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Introduction and aims: Cirrhosis is the common outcome of liver diseases. It can be decompensated and lead to the development of complications, such as encephalopathy. Hyperammonemia that develops due to liver dysfunction is etiopathologically related to hepatic encephalopathy. Caffeine increases the activity of the urea cycle in the liver, augmenting ammonia degradation. By antagonizing adenosine receptors, it also has a hepatoprotective effect, impeding the formation of fibrosis, as well as having a stimulating effect on the central nervous system. The present study analyzed the effects of caffeine on the progression of cholestatic liver fibrosis and hepatic encephalopathy. Materials and methods: An experimental model of cholestatic liver fibrosis, through common bile duct ligature, and of hepatic encephalopathy, through the administration of a high-protein diet, was constructed. Male Wistar rats (n = 32) were equally divided into 4 groups. The experiment lasted 28 days, with the administration of 50 mg/kg/day of caffeine. Laboratory tests, histologic analyses of the liver and encephalon, open field tests (OFTs), and daily behavioral analyses were carried out. Results: The ligated animals treated with caffeine had lower mean transaminase levels and improved histologic aspects of the liver and encephalon. The untreated ligated animals were clearly lethargic and apathetic at the last week of the experiment, confirmed by reduced exploratory activity during the OFT. Conclusion: Caffeine improved the microarchitecture of the liver and encephalon of the cirrhotic animals and prevented the decrease in exploratory behavior of the animals during the OFT. Resumen: Introducción y objetivos: La cirrosis es el desenlace común de las enfermedades hepáticas. Puede ser descompensada y llevar al desarrollo de complicaciones como la encefalopatía. La hiperamonemia que se desarrolla debido a la disfunción hepática está etiopatológicamente relacionada con la encefalopatía hepática. La cafeína (CAF) aumenta la actividad del ciclo de la urea en el hígado, aumentando la degradación del amonio. Además, al antagonizar receptores de adenosina, ejerce un efecto hepatoprotector, impidiendo la formación de fibrosis y tiene un efecto estimulante en el sistema nervioso central. El objetivo del presente estudio fue el análisis de los efectos de la cafeína sobre la evolución de la fibrosis hepática colestásica y de la encefalopatía hepática. Material y métodos: Se construyó un modelo experimental de fibrosis hepática colestásica, por medio de la ligadura del conducto biliar común, y de encefalopatía hepática, con la administración de una dieta hiperprotéica. Treinta y dos ratas Wistar machos fueron divididas igualmente en 4 grupos. El experimento duró 28 días, con administración de CAF 50 mg/kg/día. Se realizaron pruebas de laboratorio, análisis histológicos de hígado y encéfalo, pruebas de campo abierto (PCA) y análisis conductuales diarios. Resultados: Los animales ligados tratados con CAF presentaron menores medias de transaminasas y mejorías histológicas en hígado y encéfalo. El grupo ligado sin tratamiento se presentó claramente letárgico y apático en la última semana de experimento, lo cual fue comprobado por la disminución de la actividad exploratoria durante la PCA. Conclusión: La CAF mejoró la microarquitectura hepática y encefálica de los animales cirróticos. Además, impidió la disminución de la actividad exploratoria de los animales durante la PCA.

