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-, β- 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/β-catenin colocalization (confocal microscopy) and increased pY654 β-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.

Death receptor and mitochondrial pathways are involved in germ cell apoptosis in an experimental model of autoimmune orchitis

BACKGROUND

Studies on experimental autoimmune orchitis (EAO) have helped to elucidate immunological mechanisms involved in testicular damage. We previously demonstrated that EAO is characterized by lymphomononuclear cell infiltrates and apoptosis of spermatocytes and spermatids expressing Fas and TNFR1. The aim of this work was to characterize the pathways involved in germ cell apoptosis in EAO and to determine the involvement of the Bcl-2 protein family in this process.

METHODS AND RESULTS

EAO was induced in rats by immunization with testicular homogenate (TH) and adjuvants, whereas control (C) rats were injected with saline solution and adjuvants. Testis of EAO rats showed procaspase 8 cleavage products (western blot) with high caspase 8 activity. Cytochrome c content increased in the cytosol and decreased in the mitochondrial fraction of testis from EAO rats compared with C, concomitant with increased caspase 9 activity. Bax was mainly expressed in spermatocytes and spermatids and Bcl-2 in basal germ cells (immunohistochemistry). Baxbeta isoform content increased in EAO rat testis compared with C, whereas content of Baxalpha remained unchanged (western blot). However, Baxalpha content decreased in the cytosol and increased in the mitochondrial and endoplasmic reticulum (ER)-enriched fractions of testis from EAO rats compared with C (western blot). Bcl-2 content also increased in the testes of EAO rats.

CONCLUSIONS

Our results demonstrated that extrinsic, mitochondrial and possibly ER pathways are inducers of germ cell apoptosis in EAO and that Bax and Bcl-2 proteins modulate this process.

Supplementation patterns in marathon runners

The purpose of the present investigation was to study the use of supplements in a large group of endurance runners (no. = 347) who had participated in the 1987 Los Angeles Marathon. Three-day dietary records were analyzed for nutrient content and supplement usage. The runners' supplementation patterns with respect to demographics, dietary quality, training habits, and race performance were investigated. In general, no significant associations were found between supplement use and the aforementioned variables. Use of supplements, especially vitamins C and E, calcium, and zinc, increased with age (p less than .05). Daily use of at least one type of supplement was reported by 29% of the runners; 48% reported use of at least one type of supplement within the 3-day period.

Nutrient intake of marathon runners

Three-day food records from a large group of marathon runners (291 men, 56 women) were analyzed and compared to various standards of dietary quality. Intake by the runners exceeded two-thirds of the Recommended Dietary Allowance for all nutrients except vitamin D and zinc in female runners. Energy and nutrient intake levels in the marathon runners were higher than those of the general U.S. population except for total fat, vitamin B-12, and zinc in both men and women and sodium in men. In general, runners consumed better diets than the general population. However, both caloric intake and percent energy as carbohydrate were lower than recommended for individuals engaging in endurance exercise. The need for professional help in planning high-carbohydrate diets for runners is indicated. Increasing amounts of training were not associated with significant increases in nutrient densities across three activity categories within this group of runners. However, more than 75% of the runners perceived their diets to be much improved after they began regular training (men 8.2 +/- 0.3 years of running experience, women 6.7 +/- 0.6). Together, these data suggest that regular moderate-to-heavy endurance exercise is associated with a better quantity and quality of nutrient intake than that found in the general population, which may in part be related to the adoption of such exercise by previously sedentary individuals.