Expression of cell adhesion molecules, chemokines and chemokine receptors involved in leukocyte traffic in rats undergoing autoimmune orchitis.

The testis is considered an immunologically privileged site where germ cell antigens are protected from autoimmune attack. Yet in response to infections, inflammatory diseases, or trauma, there is an influx of leukocytes to testicular interstitium. Interactions between endothelial cells (EC) and circulating leukocytes are implicated in the initiation and evolution of inflammatory processes. Chemokines are a family of chemoattractant cytokines characterized by their ability to both recruit and activate cells. Thus, we investigated the expression of CCL3, its receptors, and adhesion molecules CD31 and CD106 in an in vivo model of experimental autoimmune orchitis (EAO). In EAO, the highest content of CCL3 in testicular fluid coincides with onset of the disease. However, CCL3 released in vitro by testicular macrophages is higher during the immunization period. The specific chemokine receptors, CCR1 and CCR5, were expressed by testicular monocytes/macrophages and an increased number of CCR5+ cells was associated with the degree of testicular lesion. EC also play an essential role by facilitating leukocyte recruitment via their ability to express cell surface adhesion molecules that mediate interactions with leukocytes in the bloodstream. Rats with EAO showed a significant increase in the percentage of CD31+ EC that upregulate the expression of CD106. The percentage of leukocytes isolated from peripheral blood and lymph nodes expressing CD49d (CD106 ligand) also increases during orchitis. These data suggest that cell adhesion molecules, in conjunction with chemokines, contribute to the formation of a chemotactic gradient within the testis, causing the leukocyte infiltration characteristic of EAO histopathology.

Impaired expression and distribution of adherens and gap junction proteins in the seminiferous tubules of rats undergoing autoimmune orchitis.

Experimental autoimmune orchitis (EAO) is characterized by an interstitial lymphomononuclear cell infiltration and a severe lesion of seminiferous tubules (ST) with germ cells that undergo apoptosis and sloughing. The aim of this study was to analyse the expression and localization of adherens junction (AJ) proteins: N-cadherin, α-, ß- and p120 catenins and gap junction protein, connexin 43 (Cx43), to explore some aspects of germ-cell sloughing during the development of orchitis. EAO was induced in Sprague-Dawley adult rats by active immunization with testicular homogenate and adjuvants. Control rats (C) were injected with saline solution and adjuvants. Concomitant with early signs of germ-cell sloughing, we observed by immunofluorescence and Western blot, a delocalization and a significant increase in N-cadherin and α-catenin expression in the ST of EAO compared with C rats. In spite of this increased AJ protein expression, a severe germ-cell sloughing occurred. This is probably due to the impairment of the AJ complex function, as shown by the loss of N-cadherin/ß-catenin colocalization (confocal microscopy) and increased pY654 ß-catenin expression, suggesting lower affinity of these two proteins and increased pERK1/2 expression in the testis of EAO rats. The significant decrease in Cx43 expression detected in EAO rats suggests a gap junction function impairment also contributing to germ-cell sloughing.

Adenosine regulates Sertoli cell function by activating AMPK.

This work evaluates adenosine effects on Sertoli cell functions, which are different to those resulting from occupancy of purinergic receptors. The effects of adenosine and N(6)-cyclohexyladenosine (CHA) - an A(1) receptor agonist resistant to cellular uptake - on Sertoli cell physiology were compared. Adenosine but not CHA increased lactate production, glucose uptake, GLUT1, LDHA and MCT4 mRNA levels, and stabilized ZO-1 protein at the cell membrane. These differential effects suggested a mechanism of action of adenosine that cannot be solely explained by occupancy of type A(1) purinergic receptors. Activation by adenosine but not by CHA of AMPK was observed. AMPK participation in lactate production and ZO-1 stabilization was confirmed by utilizing specific inhibitors. Altogether, these results suggest that activation of AMPK by adenosine promotes lactate offer to germ cells and cooperates in the maintenance of junctional complex integrity, thus contributing to the preservation of an optimum microenvironment for a successful spermatogenesis.