Resumen: Introducción y objetivos: La cirrosis es el desenlace común de las enfermedades hepáticas. Puede ser descompensada y llevar al desarrollo de complicaciones como la encefalopatía. La hiperamonemia que se desarrolla debido a la disfunción hepática está etiopatológicamente relacionada con la encefalopatía hepática. La cafeína (CAF) aumenta la actividad del ciclo de la urea en el hígado, aumentando la degradación del amonio. Además, al antagonizar receptores de adenosina, ejerce un efecto hepatoprotector, impidiendo la formación de fibrosis y tiene un efecto estimulante en el sistema nervioso central. El objetivo del presente estudio fue el análisis de los efectos de la cafeína sobre la evolución de la fibrosis hepática colestásica y de la encefalopatía hepática. Material y métodos: Se construyó un modelo experimental de fibrosis hepática colestásica, por medio de la ligadura del conducto biliar común, y de encefalopatía hepática, con la administración de una dieta hiperproteica. Treinta y dos ratas Wistar machos fueron divididas igualmente en cuatro grupos. El experimento duró 28 días, con administración de CAF 50 mg/kg/d. Se realizaron pruebas de laboratorio, análisis histológicos de hígado y encéfalo, pruebas de campo abierto (PCA) y análisis conductuales diarios. Resultados: Los animales ligados tratados con CAF presentaron menores medias de transaminasas y mejorías histológicas en hígado y encéfalo. El grupo ligado sin tratamiento se presentó claramente letárgico y apático en la última semana de experimento, lo cual fue comprobado por la disminución de la actividad exploratoria durante la PCA. Conclusión: La CAF mejoró la microarquitectura hepática y encefálica de los animales cirróticos. Además, impidió la disminución de la actividad exploratoria de los animales durante la PCA. Abstract: Introduction and aims: Cirrhosis is the common outcome of liver diseases. It can be decompensated and lead to the development of complications, such as encephalopathy. Hyperammonemia that develops due to liver dysfunction is etiopathologically related to hepatic encephalopathy. Caffeine increases the activity of the urea cycle in the liver, augmenting ammonia degradation. By antagonizing adenosine receptors, it also has a hepatoprotective effect, impeding the formation of fibrosis, as well as having a stimulating effect on the central nervous system. The present study analyzed the effects of caffeine on the progression of cholestatic liver fibrosis and hepatic encephalopathy. Materials and methods: An experimental model of cholestatic liver fibrosis, through common bile duct ligature, and of hepatic encephalopathy, through the administration of a high-protein diet, was constructed. Male Wistar rats (n = 32) were equally divided into 4 groups. The experiment lasted 28 days, with the administration of 50 mg/kg/day of caffeine. Laboratory tests, histologic analyses of the liver and encephalon, open field tests (OFTs), and daily behavioral analyses were carried out. Results: The ligated animals treated with caffeine had lower mean transaminase levels and improved histologic aspects of the liver and encephalon. The untreated ligated animals were clearly lethargic and apathetic at the last week of the experiment, confirmed by reduced exploratory activity during the OFT. Conclusion: Caffeine improved the microarchitecture of the liver and encephalon of the cirrhotic animals and prevented the decrease in exploratory behavior of the animals during the OFT.

Summary The present study investigated the effects of chronic treatment with deoxycorticosterone-acetate (DOCA)-salt on cardiovascular responses to intravenous (i.v.) injection of the essential oil of Mentha x villosa (EOMV) in [...]

Introduction and Aims: Cirrhosis is the common outcome of liver diseases. It can be decompensated and lead to the development of complications, such as encephalopathy. Hyperammonemia that develops due to liver dysfunction is etiopathologically related to hepatic encephalopathy. Caffeine increases the activity of the urea cycle in the liver, augmenting ammonia degradation. By antagonizing adenosine receptors, it also has a hepatoprotective effect, impeding the formation of fibrosis, as well as having a stimulating effect on the central nervous system. The present study analyzed the effects of caffeine on the progression of cholestatic liver fibrosis and hepatic encephalopathy., Materials and Methods: An experimental model of cholestatic liver fibrosis, through common bile duct ligature, and of hepatic encephalopathy, through the administration of a high-protein diet, was constructed. Male Wistar rats (n=32) were equally divided into 4 groups. The experiment lasted 28 days, with the administration of 50mg/kg/day of caffeine. Laboratory tests, histologic analyses of the liver and encephalon, open field tests (OFTs), and daily behavioral analyses were carried out., Results: The ligated animals treated with caffeine had lower mean transaminase levels and improved histologic aspects of the liver and encephalon. The untreated ligated animals were clearly lethargic and apathetic at the last week of the experiment, confirmed by reduced exploratory activity during the OFT., Conclusion: Caffeine improved the microarchitecture of the liver and encephalon of the cirrhotic animals and prevented the decrease in exploratory behavior of the animals during the OFT., (Copyright © 2021 Asociación Mexicana de Gastroenterología. Published by Masson Doyma México S.A. All rights reserved.)

