No abstract

Autoradiography and angiotensin (Ang) II receptor binding studies showed that all parts of the bovine placenta and fetal membranes contained high densities of Ang II receptors throughout gestation. The receptors were predominantly subtype 2 (AT2) receptors in the fetal and subtype 1 (AT1) receptors in the maternal compartment. In the allantoamnionic membrane, Ang II receptors were evenly distributed in the mesenchymal tissue, with the highest expression around the few arteries. In the intercotyledonary and cotyledonary allantochorionic membrane, AT2 receptors as well as the less-expressed AT1 receptors were located on mesenchymal cells, especially adjacent to the allantoic endoderm, trophoblast cell layer, and arteries. In the mesenchymal tissue of the placentome, Ang II receptors were mostly expressed at the main branches of the fetal villi of the cotyledons. In the maternal part of the placentome, mainly AT1 receptors but also low densities of AT2 receptors and non-AT1/non-AT2 Ang II binding sites were found close to the stalk and at the main branches of the maternal crypts. Autoradiography revealed no changes in the pattern of distribution of the Ang II receptors throughout gestation. It is suggested that Ang II has an effect on regulatory as well as growth processes in these tissues.

Angiotensin (Ang) II may modulate reproductive function in the bovine ovary. Therefore, expression and localization of a local ovarian renin-angiotensin system (RAS) were investigated by elucidating the influence of the estrus cycle, pregnancy, and the presence of follicular cysts. Receptor analysis and autoradiography were used to characterize and localize Ang II receptors. Cyclic variations in the density of ovarian Ang II receptors were found with a higher value in estrus than in diestrus. The density in ovaries with follicular cysts was in the same order of magnitude as in estrus. The Ang II receptor type 2 (AT(2)) dominated in all three groups. Autoradiography showed that the majority of antral follicles and follicular cysts had intense AT(2) receptor binding in the theca externa. Binding was less intense in the theca interna, whereas there was no binding in the granulosa layer. In the corpora lutea, the AT(2) receptor was dominant in the capsule and in connective tissue infoldings, whereas no binding was observed in the luteal tissue. The type 1 Ang II receptor (AT(1)) was dominant in the stroma and showed no cyclic changes. Angiotensin-converting enzyme (ACE) activity was detected in all aspirated follicular fluids and homogenates of ovarian tissue. Autoradiography showed that most of the ACE was localized on endothelial cells. Renin immunoreactivity was found in granulosa and thecal cells of antral follicles and in luteal cells. Furthermore, solitary cells in the stroma, presumably macrophages, displayed intense staining. Our finding of cyclic changes support the concept of an active and regulated RAS in the bovine ovary.

1. The aim of the present study was to characterize the angiotensin II (AngII) receptor subtypes in the porcine uterus and the variation of receptor densities and renin concentrations during gestation. 2. In myometrium from non-pregnant sows, the AngII receptors were almost exclusively AT2 receptors. During gestation, the AngII receptor density was decreased and the AT1 receptor became predominant in the last part of gestation as a result of a down-regulation of the AT2 receptor. 3. In the endometrium, the AT1 receptor was predominant both in non-pregnant sows and throughout gestation. The AngII receptor density was decreased during gestation as a consequence of down-regulation of the AT1 receptor. 4. The renin concentrations in the myometrium and endometrium of pregnant sows did not differ from those in non-pregnant animals. 5. The finding of enzymatically active renin and high densities of AngII receptors in the porcine uterus is in accordance with a functional renin-angiotensin system (RAS), which may be important for an increased vascular permeability and stimulated angiogenesis in early pregnancy and for contraction of the myometrial smooth muscle cells during parturition. The predominance of AT1 receptors in the endometrium of non-pregnant sows differs from an earlier finding in non-pregnant women, where AT2 receptors were predominant in the endometrium. This is in accordance with earlier studies, indicating species differences in the expression and possibly also the physiological roles of the RAS in reproductive tissues.

Although infection of pigs with Salmonella Typhimurium represents a serious problem, most studies on Salmonella infection have been carried out in other species. The purpose of the current study was to examine the route(s) of entry of Salmonella Typhimurium in pigs, using a jejunal loop model. The infection process was followed over 240 min using single to triple immunocytochemical detection of Salmonella and intestinal cell markers. Salmonella invasion was observed in both cytokeratin-18-positive and -negative cylindrical absorptive cells within 5-10 min. Subepithelial invasion of ordinary villi was consistently less marked than invasion of the subepithelial layer of Peyer's patches. Our results show that several epithelial cell types were invaded by Salmonella, and that Peyer's patches represent the main portal of entry in early Salmonella infection. Additionally, infection was associated with alterations in the keratin and F-actin cytoskeleton of intestinal epithelial cells, probably reflecting toxin-mediated actions. Such changes were confined to the proximal region of the jejunum, demonstrating a regional heterogeneity of intestinal epithelial cell responses to Salmonella infection.