Expression of caveolin-1 in rat Leydig cells

Caveolin-1, the first member of caveolin family reported, is recognized as the structural component of caveola, a plasma membrane invagination or vesicles that are a subcompartment distinct from clathrin-coated pits. This protein is also known to be involved in cholesterol trafficking. The aim of this study was to determine the expression of caveolin-1 in adult rat Leydig cells. Testis sections incubated with an antibody to caveolin-1 showed, by immunohistochemistry, a moderate number of Leydig cells with different degrees of immunoreaction and a strong reaction in endothelial cells and in the lamina propia of seminiferous tubules.Caveolin- 1 was detected in the cell cytoplasm with a granular pattern and on the cell surface of Leydig cells cultured 24 h on uncoated, laminin-1 or type IV collagen coated coverslips. We also observed a milder reaction in 3 h cultures. Immunoreaction was also detected in Leydig cells with an antibody to tyrosine-phosphorylated caveolin-1. By double immunofluorescent technique, we observed co-localization of caveolin- I and 313-hydroxysteroid dehydrogenase. Western blot analysis revealed a band of about 22 kDa molecular weight that was recognized with both caveolin-1 and tyrosine-phosphocaveolin-1 antibodies. Caveolin-l is one of a few proteins with ademonstrated ability to bind cholesterol in vivo. In this context, the presence of caveolin- in Leydig cells may be related to cholesterol traffic--a rate limiting step in steroid biosynthesis.

Expression of caveolin-1 in rat Leydig cells

Caveolin-1, the first member of caveolin family reported, is recognized as the structural component of caveola, a plasma membrane invagination or vesicles that are a subcompartment distinct from clathrin-coated pits. This protein is also known to be involved in cholesterol trafficking. The aim of this study was to determine the expression of caveolin-1 in adult rat Leydig cells. Testis sections incubated with an antibody to caveolin-1 showed, by immunohistochemistry, a moderate number of Leydig cells with different degrees of immunoreaction and a strong reaction in endothelial cells and in the lamina propia of seminiferous tubules.Caveolin- 1 was detected in the cell cytoplasm with a granular pattern and on the cell surface of Leydig cells cultured 24 h on uncoated, laminin-1 or type IV collagen coated coverslips. We also observed a milder reaction in 3 h cultures. Immunoreaction was also detected in Leydig cells with an antibody to tyrosine-phosphorylated caveolin-1. By double immunofluorescent technique, we observed co-localization of caveolin- I and 313-hydroxysteroid dehydrogenase. Western blot analysis revealed a band of about 22 kDa molecular weight that was recognized with both caveolin-1 and tyrosine-phosphocaveolin-1 antibodies. Caveolin-l is one of a few proteins with ademonstrated ability to bind cholesterol in vivo. In this context, the presence of caveolin- in Leydig cells may be related to cholesterol traffic--a rate limiting step in steroid biosynthesis.(AU)

Involvement of CD44 in leukocyte recruitment to the rat testis in experimental autoimmune orchitis.

Experimental autoimmune orchitis (EAO) is characterized by an interstitial mononuclear cell infiltrate and a severe lesion of the seminiferous tubules with germ cells that undergo apoptosis and sloughing. The aim of this study was to determine the role of CD44 in testicular leukocyte recruitment in EAO. The biological functions of CD44 have been attributed to the generation of a functionally active hyaluronan-binding phenotype. Orchitis was induced in Sprague-Dawley adult rats by active immunization with an emulsion of testicular homogenate and complete Freund's adjuvant using Bordetella pertussis as co-adjuvant. Control rats (C) injected with saline and adjuvants and normal (N) untreated rats were also studied. CD44 expression was analyzed by flow cytometry in peripheral blood mononuclear cells (PBMC) and lymph node cells isolated from rats at different times after the first immunization. We observed an increase in the mean fluorescence intensity of both samples in the C and experimental (E) groups only after the immunization period. A significant decrease in percentage of CD44+PBMC and in mean fluorescence intensity was observed in rats with orchitis compared with the C group. By in vitro hyaluronic acid-binding assay we demonstrated that the percentage of PBMC adhesion was higher in the E group compared with the C and N groups. By immunohistochemistry, we observed a significant increase in the number of CD44+cells in the testicular interstitium of rats with severe orchitis compared with the N and C groups. These results suggested that the CD44 molecule is involved in the homing of lymphomonocytes into the testes of rats with autoimmune orchitis.