1. The contribution of endogenous endothelins to nociceptive responses elicited by ovalbumin (OVA) in the hind-paw of mice sensitised to this antigen (50 microg OVA+5 mg Al(OH)(3), s.c., 14 days beforehand) was investigated. 2. Sensitised mice exhibited greater nocifensive responsiveness to intraplantar (i.pl.) OVA (total licking time over first 30 min: 85.2+/-14.6 s at 0.3 microg; 152.6+/-35.6 s at 1 microg) than nonsensitised animals (29.3+/-7.4 s at 1 microg). Nocifensive responses of sensitised mice to 0.3 microg OVA were inhibited by morphine (3 mg kg(-1), s.c.) or local depletion of mast cells (four daily i.pl. injections of compound 48/80). 3. Pretreatment with i.v. bosentan (mixed ET(A)/ET(B) receptor antagonist; 52 micromol kg(-1)) or A-122722.5 (selective ET(A) receptor antagonist; 6 micromol kg(-1)) reduced OVA-induced licking from 124.8+/-20.6 s to 45.7+/-13.0 s and 64.2+/-12.1 s, respectively, whereas A-192621.1 (selective ET(B) receptor antagonist; 25 micromol kg(-1)) enhanced them to 259.2+/-39.6 s. 4. Local i.pl. pretreatment with BQ-123 or BQ-788 (selective ET(A) or ET(B) receptor antagonists, respectively, each at 3 nmol) reduced OVA-induced licking (from 106.2+/-15.2 to 57.0+/-9.4 s and from 118.6+/-10.5 to 76.8+/-14.7 s, respectively). Sarafotoxin S6c (selective ETB receptor agonist, 30 pmol, i.pl., 30 min after OVA) induced nocifensive responses in OVA-sensitised, but not in nonsensitised, animals. 5. Compound 48/80 (0.3 microg, i.pl.) induced nocifensive responses per se and potentiated those induced by i.pl. capsaicin (0.1 microg). Treatment with BQ-123 (3 nmol, i.pl.) reduced only the hyperalgesic effect of compound 48/80, whereas BQ-788 (3 nmol) was ineffective. 6. Thus, immune-mediated Type I hypersensitivity reactions elicit mast cell- and endothelin-dependent nociception in the mouse hind-paw, which are mediated locally by both ET(A) and ET(B) receptors. The nocifensive response to antigen is amenable to blockade by systemic treatment with dual ET(A)/ET(B) or selective ET(A) receptor antagonists, but is sharply potentiated by systemic selective ET(B) receptor antagonist treatment. The apparently distinct roles played by ET(B) receptors in this phenomenon at local and other sites remain to be characterised.

The present study examined the interaction between mazindol (MZ), an anorectic drug extensively used in Brazil and opioid/non-opioid endogenous analgesic systems activated by swim-stress. Further, the role of opioid, dopamine and N-methyl-D-aspartate (NMDA) receptors in mediating the analgesic effect was evaluated. The stress-induced analgesia of a 3-min swimming at 32 degrees C (opioid/non-opioid) and 20 degrees C (non-opioid) were assessed using the formalin test. Male Swiss mice were intraperitoneally injected with naloxone (1.0 mg/kg), sulpiride (3.0 mg/kg), MK-801 (0.075 mg/kg) or saline/vehicle 15 min prior, and with MZ (0.5 mg/kg) or saline/vehicle 5 min prior to swimming. The dose of MZ (0.5 mg/kg) did not cause analgesic effect, however, the association of MZ and swim-stress at both temperatures displayed synergistic interaction on analgesia that was blocked by sulpiride and MK-801 but not by naloxone. The present results suggest that MZ and swim-stress acted synergistically on analgesic responses, involving mainly the non-opioid component and possibly mediated by dopamine D2 receptors and NMDA receptors.

Cannabinoid receptor agonists significantly inhibit nociceptive responses in a large number of animal models. The present study examined whether mice displaying different basal levels of anxiety in the plus-maze test of anxiety might differ in terms of responsiveness to the antinociceptive effects of Delta(9)-tetrahydrocannabinol (Delta(9)-THC). Further, the involvement of the cannabinoid and/or opioid receptors in Delta(9)-THC-induced antinociception was investigated by using SR 141716A and naloxone, respectively, cannabinoid and opioid receptor antagonists. Delta(9)-THC-induced antinociception was evaluated in the formalin test that involves a biphasic response with an early and a late phase of high paw-licking activity. This characteristic biphasic response was observed in all control animals selected as "anxious" and "nonanxious." Delta(9)-THC (0.5-5 mg/kg i.p.) caused a dose-dependent antinociceptive effect in both groups of mice during the early and late phases. This response was fully reversed by SR 141716A (1 mg/kg i.p.) and partially reversed by naloxone (2 mg/kg i.p.). These findings suggest that mice selected for differences in anxiety-related behavior show similar responses to the antinociceptive action of Delta(9)-THC and that this action involves predominantly cannabinoid mechanisms.

