Amebic liver abscess in rat: morphological evidence of innate immune modulation by the sympathetic nervous system / Absceso hepático amebiano en rata: evidencia morfológica de la modulación de la respuesta inmune innata por el sistema nervioso simpático

All organs of the immune system are innervated and almost all neurotransmitter receptors are present on immune cells. We studied the effects of sympathetic innervation in the development of amebic liver abscess (ALA) in rats. Our results showed that lack of sympathetic innervation promote a decrease in size of ALA. We found scarce amoebas, increased the number of neutrophils and a few collagen fibers surrounding the abscess, meanwhile in control group, we observed abscesses areas with typical necrosis including trophozoites and neutrophils. Macrophages were differentially distributed surrounding abscess area in control and vehicle groups, but equally located in and outside of the abscesses in sympathectomized rat. No significant differences were observed on NK cells in analysed groups. In cytokines quantification studies, we observed down-expression of IFN-g and TNF-a, moreover, we found overexpression of IL-10 in sympathectomized and ALA group. In conclusion, our results suggest that elimination of sympathetic nerve fibers in a model rat of amebic liver abscess induces reduction of the innate immune response and presence of amebas through the liver at seven days post-inoculation.

Todos los órganos del sistema inmune están inervados y casi todos los receptores para neurotransmisores están presentes en las células de la respuesta inmune. Nosotros estudiamos el efecto de la inervación simpática en el desarrollo del Absceso Hepático Amebiano (AHA) en ratas. Nuestros resultados muestran que la inervación simpática promueve una disminución en el tamaño del AHA. Nosotros encontramos áreas fibróticas bien definidas con algunas amibas, mayor número de neutrófilos y pocas fibras de colágena rodeando el área de daño, mientras que en el grupo control, nosotros observamos áreas con necrosis, trofozoítos y pocos neutrófilos en el área fibrótica. Los macrófagos se observaron distribuidos en el área fibrótica en los animales simpatectomizados, mientras que en los controles encontramos a los macrófagos distribuidos en la periferia del absceso. No se encontró diferencia significativa en la distribución y cantidad de células NK. En el estudio de citocinas nosotros observamos una disminución de IFN-g y TNF-a y un incremento de IL-10 en animales simpatectomizados. En conclusión, nuestros resultados sugieren que la eliminación de las fibras del sistema nervioso simpático en el modelo de AHA en rata, reduce la respuesta inmune innata y persisten amebas en el tejido dañados a los 7 días post-inoculación.

Modulation of pineal activity during the 23rd sunspot cycle: Melatonin rise during the ascending phase of the cycle is accompanied by an increase of the sympathetic tone.

In two groups of female CD-rats nocturnal urine (19-23 h, 23-3 h, 3-7 h) was collected at monthly intervals over 658 days (I: 1997-1999) and 494 days (II: 1999-2000) coinciding with the ascending limb (1996-2000) of the 23rd sunspot cycle (1996-2008). The excretion of 6-sulfatoxymelatonin (aMT6s: I, II) was determined as well as the ratio of noradrenaline/adrenaline (NA/A: I) reflecting the activity of the sympathetic nervous system. AMT6s was higher in II than I (19-7 h: +24%; P<0.001; 23-3 h: +30% and 3-7 h: +17%, P<0.001), and progressively increased (19-23 h) showing linear regressions (I: R=+0.737, P=0.003; II: R=+0.633, 0.008) which correlated (I) with the Planetary Index (Ap: R=+0.598, P=0.020), an established estimate of geomagnetic disturbances due to solar activity. NA/A rose at all intervals (I: 46-143%) correlating with Ap (R=+0.554-0.768; P=0.0399-0.0013). These results indicate that melatonin secretion rises as solar activity increases during the ascending limb of a sunspot cycle accompanied by growing geomagnetic disturbances (Ap) which elevate the sympathetic tone and thus affect the pineal gland, initially stimulating the activity of arylalkylamine N-acetyltransferase and subsequently fostering the expression of N-acetylserotonin O-methyltransferase (rate-limiting enzyme for melatonin biosynthesis) if Ap increases further. The potential (patho) physiological significance of these findings is discussed and the need for a systematic continuation of such studies is emphasized.