Passive immunization with anti-laminin immunoglobulin G modifies the integrity of the seminiferous epithelium and induces arrest of spermatogenesis in the guinea pig.

In the testis, the base of the Sertoli cells is in contact with the basement membrane matrix, in which the laminins constitute the major noncollagenous components. We have previously demonstrated that antibodies against a preparation enriched in basement membranes of seminiferous tubules (STBM) or a noncollagenous fraction of STBM passively transferred induced modifications to the basement membranes and focal sloughing of the seminiferous epithelium in the rat. In the present report, we tested the effect of passive immunization with anti-laminin IgG on the limiting membrane of the seminiferous tubules, spermatogenesis, and maintenance of the blood-testis barrier in the adult guinea pig. Rabbit antibodies to laminin 1 (IgG fraction) were injected in adult male guinea pigs (GP). Nonimmunized GP and GP immunized with normal rabbit serum IgG were used as controls. Measurements of variations in the diameter and lumen of the tubules and in the size of individual components of the tubular limiting membrane showed that the highest percentage of tubules with reduced lumen occurred 30 days after passive immunization with anti-laminin, when the limiting membrane was thickest and lesions to the seminiferous epithelium were most severe. The lesions included thickening of the limiting membrane, infolding in the basal lamina, deposits of immune complexes coincident with sloughing of pachytene spermatocytes and spermatids, and vacuolization of the Sertoli cells. Mononuclear cell infiltration of the tubules was rare. Permeability tracer studies revealed that Sertoli cell tight junctions remained impermeable. Fifty and 80 days after treatment, the basement membrane of the tubules and the progression of the spermatogenesis were normal. Passive immunization with anti-laminin IgG provided a valuable experimental model for the in vivo study of the influence of the basement membrane on the issue of spermatogenesis and the integrity of the seminiferous epithelium.

Immunodetection of cell adhesion molecules in rat Sertoli cell cultures.

PROBLEM: The presence of cell adhesion molecules (CAMs) in Sertoli cells has not been explored extensively. The expression of CAMs involved in cell-matrix and cell-to-cell interactions in Sertoli cell cultures was examined. METHOD OF STUDY: Immunohistochemical and Western blot techniques were applied to rat Sertoli cell cultures using specific antibodies to alpha 3, alpha 5, and alpha 6 integrin subunits; NCAM; and cadherins. RESULTS: Expression of alpha 3 and alpha 6 integrin subunits (mainly laminin receptors) and lack of expression of alpha 5 integrin subunit (fibronectin receptor) was observed in Sertoli cells by immunohistochemistry. These cells also expressed neural CAM (NCAM) and N-cadherin. By Western blot analysis, Sertoli cell extracts reacted with antibodies to alpha 3 integrin subunit revealed a band approximately 130 kDa, whereas no expression of alpha 5 integrin subunit was detected. Cell extracts incubated with antibodies to pan cadherin exhibited a band approximately 120 kDa, whereas bands of 180, 140, and 120 kDa were observed with antibodies to NCAM. CONCLUSION: New data about the expression of receptors for extracellular matrix proteins (alpha 3 and alpha 6 integrin subunits) as well as cell-to-cell adhesion molecules (NCAM and cadherins) are reported in rat Sertoli cell cultures.

Immunodetection of cell adhesion molecules and extracellular matrix proteins in rat Leydig cell cultures.

