Biomedical subjects

Yvonne Ridderstråle

Publications and source records attributed to Yvonne Ridderstråle.

6 recordsLinked to original sources

PubMed2006

Embryonic exposure to o,p'-DDT causes eggshell thinning and altered shell gland carbonic anhydrase expression in the domestic hen.

The mechanism for contaminant-induced eggshell thinning in wild birds remains to be clarified. It is generally assumed, however, that it results from exposure of the adult laying female. We have reported that embryonic exposure to the synthetic estrogen ethynylestradiol (EE2) results in eggshell thinning in the domestic hen. The objective of this study was to investigate whether eggshell thinning can be induced following in ovo exposure to a bioaccumulating estrogenic environmental contaminant, o,p'-DDT. Ethynylestradiol was used as a positive control. Domestic hens exposed in ovo to o,p'-DDT (37 or 75 microg/g egg) or EE2 (60 ng/g egg) laid eggs with thinner shells than the control birds. The hens from these exposure groups also had a significantly reduced frequency of shell gland capillaries with carbonic anhydrase (CA) activity, a key enzyme in eggshell formation. The decreased number of capillaries with CA activity suggests that a developmentally induced disruption of CA expression in the shell gland was involved in the eggshell thinning found in this study. Egg laying was not affected in hens exposed embryonically to 37 or 75 microg o,p'-DDT/g egg, whereas it was inhibited in hens exposed to higher doses. Decreased lengths of the left oviduct and its infundibulum were seen after embryonic treatment with o,p'-DDT or EE2. In addition, o,p'-DDT exposure resulted in right oviduct retention. The results support our hypothesis that eggshell thinning in avian wildlife can result from a functional malformation in the shell gland, induced by embryonic exposure to estrogenic substances.

Animals↗

PubMed2004

Effects of intracerebroventricular infusion of genistein on gonadotrophin subunit mRNA and immunoreactivity of gonadotrophins and oestrogen receptor-alpha in the pituitary cells of the anoestrous ewe.

The present study was designed to demonstrate whether genistein, a synthetic phytoestrogen, infused into the third ventricle of the brain could affect the gonadotrophic cells regarding the presence of oestrogen receptor-alpha immunoreactivity and gonadotrophin subunit mRNA hybridising reaction in the ewe. Ewes (n=7), aged 2 years, in early anoestrous season were infused with Ringer-Locke solution (control, n=3) or 10 microg/100 microl/h of genistein (n=4) into the third ventricle over a 5 h period and slaughtered the following morning. Immunoreactivity of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and oestrogen receptor-alpha (ERalpha) was determined in the adenohypophysis by immunohistochemistry using antibodies raised against LHbeta, FSHbeta, and ERalpha. Messenger RNA analyses were performed by non-isotope in situ hybridisation using sense and antisense riboprobes produced from beta subunits of LH and FSH cDNA clones. Computer image analysis was used to determine the percent of cells exhibiting immunohistochemical and/or hybridising reaction. It was found that in ewes infused with genistein, the percentage of LH-positive cells and the density of immunoreactive-LHbeta material decreased significantly (P<or=0.001), but the percentage of mRNA LHbeta-expressing cells and the intensity of the hybridisation signal increased significantly (P<or=0.001), compared to the vehicle-infused animals. The genistein infusions had no effect on the immunoreactivity of FSH cells or on the expression of mRNA for FSHbeta. The percentage of ERalpha-positive cells increased significantly after genistein infusions (P<or=0.001) and this increase was significant in the LH but not in FSH cells (P<or=0.001). In conclusion, we suggest that genistein can stimulate the expression of immunoreactive ERalpha in the pituitary LH-cells but not in FSH-cells and change the endocrine activity of LH-producing cells of anoestral ewes.

Anestrus↗

PubMed2004

Carbonic anhydrase in mouse testis and epididymis; transfer of isozyme IV to spermatozoa during passage.