Pressão arterial, respostas metabólicas e autonômicas à insulina e infusão de intralipid® em pacientes chagásicos / Blood pressure, metabolic and autonomic responses to insulin and intralipid® infusion in chagasic patients / Presión arterial, respuestas metabólicas y autonómicas a la insulina e infusión de intralipid® en pacientes chagásicos

FUNDAMENTO: Infusão de intralipid e heparina resulta em aumento da pressão arterial e também em anormalidades autonômicas em indivíduos normais e hipertensos. OBJETIVO: Avaliar a sensibilidade a insulina e o impacto da infusão de intralipid e de heparina (ILH) sobre a resposta hemodinâmica, metabólica e autonômica em pacientes com a forma indeterminada da doença de Chagas. MÉTODOS: Doze pacientes com a forma indeterminada da doença de Chagas e 12 voluntários saudáveis foram avaliados. RESULTADOS: A pressão arterial basal e a frequência cardíaca foram semelhantes nos dois grupos. Os níveis plasmáticos de noradrenalina encontravam-se ligeiramente aumentados no grupo de pacientes chagásicos. Após o Teste de Tolerância a Insulina (TTI), houve um declínio significativo na glicose dos dois grupos. A Infusão de ILH resultou em aumento da pressão arterial em ambos os grupos, mas não houve nenhuma mudança significativa na noradrenalina plasmática. O componente de Baixa Frequência (BF) mostrou-se semelhante e aumentou de forma semelhante em ambos os grupos. O componente de Alta Frequência (AF) apresentou-se menor no grupo chagásico. CONCLUSÃO: Pacientes com forma indeterminada da doença de Chagas apresentaram aumento da atividade simpática no momento basal e uma resposta inadequada à insulina. Eles também tiveram um menor componente de alta frequência e sensibilidade barorreflexa prejudicada no momento basal e durante a infusão de intralipid e heparina.

BACKGROUND: Intralipid and heparin infusion results in increased blood pressure and autonomic abnormalities in normal and hypertensive individuals. OBJECTIVE: To evaluate insulin sensitivity and the impact of Intralipid and heparin (ILH) infusion on hemodynamic, metabolic, and autonomic response in patients with the indeterminate form of Chagas' disease. METHODS: Twelve patients with the indeterminate form of Chagas' disease and 12 healthy volunteers were evaluated. RESULTS: Baseline blood pressure and heart rate were similar in both groups. Plasma noradrenaline levels were slightly increased in the Chagas' group. After insulin tolerance testing (ITT), a significant decline was noted in glucose in both groups. ILH infusion resulted in increased blood pressure in both groups, but there was no significant change in plasma noradrenaline. The low-frequency component (LF) was similar and similarly increased in both groups. The high-frequency component (HF) was lower in the Chagas' group. CONCLUSION: Patients with the indeterminate form of Chagas' disease had increased sympathetic activity at baseline and impaired response to insulin. They also had a lower high-frequency component and impaired baroreflex sensitivity at baseline and during Intralipid and heparin infusion.

FUNDAMENTO: La Infusión de intralipid® y de heparina trae como resultado un aumento de la presión arterial y también de las anormalidades autonómicas en los individuos normales e hipertensos. OBJETIVO: Evaluar la sensibilidad a la insulina y el impacto de la infusión de intralipid® y de heparina (ILH) sobre la respuesta hemodinámica, metabólica y autonómica en pacientes con la forma indefinida de la Enfermedad de Chagas. MÉTODOS: Fueron evaluados doce pacientes con la forma indefinida de la Enfermedad de Chagas y 12 voluntarios sanos. RESULTADOS: La presión arterial basal y la frecuencia cardíaca fueron similares en los dos grupos. Los niveles plasmáticos de noradrenalina estaban ligeramente más elevados en el grupo de pacientes chagásicos. Después del Test de Tolerancia a la Insulina (TTI), se produjo una ostensible disminución en la glucosa de los dos grupos. La Infusión de ILH trajo como consecuencia el aumento de la presión arterial en ambos grupos, pero no hubo ningún cambio significativo en la noradrenalina plasmática. El componente de Baja Frecuencia (BF), fue similar y aumentó de forma parecida en ambos grupos. El componente de Alta Frecuencia (AF) se presentó con un menor nivel en el grupo chagásico. CONCLUSIONES: Los pacientes con una forma indeterminada de la Enfermedad de Chagas, presentaron un aumento en la actividad simpática al momento basal y una respuesta inadecuada a la insulina. También tuvieron un menor componente de alta frecuencia y de sensibilidad barorrefleja, que fue perjudicado en el momento basal y durante la infusión de intralipid® y heparina.

