Expression and function of G-protein-coupled receptorsin the male reproductive tract

This review focuses on the expression and function of muscarinic acetylcholine receptors (mAChRs), α1-adrenoceptors and relaxin receptors in the male reproductive tract. The localization and differential expression of mAChR and α1-adrenoceptor subtypes in specific compartments of the efferent ductules, epididymis, vas deferens, seminal vesicle and prostate of various species indicate a role for these receptors in the modulation of luminal fluid composition and smooth muscle contraction, including effects on male fertility. Furthermore, the activation of mAChRs induces transactivation of the epidermal growth factor receptor (EGFR) and the Sertoli cell proliferation. The relaxin receptors are present in the testis, RXFP1 in elongated spermatids and Sertoli cells from rat, and RXFP2 in Leydig and germ cells from rat and human, suggesting a role for these receptors in the spermatogenic process. The localization of both receptors in the apical portion of epithelial cells and smooth muscle layers of the vas deferens suggests an involvement of these receptors in the contraction and regulation of secretion.

Esta revisão enfatiza a expressão e a função dos receptores muscarínicos, adrenoceptores α1 e receptores para relaxina no sistema reprodutor masculino. A expressão dos receptores muscarínicos e adrenoceptores α1 em compartimentos específicos de dúctulos eferentes, epidídimo, ductos deferentes, vesícula seminal e próstata de várias espécies indica o envolvimento destes receptores na modulação da composição do fluido luminal e na contração do músculo liso, incluindo efeitos na fertilidade masculina. Além disso, a ativação dos receptores muscarínicos leva à transativação do receptor para o fator crescimento epidermal e proliferação das células de Sertoli. Os receptores para relaxina estão presentes no testículo, RXFP1 nas espermátides alongadas e células de Sertoli de rato e RXFP2 nas células de Leydig e germinativas de ratos e humano, sugerindo o envolvimento destes receptores no processo espermatogênico. A localização de ambos os receptores na porção apical das células epiteliais e no músculo liso dos ductos deferentes de rato sugere um papel na contração e na regulação da secreção.

Colinomiméticos / Terapeutic effects of cholonergic substances

Atualizaçäo sobre a fisiologia, terapêutica e toxicidade dos colinomiméticos sobre o homem.

Monoamines and acetylcholine in primate cerebral cortex: what anatomy tells us about function

In primates, cholinergic and monoaminergic axons that innervate the cerebral cortex originate almost exclusively from subcortical nuclei in the brainstem and basal forebrain. These projections are thought to modulate cortical activity during arousal, attention and memory formation. Physiological and anatomical evaluations of these ascending projections suggest that they have overlapping but somewhat distinctive synaptic targets in the cortex. This review compares the anatomical organization of acetylcholine-, dopamine-, norepinephrine-, and serotonin-containing axon systems in the monkey and human cerebral cortex. Analysis of the distributions of axons, receptors, and synapses suggests that each system in likely to have a differential role in modulating cortical function.

Experimental autoimmune myocarditis: a suitable model to study neuroimmune crosstalk

This review regards the main functional characteristics of hearts subjected to an autoimmune response focusinf especially on the role of T lymphocytes and autoantibodies in the development of cardiac dysfunction. Evidence of a strong association in the onset and time-course of immune response and cardiac dysfunction is presented and the results are viewed comparatively with myocarditis models induced by heart, parasite or virus inoculation. Cardiac damage is evaluated regarding various aspects, namely histologic, immunologic, biochemical, pharmacologic, physiologic. Finally, the model, for its characteristics of resulting from an autoimmune response against the heart with functional consequences, has proved its usefulness to study neuroimmune interaction, mainly the immune to nervous direction, as autoantibodies and T cell-derived factors have a role in cardiac failure.

