurements of calf blood flow during 3 h of hyperinsulinemic (1 mU.kg-1.min-1) euglycemic clamp performed alone or during concomitant beta-adrenergic (propranolol infusion), cholinergic (atropine infusion), or alpha-adrenergic (prazosin administration) blockade. Euglycemic hyperinsulinemia alone increased calf blood flow by 38 +/- 10% (means +/- SE) and decreased vascular resistance by 27 +/- 4% (P < 0.01). The principal new observation is that these insulin-induced vasodilatory responses were not attenuated by concomitant propranolol or atropine infusion, nor were they potentiated by prazosin administration. In conclusion, these findings provide evidence that during euglycemic hyperinsulinemia in lean healthy humans stimulation of muscle blood flow is not mediated primarily by beta-adrenergic or cholinergic mechanisms. Furthermore, alpha-adrenergic mechanisms do not markedly limit insulin-induced stimulation of muscle blood flow.

Interaction of alpha-melanotropin with central dopamine systems: role of hormonal state and molecular structure

The tubero-infundibular and nigrostriatal DA neurone systems of rats respond to systemic (i.p.) injection of alpha-MSH (2-100 microgram/kg). The response of the tubero-infundibular (arcuate) DA neurones, an increase in cellular fluorescence intensity which can be interpreted as a sign of increased neuronal activity, is essentially the same in males, estrogen-progesterone-pretreated ovariectomized females and hypophysectomized males, whereas the type of response elicited by alpha-MSH in the nigral DA neurones depends upon the hormonal state of the animal. Differences between the two DA neurone groups exist also with regard to the effects of peptide fragments containing the two active sites of the alpha-MSH molecule. Results of lesion experiments in the lower brainstem (area postrema) and of blockade of muscarinic mechanisms by atropine further point to differences in the mechanisms underlying the peptide effects on the two neurone systems. The reaction of the tubero-infundibular DA system (which controls the pars intermedia of the pituitary) can be considered to reflect the activation of a feedback mechanism on MSH secretion, while the functional counterpart of the changes observed in the nigral system remains unknown at the present time.

EZ-IO(®) intraosseous device implementation in a pre-hospital emergency service: A prospective study and review of the literature.

INTRODUCTION: Intraosseous access is increasingly recognised as an effective alternative vascular access to peripheral venous access. We aimed to prospectively study the patients receiving prehospital intraosseous access with the EZ-IO(®), and to compare our results with those of the available literature. METHODS: Every patient who required an intraosseous access with the EZ-IO from January 1st, 2009 to December 31st, 2011 was included. The main data collected were: age, sex, indication for intraosseous access, localisation of insertion, success rate, drugs and fluids administered, and complications. All published studies concerning the EZ-IO device were systematically searched and reviewed for comparison. RESULTS: Fifty-eight patients representing 60 EZ-IO procedures were included. Mean age was 47 years (range 0.5-91), and the success rate was 90%. The main indications were cardiorespiratory arrest (74%), major trauma (12%), and shock (5%). The anterior tibia was the main route. The main drugs administered were adrenaline (epinephrine), atropine and amiodarone. No complications were reported. We identified 30 heterogeneous studies representing 1603 EZ-IO insertions. The patients' characteristics and success rate were similar to our study. Complications were reported in 13 cases (1.3%). CONCLUSION: The EZ-IO provides an effective way to achieve vascular access in the pre-hospital setting. Our results were similar to the cumulative results of all studies involving the use of the EZ-IO, and that can be used for comparison for further studies.