The inhibitory role of sympathetic nervous system in the Ca2+-dependent proteolysis of skeletal muscle

Mammalian cells contain several proteolytic systems to carry out the degradative processes and complex regulatory mechanisms to prevent excessive protein breakdown. Among these systems, the Ca2+-activated proteolytic system involves the cysteine proteases denoted calpains, and their inhibitor, calpastatin. Despite the rapid progress in molecular research on calpains and calpastatin, the physiological role and regulatory mechanisms of these proteins remain obscure. Interest in the adrenergic effect on Ca2+-dependent proteolysis has been stimulated by the finding that the administration of β2-agonists induces muscle hypertrophy and prevents the loss of muscle mass in a variety of pathologic conditions in which calpains are activated. This review summarizes evidence indicating that the sympathetic nervous system produces anabolic, protein-sparing effects on skeletal muscle protein metabolism. Studies are reviewed, which indicate that epinephrine secreted by the adrenal medulla and norepinephrine released from adrenergic terminals have inhibitory effects on Ca2+-dependent protein degradation, mainly in oxidative muscles, by increasing calpastatin levels. Evidence is also presented that this antiproteolytic effect, which occurs under both basal conditions and in stress situations, seems to be mediated by β2- and β3-adrenoceptors and cAMP-dependent pathways. The understanding of the precise mechanisms by which catecholamines promote muscle anabolic effects may have therapeutic value for the treatment of muscle-wasting conditions and may enhance muscle growth in farm species for economic and nutritional purposes.

Effect of inhibition of nitric oxide synthase on blood pressure and renal sodium handling in renal denervated rats

The role of sympathetic nerve activity in the changes in arterial blood pressure and renal function caused by the chronic administration of NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, was examined in sham and bilaterally renal denervated rats. Several studies have demonstrated that sympathetic nerve activity is elevated acutely after L-NAME administration. To evaluate the role of renal nerve activity in L-NAME-induced hypertension, we compared the blood pressure response in four groups (N = 10 each) of male Wistar-Hannover rats weighing 200 to 250 g: 1) sham-operated vehicle-treated, 2) sham-operated L-NAME-treated, 3) denervated vehicle-treated, and 4) denervated L-NAME-treated rats. After renal denervation or sham surgery, one control week was followed by three weeks of oral administration of L-NAME by gavage. Arterial pressure was measured weekly in conscious rats by a tail-cuff method and renal function tests were performed in individual metabolic cages 0, 7, 14 and 21 days after the beginning of L-NAME administration. L-NAME (60 mg kg-1 day-1) progressively increased arterial pressure from 108 + or - 6.0 to 149 + or - 12 mmHg (P<0.05) in the sham-operated group by the third week of treatment which was accompanied by a fall in creatinine clearance from 336 + or - 18 to 222 + or - 59 µl min-1 100 g body weight-1 (P<0.05) and a rise in fractional urinary sodium excretion from 0.2 + or - 0.04 to 1.62 + or - 0.35 per cent (P<0.05) and in sodium post-proximal fractional excretion from 0.54 + or - 0.09 to 4.7 + or - 0.86 per cent (P<0.05). The development of hypertension was significantly delayed and attenuated in denervated L-NAME-treated rats. This was accompanied by a striking additional increase in fractional renal sodium and potassium excretion from 0.2 + or - 0.04 to 4.5 + or - 1.6 per cent and from 0.1 + or - 0.015 to 1.21 + or - 0.37 per cent, respectively, and an enhanced post-proximal sodium excretion compared to the sham-operated group. These differences occurred despite an unchanged creatinine clearance and Na+ filtered load. These results suggest that bilateral renal denervation delayed and attenuated the L-NAME-induced hypertension by promoting an additional decrease in tubule sodium reabsorption in the post-proximal segments of nephrons. Much of the hypertension caused by chronic NO synthesis inhibition is thus dependent on renal nerve activity.

Does the release of tritiated noradrenaline accuratelly reflect the realease of endogenous noradrenaline from rat vas deferens nerve terminals?

To determine whether the release of tritiated noradrenaline (NA) from the sympathetic nerve terminals of the rat vas deferens is an accurate reflection of the release of endogenous NA, we compared the electrically-evoked release of tritiated and endogenous NA from the prostatic sections of the vasa deferentia of male rats. We found that while the release of tritiated NA was completely dependent on the presence of calcium, the release of endogenous NA was not. The overflow of both, tritiated and endogenous NA, was virtually unaffected by blockade of the neuronal uptake mechanism by desipramine. In contrast, blockade of the extraneuronal uptake greatly increased the overflow of endogenous NA, while having no effect on the overflow of tritiated NA. Tritiated NA release, on the other hand, was sensitive to prejunctional regulation, while the release of endogenous NA was not. Increases in stimulus train duration induced a significant increase in the release of endogenous NA, but not in that of tritiated NA. In contrast, the later responded to lower stimulus train frequencies and reached a plateau at lower frequency values as compared to the endogenous NA release. Our results indicate the existence of marked differences between the release of tritiated and endogenous NA. We conclude that: 1) the assumption that tritiated NA release provides a good marker for endogenous NA release in the rat was deferens seems unwarranted; 2) the use of endogenous NA to study the release process in the vas deferens requires a re-examination of the experimental conditions used, in order to minimize possible artifacts that may obscure the study of neuronal release; 3) the choice between measuring the release of tritiated or endogenous NA must be evaluated for each tissue in particular, taking into account its cytoarchitecture, as well as the experimental conditions used