The present study investigated the effects of chronic treatment with deoxycorticosterone-acetate (DOCA)-salt on cardiovascular responses to intravenous (i.v.) injection of the essential oil of Mentha x villosa (EOMV) in conscious rats. In both DOCA-salt-hypertensive and uninephrectomized control, conscious rats, i.v. bolus injections of EOMV (1 to 20 mg/kg body wt.) decreased mean aortic pressure (MAP) and heart rate (HR) in a dose-dependent manner. Treatment with DOCA-salt significantly enhanced EOMV-induced decreases in MAP, without affecting bradycardia. Likewise, both maximal percent and absolute decreases in MAP elicited by i.v. injection of the ganglion blocker, hexamethonium (30 mg/kg body wt.), were significantly greater in DOCA-salt-hypertensive than in control rats. In DOCA-salt-hypertensive rats, i.v. pretreatment with hexamethonium (30 mg/kg body wt.) reduced the bradycardia elicited by EOMV (1 to 20 mg/kg body wt.) without affecting the enhancement of EOMV-induced hypotension. These results show that i.v. treatment with EOMV decreases blood pressure in conscious DOCA-salt-hypertensive rats dose-dependently, and that this action is enhanced when compared with uninephrectomized controls. This enhancement could be related mainly to an increase in EOMV-induced vascular smooth muscle relaxation, rather than to enhanced sympathetic nervous system activity in this hypertensive model.

Purpose: This study addresses the question of epileptogenesis by investigating the effects of carbamazepine (CBZ) on the silent period of the pilocarpine model of epilepsy., Methods: Adult Wistar rats were subjected to status epilepticus (SE) induced by pilocarpine and treated with CBZ or saline, i.p, during 56 days. Latency for the first spontaneous seizure, incidence, frequency, and duration of seizures were monitored for < or =56 days after treatment. Hippocampal histologic analysis was performed., Results: CBZ reduced the frequency and duration of the seizures and the hippocampal damage., Conclusions: CBZ did not abort the epileptogenesis but minimized the expression of seizures and hippocampal damage.

Motor incoordination in the rota-rod test was used to assess the development of rapid tolerance to Delta(9)-tetrahydrocannabinol and rapid cross-tolerance between ethanol and Delta(9)-tetrahydrocannabinol in mice. Further, the influence of the cannabinoid receptor antagonist SR 141716A (N-(piperidin-1-yl)-5-(4-chlorophenyl)-4-methyl-1H-pyrazole-3-carboxyamide) on the motor impairment induced by both drugs was examined. Mice were injected on day 1 with equipotent doses of Delta(9)-tetrahydrocannabinol (28 mg/kg, i.p.) and ethanol (2.25 g/kg, i.p.) and tested at 30, 60 and 90 min after the injections. On day 2, control groups received ethanol or Delta(9)-tetrahydrocannabinol, some groups received the same treatment as the day before, while the remaining groups switched the treatment. All groups were tested to evaluate tolerance. The development of rapid tolerance to Delta(9)-tetrahydrocannabinol was observed and pretreatment with ethanol resulted in rapid cross-tolerance to Delta(9)-tetrahydrocannabinol. SR 141716A (2 mg/kg, i.p.) failed to block the development of rapid tolerance to both drugs, ethanol and Delta(9)-tetrahydrocannabinol. These results suggest that Delta(9)-tetrahydrocannabinol, similarly to ethanol, can induce rapid tolerance to motor incoordination in mice. They also support the use of the 2-day protocol as an effective procedure to reduce the length of drug exposure necessary to induce tolerance.