Participation of autonomic nervous system in the pathogenesis of Chagas disease

Evidences accumulated over the last decade give adequate proof for the existence of circulating antibodies in Chagas disease which binds to ß adrenergic and muscarinic cholinergic receptor of lymphocytes and myocardium. The interaction of the antibodies with lymphocytes and cardiac neurotransmitter receptors behaving as an agonist, triggers in the cells intracellular signal transductions that alter the physiological behaviour of this cells. These events converted the cells in pathologically active cells. Thus, antibodies activating ß adrenergic receptors of T helper (Th) lymphocytes increase cAMP and releases PGE2 by T suppressor/cytotoxic (Ts/c) cell, inducing in this way, immunosuppression by simultaneous inhibition of Th and stimulation of Ts/c cell function. All these antibodies actions were mimetized by parasite's membranes. On the other hand, the interaction of antibodies against heart ß adrenergic and cholinergic receptors trigger physiologic, morphologic, enzymatic and molecular alterations, that leading to cardiac damage. The analysis of the prevalence and distribution of these antibodies shows a strong association with seropositive asymptomatic patients with autonomic dysfunction in comparison with those asymptomatic without alteration of the heart autonomic disorders: pointing to that the presence of these antibodies may partially explain the cardiomyoneuropathy of Chagas disease, in which the sympathetic and parasympathetic systems are affected. The deoposit of autoantibodies on the myocardial neurotransmitter receptors, behaving like an agonist, could induced desensitization and/or down regulation of the receptors. This in turn, could led to a progressive blockade of myocardium neurotransmitter receptors, with sympathetic and parasympathetic dennervation, a phenomenon that has been described in the course of Chagas cardioneuropathy

Pre and post-synaptic muscarinic receptors of the rat vas deferens: an update

Los receptores muscarínicos pre- y post sinápticos del vas deferens de la rata no son M1 ya que el antagonista muscarínico M1-selectivo pirenzepina (PZ) posee baja afinidad por ambos. Basándonos en este hecho las dos acciones de ACh, pre-0y post-sinápticas, en esta preparación parecen ser mediadas por receptores muscarínicos parecidos al subtipo M2. La siguiente serie de observaciones experimentales revelan que ambas respuestas son mediadas por receptores muscarínicos farmacológicamente distintos. El rango de orden de potencia desplegado por 3 antagonistas muscarínicos (Atropina, N-metil-escopolamina [NMS] y PZ) en cada uno de estos lugares son diferentes. Atropina y PZ son bloqueadores selectivos del receptor muscarínico presente en músculo liso. NMS es un antagonista selectivo del receptor pre-sináptico muscarínico que facilita la liberación de norepinefrina. Por último, PZ y NMS despliegan un antagonismo diferencial, siendo competitivos y no-competitivos pre- y post-sinápticamente, respectivamente. Los resultados sugieren que el receptor muscarínico post-sináptico presente en el músculo liso pertenece a los subtipos M2B (oM3). El receptor pre-sináptico pertenece a los subtipos M2A (o M2) o a una subclase de los receptores muscarínicos M2B (o M3)

La actividad de enlace del receptor muscarínico: influencia de los iones monovalentes / Connection activity of muscarinic receptor: influence of the monovalent ions

Muchas funciones biológicas y muchos mecanismos de control tales como las reacciones enzimáticas y las interacciones de receptores con neurotransmisores y hormonas, se activan luego de pequeños ligandos se unen a macromoléculas. Es por eso importante comprender cómo la concentración de un ligando puede afectar la respuesta biológica, e imprescindible conocer a fondo los factores que afectan esta relación ligando-receptor la cual inicia los cambios que se producen en la fisiología celular. Así, en este trabajo se estudió el efecto del Na y del Li sobre la capacidad de enlace del benzilato de quinuclidinilo (QNB) con el receptor muscarínico de la acetilcolina (ACh) presente en fracciones de membrana de músculo liso de tráquea de bovino. El QNB es un antagonista de la ACh y se ha demostrado que su actividad de enlace con el receptor muscarínico presenta una alta afinidad, es específica y es saturable. Del análisis de Hill para los experimentos realizados con el D-L-3H-QNB en condiciones basales resultó una constante (Ka) de 1,52nM y un número de Hill (NH) de 1,30. La adición de Na y Li aumentó la capacidad máxima de unión del sistema, el valor del NH fue de 1,61 cuando se agregó NaCI y 1,27 cuando se agregó LiCl. En los experimentos realizados con el L-3H-QNB en condiciones basales se encontró un valor de NH 1,29. Este valor es similar al encontrado cuando se usó el racemato. Por otra parte, al igual que con el D-L-3H-QNB, la adición de NaCl aumenta la cantidad máxima de ligando que puede unirse a los receptores muscarínicos, mientras que la adición de LiCl no la modifica de manera apreciable ..