Infralimbic cortex activation and motivated arousal induce histamine release.

Appetitive behaviours occur in a state of behavioural and physiological activation that allows the optimal performance of these goal-directed behaviours. Here, we tested the hypothesis that histamine neurons under the command of the infralimbic cortex are important to provide behavioural activation. Extracellular histamine and serotonin were measured by microdialysis of the medial prefrontal cortex in behaving rats in parallel with a picrotoxin microinjection into the infralimbic cortex. The injection aroused the rats behaviourally, increased histamine release and decreased serotonin levels. Inhibition of the infralimbic cortex with muscimol produced the opposite effects on neurotransmitter release. The behavioural activation induced by motivating hungry rats with caged food was paralleled by an immediate histamine release, whereas awakening induced by tapping their microdialysis bowl increased serotonin, but not histamine levels. In conclusion, picrotoxin injection into the infralimbic cortex produces behavioural activation together with histamine release; in a similar manner, induction of an appetitive state produced histamine release, likely related to increased behavioural activation characteristic of an appetitive behaviour.

Differential activation of mast cells by antigens from Trichinella spiralis muscle larvae, adults, and newborn larvae.

Mast cell (MC) hyperplasia and activation are prominent features in Trichinella spiralis infection. Indeed a temporal correlation has been shown between the kinetics of intestinal mastocytosis, release of inflammatory mediators from MC, and adult worm loss, which constitutes a major component of the defense against T. spiralis infection. It is well known that during the intestinal phase of trichinellosis, muscle larvae (ML) and adult worms (AD) enter into contact with the host; however, interaction with MC may also occur during migration of newborn larvae (NBL). Therefore, it is plausible that antigens from these developmental stages could activate MC. We have previously demonstrated by in vitro assays that T. spiralis muscle larval (TSL-1) antigens activate MC through an Ig-independent mechanism leading to the release of histamine, MC protease 5, IL-4 and TNF alpha. In this work we evaluated whether total antigens from AD or NBL could activate unsensitized MC and we compared this activation with the activation seen when MC are stimulated with TSL-1 antigens. MC activation was also tested with affinity chromatography purified antigens from NBL using the monoclonal antibody CE-4 that recognizes NBL surface components. The results obtained in this study showed that AD total extracts and TSL-1 antigens induced the release of histamine but not beta-hexosaminidase from unsensitized MC, suggesting a selective secretion of MC mediators. In contrast, NBL total extracts or purified NBL antigens did not induce the release of either histamine or beta-hexosaminidase from MC. Interestingly, AD and ML are the stages that interact with the host during the intestinal phase of infection. The mechanisms involved in TSL-1 and AD activation of unsensitized MC may function together with other mechanisms of MC activation in host protection against T. spiralis.

Leishmania (Viannia) braziliensis: human mast cell line activation induced by logarithmic and stationary promastigote derived-lysates.

Herein we investigate the ability of live promastigotes and total lysate of Leishmania (Viannia) braziliensis, derived from parasites in the logarithmic (L-Lb) or stationary phase (S-Lb), to induce human mast cell line (HMC-1) activation. In comparison with medium-treated cells, a significant histamine release was observed in HMC-1 cultures stimulated with S-Lb. Lipophosphoglycan also induced histamine release by HMC-1 cells. In immunocytochemical assays, we found a marked staining for tryptase in medium-treated HMC-1 cells, however, stimulation with L-Lb or S-Lb caused a marked decrease in the color reaction as well as in the number of tryptase-positive cells. L-Lb and S-Lb induced an evident decrease in the intracellular expression of IL-4 but not IL-12. Live stationary promastigotes were able to induce high levels of IL-4 release in HMC-1 cultures. Furthermore, these cells released significant amounts of IL-12 when incubated with both types of live promastigotes. These results indicate that L. (V.) braziliensis promastigotes differ in their ability to induce direct human mast cells activation, according to the growth phase of the parasite. Furthermore, the release of pro-inflammatory mediators and cytokines could represent an important phenomenon that might favor the initial establishment of the infection.