L'agitation postopératoire en salle de réveil

L'agitation postopératoire chez les patients adultes dans les premières heures après le réveil¦est un domaine peu étudié. Nous avons effectué des recherches pour trouver des études¦concernant l'agitation postopératoire sur Pubmed pour les 10 dernières années. Les termes de¦recherche étaient agitation, emergence delirium, facteurs de risques (anglais : risk factors),¦agitation treatment, Riker scale. Ceci n'a permis de trouver que 2 études à propos de ce sujet.¦Pourtant, elle concerne environ 5% (1) (2) des patients adultes opérés, ce qui n'est pas¦négligeable.¦En effet, elle peut avoir de sérieuses conséquences en terme de lésions des patients¦(arrachement de cathéter, de tube d'intubation) ou du personnel soignant, ainsi qu'en terme de¦coûts occasionnés par les différentes complications.¦Selon l'étude de Lepousé (1) et l'étude de Radtke (2), certains facteurs seraient déterminants¦dans la survenue de l'agitation postopératoire, dont quelques-uns sont évitables.¦Dans l'étude observationnelle prospective de Radtke (2), il a déjà été démontré que l'âge était¦en lien avec l'agitation postopératoire. Les tranches d'âge les plus à risque sont : les moins de¦40 ans (18-39 ans) (OR=2.1, CI=1.1-3.8, p=0.02) et les plus de 64 ans (OR=2.1, CI=1.1-3.4,¦p=0.02). Les études de Lepousé (1) et de Radtke (2) ont montré que la prémédication par¦benzodiazépines pourrait aussi être un facteur de risque (Lepousé (1): CI=1.1-3.3, p=0.02)¦(Radtke (2): OR=2.4, CI=1.0-5.6, p≤0.05). L'intensité de la douleur est également liée à la¦survenue d'une agitation postopératoire (OR=1.8, CI=1.0-3.0, p<0.04) (2). D'autres facteurs¦comme certains médicaments utilisés lors de l'anesthésie (l'étomidate) (2), le type de¦chirurgie [abdominale (1) (2), musculosquelettique (2), de la tête et du cou(2), de la¦poitrine(1)] seraient en lien avec la survenue d'une agitation postopératoire.¦4¦Il restait toutefois beaucoup de facteurs dont la relation avec l'agitation postopératoire n'avait¦pas été évaluée ou dont l'étude n'a pas eu de résultat significatif [par exemple, les¦benzodiazépines à long terme (1), ou l'anesthésie locorégionale(2)].¦Le but de cette étude était premièrement de déterminer si la fréquence de l'agitation¦postopératoire dans la population prise en compte ici est comparable à celle observée dans les¦études de Radtke et de Lepousé.¦Ensuite il s'agissait d'identifier, lors d'agitation postopératoire chez des patients adultes,¦parmi certains facteurs possibles, ceux pouvant être en lien avec l'agitation postopératoire, et¦s'ils étaient similaires à ceux retrouvés dans les études déjà publiées.¦Les comorbidités sont un de ces facteurs. La dose de benzodiazépines dans les 24 heures¦précédent l'intervention, ainsi que les benzodiazépines en médication chronique, par un effet¦paradoxal, pourraient être en lien avec un état d'agitation. Dans le même ordre d'idée, nous¦avons comparé le type d'anesthésie utilisé, locorégionale versus générale ou combinée, avec¦la survenue de cet état. Nous nous sommes aussi penchés sur la dose intraopératoire totale¦d'opioïdes et l'administration intraopératoire d'atropine, médicaments largement utilisés lors¦des interventions, et qui seraient des facteurs modifiables si une relation avec l'agitation était¦démontrée. Enfin, l'hypotension intraopératoire provoquant une hypoperfusion cérébrale¦relative pourrait être liée à la survenue d'une agitation postopératoire.¦Nous avons également observé d'autres variables, comme l'intensité de la douleur, déjà¦démontrée comme étant en rapport avec l'agitation postopératoire, et l'hypoxie¦intraopératoire, qui pourrait favoriser une hypoxie cérébrale, et par là une agitation.¦Enfin, nous avons cherché s'il existe un lien entre la survenue d'une agitation postopératoire¦et d'un état confusionnel postopératoire, c'est-à-dire se développant dans la semaine suivant¦l'opération, une question qui n'avait pas encore été étudiée.