Cell adhesion molecules (CAMs) as well as extracellular matrix (ECM) proteins were identified in Leydig cell cultures using immunohistochemical and Western blot analysis. Leydig cells were isolated from 60-day-old rats and cultured for 4 days. For immunofluorescence and immunoperoxidase techniques, Leydig cells were incubated with antisera to ECM proteins (antibodies to laminin, type IV collagen and fibronectin); antisera to integrins (antibodies to beta 1, alpha 3, alpha 5 and alpha 6 integrin subunits) and antisera to cell-to-cell adhesion molecules (antibodies to N-CAM and N-cadherin). Results of the two immunohistochemical techniques were similar. Laminin and type IV collagen were detected in the perinuclear area of Leydig cell cytoplasm and cell processes as bright granular immunofluorescence or as a brown reaction product using the immunoperoxidase technique. Leydig cells expressed alpha 3 and alpha 6 integrin subunits (mainly laminin receptors), while no reaction was detected with antibodies to the alpha 5 integrin subunit (fibronectin receptor). Leydig cells also expressed cell-to-cell adhesion molecules such as N-CAM and N-cadherin. Using Western blot analysis, Leydig cell extracts incubated with antibodies to laminin revealed two bands of around 200 kDa, which is characteristic of laminin 1 light chains. A band with electrophoretic mobility similar to that of the alpha 2 (IV) collagen chain from EHS sarcoma and a band of around 230 kDa similar to fibronectin were also detected in Leydig cell extracts using specific antisera. Leydig cells incubated with antibodies to the alpha 3 integrin subunit revealed two bands below 120 kDa. Finally, Western blot results showed that Leydig cells expressed N-CAM as two faint bands of around 140 kDa and N-cadherin as a 120 kDa band. The present data suggest that Leydig cells in culture are able to synthesize ECM proteins and express ECM receptors (integrins), as well as cell-to-cell adhesion molecules such as N-CAM and N-cadherin.

Participation of cytoskeleton in the effect of antilaminin IgG on cardiac cholinoceptors.

1. We have previously demonstrated a molecular relationship between laminin and cardiac cholinoceptors. 2. We have now explored the participation of cytoskeletal proteins in the interaction between an antilaminin IgG with cardiac cholinoceptors. 3. Antilaminin IgG, whilst it specifically reacts with laminin molecules was able to induce cardiac cholinoceptor activation; acting like an agonist, decreasing cyclic AMP concentrations, reducing heart contractility and increasing phosphoinositide turnover. 4. Antilaminin IgG also interfered with the binding of a radiolabelled muscarinic antagonist, [3H]-quinuclidinyl benzilate. Colchicine and cytochalasin B, drugs that are able to prevent microfilament and microtubule polimerization, impaired the binding of antilaminin IgG to muscarinic cholinoceptors. 5. Cytochalasin B but not colchicine modified the muscarinic cholinoceptor effects mediated by regulatory G proteins (cyclic AMP and contractility) induced by antilaminin IgG. 6. It was demonstrated, by immunofluorescence, that none of these disrupting drugs altered the specific recognition of the antibody by its antigen. 7. These data indirectly suggest the participation of the cytoskeleton in the laminin and cholinergic receptor association.

Role of laminin on prolactin and gonadotrophin release from anterior pituitaries of male rats.

The effect of rat laminin on the release of prolactin (PRL), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from anterior pituitaries of adult male rats was studied in vitro. Laminin had a bidirectional effect on basal release of PRL, being stimulatory at 10(-12)M and inhibitory at 10(-9) and 10(-8)M. LH release was only stimulated by the 10(-12)M concentration and no changes in FSH release were observed. Laminin did not modify the stimulatory action of thyrotropin-releasing hormone (TRH) nor luteinizing hormone releasing hormone (LHRH), but the response of FSH to LHRH was inhibited with a maximal effect at 10(-10)M. To assess its physiological role, the effect of a rabbit antibody to laminin on the release of PRL, LH and FSH was also studied. IgG anti-laminin at 2 x 10(-7)M had a highly significant stimulatory effect on PRL release after 3 and 5 hr of incubation, as compared to IgG from normal rabbit serum and medium alone used as controls. No changes on the release of LH and FSH were detected. These results suggest that laminin plays a physiologically significant inhibitory role on PRL release at the pituitary level in vitro.

