The significance of insulin, insulin-like growth factor I (IGF-I) and glucocorticoids to the early mammalian embryo is clear in that they are key regulators of both mitogenic and metabolic effects during development. In the present study, the temporal sequence of expression of the respective receptor proteins was investigated for the first time in the developing rat utero-embryonic unit between conception and day 12 of gestation using immunocytochemistry. Insulin, IGF-I and glucocorticoid receptor were expressed in embryonic tissues after the start of implantation, and were co-localized in the primary ectoderm, extraembryonic ectoderm as well as in the ectoplacental cone. The parietal endoderm was devoid of glucocorticoid receptor staining, whereas IGF-I receptor was absent in visceral endoderm. After completion of basic organogenesis, the neural tube, notochord, otic placode, Wolffian duct, mesonephros and intestinal tube expressed insulin, IGF-I and glucocorticoid receptor. The glucocorticoid receptor was not expressed in heart tube and dorsal aortae. Considerable amounts of insulin receptor were detected in trophoblast-derived giant cells. In the uterus, luminal epithelium, endometrial stromal and myometrial smooth muscle cells immunoreacted with antisera against insulin, IGF-I and glucocorticoid receptor. Endometrial glands remained negative for the glucocorticoid receptor throughout the gestational period investigated. Uterine hormone receptor expression reached a peak at days 4 and 5 of gestation in endometrial stromal cells and decidua, respectively. In conclusion, the demonstrated ontogenetic pattern of insulin, IGF-I and glucocorticoid receptor expression indicates the potential sites of biological action of the respective ligands, providing supportive evidence for their critical importance during the course of embryogenesis in rats.

The aim of this study was to determine the cadmium (Cd)-induced functional and structural changes in gastric parietal cells of male rats exposed to high Cd for 30 d. In the present study, control animals were fed with normal food and tap water; the remaining animals received Cd (15 ppm CdCl2) in drinking water for the same period. Receiving Cd for 30 d increased the mean blood Cd level, the mean tissue Cd content, and the mean blood pressure (p < 0.01, p < 0.001, p < 0.01, respectively). The basal acid output fell; however, the increases in stimulated acid output were not statistically significant. Light and electron microscopic examination revealed respectively that (1) Cd decreases the mean parietal cell number per unit from the control value of 23.46 +/- 3.84 to 19.46 +/- 2.12 (p < 0.05) and it affected preferentially the cells located at the distal half of the zymogenic unit and (2) in parietal cells, the Cd-induced alterations were characterized with swollen canalicular profiles, broken-down tubulovesicles, or degenerated mitochondria. We concluded that Cd augments the elimination rate of parietal cells by increasing the alteration rate and reduced basal acid output can be explained easily with the loss of parietal cell population.