Undifferentiated and differentiated PC12 cells protected by huprines against injury induced by hydrogen peroxide

Oxidative stress is implicated in the pathogenesis of neurodegenerative disorders and hydrogen peroxide (H2O2) plays a central role in the stress. Huprines, a group of potent acetylcholinesterase inhibitors (AChEIs), have shown a broad cholinergic pharmacological profile. Recently, it has been observed that huprine X (HX) improves cognition in non transgenic middle aged mice and shows a neuroprotective activity (increased synaptophysin expression) in 3xTg-AD mice. Consequently, in the present experiments the potential neuroprotective effect of huprines (HX, HY, HZ) has been analyzed in two different in vitro conditions: undifferentiated and NGF-differentiated PC12 cells. Cells were subjected to oxidative insult (H2O2, 200 µM) and the protective effects of HX, HY and HZ (0.01 µM- 1 µM) were analyzed after a pre-incubation period of 24 and 48 hours. All huprines showed protective effects in both undifferentiated and NGF-differentiated cells, however only in differentiated cells the effect was dependent on cholinergic receptors as atropine (muscarinic antagonist, 0.1 µM) and mecamylamine (nicotinic antagonist, 100 µM) reverted the neuroprotection action of huprines. The decrease in SOD activity observed after oxidative insult was overcome in the presence of huprines and this effect was not mediated by muscarinic or nicotinic receptors. In conclusion, huprines displayed neuroprotective properties as previously observed in in vivo studies. In addition, these effects were mediated by cholinergic receptors only in differentiated cells. However, a non-cholinergic mechanism, probably through an increase in SOD activity, seems to be also involved in the neuroprotective effects of huprines.

Retrospective study on clinical management of indolent ulcers in Boxer dogs

Indolent ulcers are superficial corneal ulcers secondary to several changes on the corneal surface. They are frequently observed in middle-aged Boxer dogs, cause pain of acute onset and requires appropriate treatment. Aiming to evaluate the efficacy of clinical managements on the rate of healing of indolent ulcers, a retrospective study was conducted (1997-2008). Results demonstrated that proteinase inhibitors were the most often prescribed medication, and its administration did not interfere on the healing rate, as well as observed in dogs that received 1% atropine, antibiotics and anti-inflammatory drugs. Healing was delayed in dogs administered orally with vitamin C, but the healing process was faster on those dogs that went through corneal debridement/cauterization. In conclusion, to know the various types of treatments seems to be fundamental for the rapid resolution of the disease. It is suggested that debridement/cauterization, administration of proteinase inhibitor eye drops, prophylactic topical antibiotics and oral vitamin C, should be considered as an effective clinical management for indolent ulcers in Boxer dogs.

Characterization of nerve-induced relaxation of gastrointestinal sphincteric smooth muscle in a South American opossum (Didelphis albiventris)

The presence of inhibitory nonadrenergic noncholinergic (NANC) intrinsic innervation of the circular muscle of the gastrointestinal sphincters of the South American (SA) opossum was investigated in vitro. Isolated circular muscle strips from the esophagogastric and ileocolonic junctions but not from the gastroduodenal (pylorus) region developed spontaneous tension. Tetrodotoxin (TTX, 1 µM) augmented the spontaneous tension only in the ileocolonic junction strips. Electrical field stimulation of esophagogastric and ileocolonic junction strips caused frequency-dependent responses consisting of a relaxation at lower frequencies (<1 Hz) and a biphasic response or contraction at higher frequencies. In the strips from the pyloric region electrical field stimulation abolished the spontaneous activity at lower frequencies and induced contractions at higher frequencies. The responses elicited by electrical field stimulation in the three sphincters were abolished by TTX (1 µM). Electrical field-induced contractions were reduced while relaxations were enhanced by atropine (1 µM). In the presence of atropine (1 µM) and guanethidine (3 µM), electrical field stimulation, nicotine and ATP induced frequency- or concentration-dependent relaxations of the three sphincters that were abolished by TTX (1 µM). Isoproterenol and sodium nitroprusside caused concentration-dependent relaxations which were TTX-resistant. These findings indicate that the sphincteric circular muscle of the SA opossum gastrointestinal tract is relaxed by the activation of intrinsic NANC nerves and therefore can be used as a model for the study of the mechanisms involved in these responses