Antibodies to laminin and immunohistochemical localization of laminin in chronic chagasic cardiomyopathy: a review.

Antibodies against laminin were determined by ELISA in forty six patients suffering from Chagas' disease and twenty healthy persons (control group). The patients were divided into three groups according to the severity of clinical, electrocardiographic and echocardiographic studies. Histologic, ultrastructural and immunohistochemical studies were made of endomyocardial biopsy specimens from 10 of these patients with chronic Chagasic cardiomyopathy. Antibodies to laminin were detected in 50% of the patients in each of the three groups. However analysis of the data did not allow us to determine any significant correlation among the severity of the different clinical and non-invasive studies and the level of circulating antibodies to laminin. The highest titers of antilaminin antibodies were detected in the group with severe cardiological alterations (37% of the patients). Histological and electron microscopic observation of myocardial biopsies disclosed marked thickening of the basement membranes of the myocytes, endothelial cells and vascular smooth muscle cells. Light (peroxidase-labeled antibodies) and electron (gold-conjugated antibody) microscopic immunohistochemical methods revealed a positive reaction for laminin in these thickened basement membranes. This thickening may develop as a consequence of: a) an immunologic reaction which is triggered by the presence of a laminin-like molecule on the surfaces of T. cruzi amastigotes and trypomastigotes; b) an immunologic response to direct injury of basement membranes causing some of their components to become antigenic; c) myocardial fibrosis, with synthesis of new connective tissue components, and d) a combination of the preceding factors. The relationship of these changes to antilaminin antibodies remains unclear.(ABSTRACT TRUNCATED AT 250 WORDS)

[Integrins: a family of cell adhesion receptors]. / Las integrinas: una familia de receptores de adhesión celular.

Integrins are a family of cell adhesion molecules (CAM's) that mediate the communication between the intracellular and the extracellular compartments. The growing interest in CAM's is due to the essential role they play in cell-cell and cell-matrix recognition processes. These receptors are formed by a non-covalently associated glycoprotein complex of two distinct polypeptide chains, called, alpha and beta. The association of different subunits results in the formation of, at least, 16 different integrins that provide cells with a great versatility in their adhesion properties. An integrin molecule comprises a cytoplasmic domain that interacts with the cytoskeleton, a transmembranous domain and an extracellular domain that binds to one or more ligands. beta 1, beta 2 and beta 3, are the best characterized integrin subfamilies; they are expressed, in different amounts, in epithelial and endothelial cells, leukocytes, fibroblasts and platelets. b1 integrins are essentially involved in cell-extracellular matrix interactions and beta 2 subfamily in leukocyte-leukocyte and leukocyte-endothelial cell communications. The integrin subfamily beta 3 mediates the adhesion of platelets with fibrinogen and other ligands. During embryonic development, integrins in association with other CAM's, play an essential role in cell migration and morphogenesis. Moreover, in processes like inflammation, wound healing and thrombosis, integrins and other CAM's mediate the interactions among the injured tissue and circulating cells. In two genetic diseases like the leukocyte adhesion deficiency and the Glanzmann's thrombasthenia an impairment in leukocyte-endothelial cell interactions and platelet aggregation is detected, due to deficiencies or abnormalities in beta 2 or beta 3 integrin subfamilies, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Las integrinas: una familia de receptores de adhesión celular. / [Integrins: a family of cell adhesion receptors]