The innervation of the thymus gland in the rat: a HRP study

The marker horseradish peroxidase (HRP) was used to retrogradely label the cell bodies of origin of the nerve fibers responsible for thymic innervation. The thymus was exposed in albino rats under general anesthesia and a conjugate of HRP-WGA was injected bilaterally into the gland parenchyma. After a survival time of 3 days, the animals were anesthetized and perfused transcardially. Their brainstems were removed and serially sectioned and together with the whole sympathetic chains were processed for HRP demonstration. Labeled cell bodies were identified in the brainstem at the level of the retrofacial and ambiguous nuclei bilaterally. In the sympathetic chain, labeled neurons were present from the first cervical to the ninth thoracic ganglion, although they were detected in higher numbers in the superior cervical and stelate ganglia.

Mechanism of decrease in heart rate by peripheral dopaminergic D2-receptors

We performed this study in order to verify the heart rate decrease caused by the D2-receptor on cardiac sympathetic nerve endings and its relation to the concentration of norepinephrine in synaptic clefts. Sprague-Dawley rats were pithed and the heart rate was increased either by electrical stimulation of the cardiac accelerator nerve or by intravenous infusion of norepinephrine, tyramine, or isoproterenol. Increased heart rate by electrical stimulation of cardiac accelerator nerve was dose-dependently lowered by lisuride and its effect was blocked by pretreatment with sulpiride but not with yohimbine and SCH 23390. Also, the heart rate was decreased in a dose-dependent manner by clonidine and this effect was blocked by pretreatment with yohimbine, but not with sulpiride. For increased heart rate by infusion of norepinephrine, tyramine, or isoproterenol, the heart rate lowering effect of lisuride was more marked in the norepinephrine-and tyramine-infusion groups, in which the intrasynaptic concentration of norepinephrine was elevated, compared to the isoproterenol-infusion group, in which intrasynaptic concentration of norepinephrine was not elevated. In conclusion, there is a D2-receptor on the cardiac sympathetic nerve endings which decreases the heart rate and is different from the presynaptic alpha 2-receptor. Also, the heart rate lowering effect via stimulation of the D2-receptor by lisuride was more marked with increased concentration of norepinephrine in the synaptic cleft.

Valoración del tono simpático en la hipertensión esencial mediante la prueba de supresión por clonidina / Evaluation of the sympathetic tone in essential hypertension by the clonidine-supression test

Evidencias recientes sugieren que el sistema nervioso simpático juega un papel importante en la patogenia y en mantenimiento de diversas formas de enfermedad hipertensiva. La prueba de supresión por clonidina permite exhibir cambios sutiles en la liberación de noradrenalina neuronal en la hipertensión esencial. Para confirmar lo anterior se seleccionaron 16 pacientes: 7 con hipertensión fronteriza (HF) (4 varones y 3 mujeres) con edad promedio de 24 años y 9 con hipertensión establecida (HE) (6 varones y 3 mujeres) con edad de 25 años. En ambos grupos, se registró la frecuencia cardiaca (FC) y la presión arterial (PA) cada 30 min y por cánula intravenosa se midieron las catecolaminas plasmásticas (CAP) y la actividad de renina plasmática (ARP) antes y después (180 y 240 min) de haber sido administrada una dosis oral de clonidina (300 mcg). Los pacientes permanecieron en clinostatismo hasta los 180 min y en ortostatismo durante 1 hora hasta los 240 min. La FC y la PA disminuyeron en los HF e HE después de la clonidina durante el clinostatismo, en comparación al período preclonidina. Las CAP también mostraron reducción a los 180 min con respecto al periodo basal. La ARP no presentó cambio a los 180 min en ambos grupos, con relación al tiempo 0. Durante el ortostatismo, la FC aumentó en los 2 grupos con respecto al período basal. La PA permaneció disminuida con relación al tiempo basal. La CAP se incrementaron con respecto al período preclonidina. La ARP mostró tendencia discreta a aumentar con relación a los 0 min en ambos grupos. Los niveles basales de CAP no son índices confiables de la participación del tono simpático en el mantenimiento de cifras elevadas de PA en la enfermedad hipertensiva. La prueba de clonidina demuestra que la actividad simpática puede ser un factor común en la patogenia de diversas variedades clínicas de hipertensión esencial y que los mecanismos involucrados en el origen y desarrollo de la enfermedad, yacen en las porciones superiores del sistema nervioso central