Endothelin-1, unlike the selective endothelin ETB receptor agonist sarafotoxin S6c, causes nociception in the rat when injected intraarticularly into the naive knee-joint. By using selective antagonists, the present study further characterizes the receptors underlying the articular nociceptive actions of endothelin-1, as well as the possible contribution of endogenous endothelins towards nociception induced by carrageenan or E. coli lipopolysaccharide (LPS) in this tissue. Nociception was evaluated by placing the animal for 1 min each hour on a revolving (3 rpm) cylinder and measuring the increase in time the hindpaw of the limb affected by the intra-articular (i.a.) injection of the nociceptive agent, failed to touch its metallic surface (i.e. paw elevation time, PET). In naive joints, endothelin-1 (120 pmol) increased the area under the PET curve (AUC 0-6 h, in arbitrary units) from 61+/-3 (control) to 156+/-12. This nociceptive effect was reduced by prior intravenous (i.v.) injection of the mixed ET(A)/ET(B)receptor antagonist bosentan (by 54 and 73% with 10 and 30 mg/kg) or i.a. administration of the selective ETA receptor antagonist BQ-123 (cyclo [D-Asp-Pro-D-Val-Leu]; by approximately/= 45% with 10 or 30 nmol), but was unaffected by the selective ET(B) receptor antagonist BQ-788 (N-cis-2,6-dimethyl-piperidinocarbonyl-L-gamma-methoxycarbonyl- tryptophanil-D-norleucine; 10 nmol). Prior joint challenge with carrageenan (300 microg) 72 h beforehand (i.e. priming) rendered the joint more sensitive to nociception induced by either endothelin-1 or sarafotoxin S6c (15, 30 and 60 pmol). Responses elicited by endothelin (30 pmol) in the primed joint were sensitive to inhibition by either BQ-123 or BQ-788 (each causing approximately/= 80% inhibition at 10 nmol). Priming also enhanced PET responses to carrageenan itself and to LPS (1 microg) markedly and persistently, increasing the area under the curve (AUC 0-12 h, in arbitrary units) from 241+/-19 to 409+/-50 and from 312+/-40 to 466+/-25, respectively (P < 0.05), without changing that measured following vehicle injection (from 121+/-3 to 117+/-4). Bosentan (up to 30 mg/kg, i.v.) failed to modify nociception caused by carrageenan or LPS in naive joints, by carrageenan in the primed joint, or control PET responses. LPS-induced nociception in the primed joint, however, was inhibited by 52 to 56% by bosentan (3 or 10 mg/kg) or 59% by local injection of the selective endothelin ET(B) receptor antagonist BQ-788 (10 nmol, i.a.), but was unaffected by the selective endothelin ETA receptor antagonist BQ-123. Thus, nociception induced by endothelin-1 in the naive joint is mediated largely via endothelin ETA receptors, whereas both ET(A)and ET(B) receptors contribute to its action in the carrageenan-primed joint. Furthermore, LPS-induced nociception in the primed joint is mediated to a large extent via endothelin release and activation of ET(B) receptors within the joint itself. These findings may be relevant to the etiology of pain underlying chronic arthritic disease in humans.

Bothrops jararaca venom (30 micrograms/site) triggered a marked inflammatory reaction in the pleural cavity that was long-lasting and reproducible. In the first 1 h after pleurisy induction, a significant decrease of total and differential cell count was observed in comparison with control values, despite the gradual enhancement of fluid leakage. A significant increase of cell migration was observed after 3 h of pleurisy induction, due to mononuclear and neutrophil cells that peaked 8 h later and this was followed by a gradual decrease, remaining elevated up to 24 h. In parallel with cell influx, a significant increase of fluid leakage that peaked between 1 and 8 h was observed, being completely abolished after 12 h following pleurisy induction. This inflammatory response was not associated in parallel with significant changes in circulating leucocyte cells and it was significantly inhibited by compound 48/80, cyproheptadine, pyrilamine, dexamethasone, indomethacin and phenidone. Preheating of the venom (100 degrees C) caused a significant decrease of both leakage of fluid and cell migration in the pleural cavity 8 h after pleurisy induction. Previous exposure to the venom (30 micrograms/site, 5 days before) produced a significant decrease of both cell migration and fluid leakage 4 h after triggering pleurisy with the same dose of the venom. Otherwise, prior daily treatment with the venom (10 micrograms/site, 4 days) resulted only in marked fluid leakage reduction 1 h after treating the animals with BJV (30 micrograms/site). These results show that the venom elicits pro-inflammatory effects in the rat pleural cavity which involve the participation of several mediators, including histamine, 5-hydroxytryptamine and products of arachidonic pathways.