Integrins are a family of cell adhesion molecules (CAMs) that mediate the communication between the intracellular and the extracellular compartments. The growing interest in CAMs is due to the essential role they play in cell-cell and cell-matrix recognition processes. These receptors are formed by a non-covalently associated glycoprotein complex of two distinct polypeptide chains, called, alpha and beta. The association of different subunits results in the formation of, at least, 16 different integrins that provide cells with a great versatility in their adhesion properties. An integrin molecule comprises a cytoplasmic domain that interacts with the cytoskeleton, a transmembranous domain and an extracellular domain that binds to one or more ligands. beta 1, beta 2 and beta 3, are the best characterized integrin subfamilies; they are expressed, in different amounts, in epithelial and endothelial cells, leukocytes, fibroblasts and platelets. b1 integrins are essentially involved in cell-extracellular matrix interactions and beta 2 subfamily in leukocyte-leukocyte and leukocyte-endothelial cell communications. The integrin subfamily beta 3 mediates the adhesion of platelets with fibrinogen and other ligands. During embryonic development, integrins in association with other CAMs, play an essential role in cell migration and morphogenesis. Moreover, in processes like inflammation, wound healing and thrombosis, integrins and other CAMs mediate the interactions among the injured tissue and circulating cells. In two genetic diseases like the leukocyte adhesion deficiency and the Glanzmanns thrombasthenia an impairment in leukocyte-endothelial cell interactions and platelet aggregation is detected, due to deficiencies or abnormalities in beta 2 or beta 3 integrin subfamilies, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Antilaminin IgG triggers the murine atria phosphoinositide hydrolysis through muscarinic receptor stimulation.

Induction of polyphosphoinositide hydrolysis in cardiac tissue by specific recognition of laminin by antilaminin IgG was assayed. BALB/c mice atria were labelled with the myo-[3H]-inositol precursor and inositol phosphate production was measured in the presence and absence of antilaminin and normal IgG. Antilaminin IgG but not normal IgG specifically increased phosphoinositide (PI) turnover. This increment was blocked by the muscarinic cholinergic antagonist atropine and mimicked by the cholinergic agonist carbachol. The phospholipase C inhibitor diphenylcarbamate (NCDC) also antagonized the stimulatory action of antilaminin IgG on PI turnover. By using an immunofluorescence technique, antilaminin IgG reacted with myocardial cell basement membranes. This antibody fixation was not blocked by atropine. These data suggest that antilaminin IgG specifically recognized myocardial laminin molecules and activated PI turnover through cholinergic stimulation. Even though laminin and cholinergic receptors are different, they probably share common signal transduction systems.

Testicular lesions and lymphocyte subpopulations in rats immunized with a soluble fraction of testicular homogenate.

A soluble fraction obtained from a testicular homogenate by precipitation with ammonium sulphate (ASPM) was emulsified with Freund's complete adjuvant (CFA) and injected into Wistar rats. At 50 days after the first immunization (total of three injections) the animals had developed moderate and multifocal testicular damage, characterized mainly by sloughing of the seminiferous epithelium. A delayed-type hypersensitivity response and circulating antibodies to ASPM were detected at different times with maximum levels at 50 days. The addition of Bordetella pertussis to the immunization did not increase the severity of the lesion but augmented the cellular and humoral immune response to ASPM. The phenotypic characterization of cells present in the lymph nodes draining from the site of immunization in animals injected with CFA alone (control group) revealed an increase in CD8+ T-cells and a low CD4/CD8 ratio. Conversely, rats immunized with CFA plus ASPM (experimental group) exhibited testicular damage and showed a significant decrease in CD8+ cells with a normal CD4/CD8 ratio. In conclusion, rats immunized with a testicular antigen developed focal aspermatogenic lesions and a concomitant specific immune response as well as lymph-node cell variations focused apparently on the CD8+ T-cell subpopulation.

Antilaminin IgG binds and interacts with cardiac cholinergic receptors.