Evaluacion de la liberacion de Histamina para el diagnostico de alergia y farmacos mediante un metodo inmunoenzimatico competitivo (ELISA), en poblacion aparentemente sana y poblacion alergica / Evaluation of the liberation of Histamina for I diagnose of allergy to farmacos, by means of metodo inmunoenzimatico competitive (ELISA), in population apparently it heals and alergica population

La alergia a fármacos es un problema importante en salud pública, que día a día tiene mayor. repercusión en nuestra población. Lamentablemente en nuestro medio no se le otorga la debida importancia; por lo que no contamos con fuentes de referencia sobre la incidencia y las consecuencias de esta patología. Esta realidad, también la falta de procedimientos para un diagnostico correcto y de verdadero beneficio para las personas alérgicas, que permitan la identificación de él o los fármacos que potencialmente podrían causar reacciones nocivas y así permitir el uso de medicamentos sin el temor de ocasionar una reacción adversa. En este sentido, pretendimos adecuar una nueva prueba de laboratorio destinada a evaluar la liberación de histamina como una alternativa diagnóstica que sea precisa y que oriente a tomar las acciones más adecuadas en el caso de pacientes con sospecha cíe alergia

Effects of castration and testosterone replacement on peritoneal histamine concentration and lung histamine concentration in pubertal male rats.

Mast cells, which are the main source of histamine, are significantly affected by sex steroids. The present study was undertaken to determine the effects of bilateral castration and testosterone replacement on peritoneal histamine concentration and lung histamine concentration in pubertal male rats (Wistar strain). Three groups of animals were used in this study: (1) untreated castrated animals, (2) castrated animals subjected to androgen replacement by injection of propionate of testosterone, and (3) intact males as a control group. Castration alone produced a dramatic reduction in peritoneal histamine concentration. In addition, androgen replacement was effective in restoring the histamine concentration to the normal value detected in the control males (P<0.05, Kruskal-Wallis test). On the other hand, there was no significant variation in the lung histamine concentration between control males, untreated castrated males and castrated males that received androgen replacement (P<0.05, Kruskal-Wallis test). These results demonstrate for the first time that castration markedly reduces the peritoneum histamine concentration in pubertal male rats, and testosterone replacement prevents the decrease. Further, these procedures do not affect lung histamine concentration, demonstrating that mast cells from different tissues may respond differently to the same biological factors.

[Comparison of acid and pepsinogen secretion control by oxyntopeptic cell of amphibians]. / Comparación del control de la secreción de ácido y de pepsinógeno por la célula oxintopéptica del anfibio.

Pepsinogen and HCl secretion in the amphibian stomach is performed by a single cell type, the oxyntopeptic cell. The distribution of pepsinogen in gastric mucosa of Bufo marinus is heterogeneous and higher concentrations are located in the fundus. Both secretions respond to the same secretagogues. Histamine induces the highest response for the two secretions. Carbachol alone, without the endogenous histamine component, has a small effect. Forskolin and 8Br-cAMP have a similar effect to histamine. The Ca2+ ionophore, A23187, and the diacylglycerol analogue, octanoylacylglycerol (OAG) have a small effect on both secretions as carbachol. Joint addition of histamine and carbachol, or forskolin and carbachol, or of OAG and 8Br-cAMP induce a potentiated response for the two secretions. Quantitative analysis of responses and study of the relationship between them during stimulation with histamine plus carbachol revealed a non parallel and uncoupled pattern of stimulation for acid and pepsinogen secretions.

The role of histamine on the control of thyrotropin secretion in rats.

The presence of histamine (HA) in the hypothalamus, especially in its median eminence, as well as results of previous studies from this laboratory, suggest a participation of this amine in the regulation of TSH (thyroid stimulating hormone, thyrotropin) secretion. In the present investigation, rats were treated with a single injection of cimetidine (CIM - 100 mg/kg ip), an H2-HA receptor antagonist. In vitro release of TSH in response to hypothalamic extracts from control animals, was approximately 20% smaller when evoked from pituitaries obtained from CIM-treated, rather than control animals. The addition of hypothalamic extracts from CIM-treated rats to incubates of pituitaries from either control or CIM treated rats did not significantly change basal TSH secretion, suggesting that TRH (thyrotropin releasing hormone) content was decreased by the anti-histamine treatment. These results point towards a facilitatory role of HA on TSH secretion both at the hypothalamic level where it may interfere with TRH synthesis, as well as at the pituitary level where it may modify TSH response to TRH.