Spermatozoa are subjected to major changes as they pass through the epididymal duct. The aim of the present study was to describe the distribution of carbonic anhydrase (CA) in the mouse testis and epididymis using a histochemical technique showing total catalytic activity, in combination with immunohistochemistry for the two important isoforms CAs II and IV. By comparing normal mice with CA II-deficient mice, we were able to study membrane-bound CA without influence from the ubiquitous cytoplasmic CA II. Spermatozoa, when studied in both the scanning electron and light microscope, were found to pickup membrane-bound CA IV during their passage through the epididymal duct. The transfer appeared to take place in the proximal part of the corpus, where the apical membrane and vesicles of principal cells were richly supplied with CA IV. In addition to CA IV, another membrane-bound isozyme was located in basolateral membranes of principal cells. Cytoplasmic CA II was found in varying amounts in apical/narrow cells and principal cells of the corpus in control animals. The significance of CA for pH-regulating processes vital for sperm storage and motility is discussed. A function in HCO3- transport during sperm capacitation at fertilization is suggested for the CA IV found in spermatozoa.

Animals↗

PubMed2002

Reproductive impairment in Japanese quail (Coturnix japonica) after in ovo exposure to o,p'-DDT.

We have previously described various effects in adult Japanese quail consequent on treatment with oestrogenic compounds in ovo. In the present study, the environmental contaminant o,p'-DDT [1-(2-chlorophenyl)-1-(4-chlorophenyl)-2,2,2-trichloroethane] was administered to quail eggs to further evaluate test endpoints for oestrogenic effects related to reproduction in the Japanese quail. Exposure to 2 mg o,p'-DDT/egg (150 micro g/g egg) resulted in impaired sexual behaviour, reduced cloacal gland area and lowered plasma testosterone concentration in males. Females displayed oviductal abnormalities, including retained right oviduct, decreased length of left oviduct, alterations in shell gland morphology and disrupted distribution of carbonic anhydrase in the shell gland. Egg laying was severely impaired. Consequently, a number of endpoints in adult quail may be useful for demonstrating an oestrogen-like mode of action by environmental contaminants during embryonic development.

Animals↗

PubMed2002

Thyroid gland function in ovariectomized ewes exposed to phytoestrogens.

Phytoestrogens are by definition plant-derived substances that are able to activate the mammalian oestrogen receptors. We examined the possible effects of phytoestrogens on the secretion of thyroid hormones as well as on the immunoreactivity to oestrogen receptor alpha (ER alpha) in the thyroid glands of ovariectomized ewes. Eight ovariectomized ewes were fed 3.5 kg of 100% red clover silage for 14 days. Blood samples were collected before and on day 14 of exposure to phytoestrogens. After 5 months, four of the ewes were re-exposed to red clover silage as described above and the other four served as controls. Blood samples were collected as above. All ewes were slaughtered at the end of the experiment and the thyroid glands were weighed and examined for macroscopical changes. Tissue samples were taken for immunohistochemistry and image analysis. Ewes exposed to red clover silage had significantly higher plasma concentrations of total T(3) and free T(3) than ewes fed hay. The cross-section area of thyroid follicles tended to be larger in ewes fed red clover silage than in the control animals. ER alpha immunoreactivity was stronger in thyroid glands from ewes exposed to phytoestrogens than in ewes fed hay. In conclusion, daily ingestion of 81-95 mg phytoestrogens per kg body weight for 14 days stimulated secretion of thyroid hormones and tended to increase follicle size and ER alpha immunoreactivity of thyroid glands of ovariectomized ewes.

Animals↗

PubMed2002

Development of sperm storage tubules in the quail during sexual maturation.

The development of the utero-vaginal sperm storage tubules (SST) in the quail during sexual maturation was studied using light microscopy and image analysis. SST development starts at around 28 days with low columnar cells, 10.9 +/- 0.7 microm high, found at the base of mucosal folds in the distal uterus. Seven days later, small bud-like invaginations consisting of columnar, 16.4 +/- 1.1 microm high cells with basal nuclei were found in this region. An extremely rapid growth of the oviduct occurred at approximately 40-42 days of age with considerable variation in oviductal length between birds, coefficient of variation (CV) 64.8% and 66.2%, respectively. Two of these birds had SST containing spermatozoa but were not laying. At 49 days, oviductal length was 24 +/- 0.5 cm (CV 2.0%), and all birds had functional SST with spermatozoa and had started to lay. Mature SST consist of columnar, nonciliated cells, 19.8 +/- 0.7 microm high. Although development of SST in the quail, to a large extent, coincides with the development of the rest of the oviduct, the present findings suggest that utero-vaginal sperm storage is possible before the complete maturation of the oviduct and subsequent onset of lay.

Animals↗