Antilaminin IgG bound to cholinergic muscarinic receptors of normal mice heart and simulated the biological effect of a cholinergic agonist. Antilaminin IgG interfered with the binding of the radiolabelled muscarinic antagonist, (-)-[3H]quinuclidinyl benzilate, in a noncompetitive fashion. The interaction of antilaminin IgG with the muscarinic cholinergic receptor increased production of cGMP and decreased production of cAMP. Antilaminin IgG also decreased the contractile tension of mouse atria. Both the mechanical and enzymatic effect of antilaminin IgG required the activation of the muscarinic cholinergic system because they were blunted by atropine and mimicked by acetylcholine.

Antigenicity of basement membrane fractions obtained from rat seminiferous tubules.

A noncollagenous fraction of basement membrane (D-STBM) obtained from rat testes was submitted to sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis (SDS-PAGE), and eight well-defined bands were detected. A cross-reaction with an antiserum against laminin was revealed by immunoblotting in five bands, with molecular weights ranging from 54 to 64 kDa. No further resolution of these components could be obtained by size exclusion and ionic exchange chromatography. Fifty-two percent of the rats immunized with D-STBM and adjuvants developed a mild multifocal damage of the testis. The lesions were characterized by foci of seminiferous tubules with different degrees of sloughing and/or atrophy of the germinal epithelium. Giant multinucleated cells were frequently seen, and mild interstitial mononuclear cell infiltrates were also detected. By immunofluorescence, deposits of rat IgG with a faint discontinuous linear pattern were observed along the walls of the seminiferous tubules. Circulating antibodies to D-STBM were detected by ELISA in 100% of the rats, whereas in a cross-reaction with laminin antibodies were detected in only 63%. All rats studied revealed a positive delayed type of hypersensitivity (DTH) response to D-STBM. None of the control rats injected with saline and adjuvants presented circulating antibodies to D-STBM or laminin or a positive DTH reaction to D-STBM. Some control group rats (10%) revealed few isolated seminiferous tubules with some degree of sloughing of the germinal epithelium.

Negative inotropic activity of antilaminin IgG: participation of cholinergic mechanisms.

1. Antilaminin IgG decreased the dF/dt of mouse isolated atria and inhibited the mechanical effect of acetylcholine in a non-competitive fashion. 2. Inhibitors of nicotinic and muscarinic cholinoceptors impaired the negative inotropic action of antilaminin IgG in mouse isolated atria. Hemicholinium and tetrodotoxin also reduced the response while the antihistamine, pyrilamine was without effect. 3. These results suggest that antilaminin IgG modulates cholinergic function in mouse isolated atria. Possible mechanisms are discussed.

[Experimental autoimmune orchitis]. / Orquitis autoinmune experimental.

Experimental autoimmune orchitis (EAO) has been extensively studied in spite of which its pathogenic mechanisms are still poorly understood. It has been mostly induced in guinea pigs using spermatozoa or a testicular homogenate plus adjuvants. Initially, the aim of our work was to establish if non-spermatic antigens, such as extracellular components of the walls of seminiferous tubules, were able to induce an autoimmune orchitis. For this purpose, we obtained from rat testes: a) a preparation rich in basement membranes of seminiferous tubules (STBM) and b) a soluble fraction of STBM, non-related to collagen (D-STBM), presenting common antigenic determinants with laminin, the main non-collagen glycoprotein of basement membranes. Fifty per cent of rats immunized with STBM, D-STBM or a murine laminin, developed a multifocal and moderate damage of the testes characterized by mild interstitial cell infiltrates, alterations of the basement membranes of seminiferous tubules and Sertoli cells, sloughing of the germinal epithelium and tubular atrophy. Circulating antibodies and a specific cellular immune response were also detected. Moreover, rats passively injected with an heterologous anti-D-STBM serum developed a similar testicular lesion and showed Ig deposits on the basement membranes of seminiferous tubules. In relation to the pathogenic mechanisms of EAO, we studied the variations of T and B cell populations, at the immunization draining lymph nodes, during the development of orchitis. A severe EAO was induced in Wistar rats by immunization with an homologous testes homogenate plus adjuvants.(ABSTRACT TRUNCATED AT 250 WORDS)