Influence of gonadal hormones on endocrine activity of gonadotroph cells in the adenohypophysis of male lambs during the postnatal transition to puberty

Using histomorphological and functional criteria we describe the feedback mechanisms which could play a role in the regulation of the gonadotrophic axis during the postnatal transition to puberty in male lambs. The working hypothesis was that the testicular factors change the peripheral levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by influencing the synthesis rate and storage of LH and FSH in adenohypophyseal gonadotroph cells of weanling and weaned pubertal lambs. The examination was made in (i) 9-week-old infantiles, suckling lambs undergoing weaning, testis-intact (TEI) and orchidectomised (ORCHX) at the 6th week of age, and (ii) 16-week-old pubertal lambs TEI and ORCHX at the 12th week of age (n=5 per group). Changes in gonadotrophs were assayed with hybridohistochemistry, immunohistochemistry and radioimmunoassay. The percentage of the adenohypophyseal area (PA) occupied by cells containing LHβ-mRNA and FSHβ-mRNA and peripheral levels of both gonadotrophins were lower (P<0.01) in the 16-week-old TEI lambs in comparison with the 9-week-old ones. The PA occupied by cells immunoreactive for LHβ was lower (P<0.01), whereas in the case of FSH was greater (P<0.001) in the 16-week-old lambs. After orchidectomy the PA occupied by gonadotrophs stained for LHβ-mRNA was greater (P<0.01) in 16-week-old lambs. The PA occupied by LHβ-labelled cells was lower (P<0.05) in the 9-week-old ORCHX lambs, whereas in 16-week-old ones was higher (P<0.05) in comparison with the TEI lambs. The circulating LH was greater (P<0.01) in the ORCHX 9- and 16-week-old lambs compared to the TEI ones. The PA occupied by cells containing FSHβ-mRNA and the plasma FSH concentration were greater (P<0.001) after orchidectomy in lambs from both age stages. The PA occupied by FSHβ-labelled cells was greater (P<0.01) in the 9-week-old ORCHX lambs, whereas in 16-week-old ones was lower (P<0.05) compared to the lambs from TEI groups. In conclusion, in infantile lambs testicular factors may play inhibitory role in regulating FSH synthesis rate, storage and release in contrast to the stimulatory role in regulating LH storage reflected by the inhibitory role in regulating LH release. In lambs at the beginning of puberty, testicular factors may play inhibitory role in regulating LH synthesis rate, storage and release in contrast to the stimulatory role in regulating FSH storage reflected by the inhibitory role in regulating FSH synthesis rate and release. The effects of testicular hormones on the gonadotrophin storage, i.e. releasable pools in adenohypophyseal cells, are specific for both LH and FSH in lambs during the postnatal transition to puberty. Thus, the initiation of puberty in male sheep is a function of change of the inhibitory role of gonadal factors in regulating FSH storage to the stimulatory one and the stimulatory role of gonadal factors in regulating LH storage to the inhibitory one.     

Aromatization and antioxidant capacity in the testis of seasonally breeding bank voles: Effects of LH, PRL and IGF-I

Aromatization and antioxidant strategies in the male gonads are important processes, which are involved in control of normal fertility. The objective of this study was to show whether luteinizing hormone (LH), prolactin (PRL), and insulin-like growth factor-I (IGF-I) as well as the length of photoperiod are able to exert an effect on aromatase expression, steroid hormone levels, and antioxidant concentrations in testes of bank voles, seasonally breeding rodents. Mature bank voles that were kept under short light cycles or long light cycles served as the animal model. Testicular sections were used for immunohistochemical visualization of aromatase expression, whereas testicular homogenates were used for radioimmunological measurement of steroids, biochemical determination of superoxide dismutase activity, total antioxidant status (TAS) and protein content. In the testes of hormone-treated voles a stronger immunostaining for aromatase was concurrent with the increase in testosterone and estradiol levels, and total antioxidant status compared with the controls. In contrast, there was a decrease in superoxide dismutase (SOD) activity. The strongest effect on aromatase immunoexpression and steroid hormone levels was detected after combined doses of LH and IGF-I, indicating a stimulatory role of these hormones on estrogen synthesis in the bank vole. An increase in total antioxidant status in testes of hormone-treated bank voles suggests the presence of testicular defense, whereas a decrease in superoxide dismutase activity indicates a protective role of administered hormones against toxic oxygen radicals. The present study also demonstrates a significant, photoperiod-dependent relationship between aromatization and antioxidant capacity in the testis of the bank vole.     

Influence of sodium fluoride and caffeine on the concentration of fluoride ions, glucose, and urea in blood serum and activity of protein metabolism enzymes in rat liver

The aim of the study was examining the effect of fluoride ions and caffeine administration on glucose and urea concentration in blood serum and the activity of protein metabolism enzymes and selected enzymes of the urea cycle in rat liver. The study was carried out using 18 male Sprague-Daowley rats (4.5 mo old). Rats were divided into three groups. Group I received distilled water ad libitum. Group II received 4.9 mg F⁻/kg body mass/d of sodium fluoride in the water, and group III received sodium fluoride (in the above-mentioned dose) and 3 mg/kg body mass/d of caffeine in the water. After 50 d, the rats were anesthetized with thiopental and fluoride ions, glucose, and urea concentration in blood serum were determined. Also determined were the activities of aspartate aminotransferase, alanine aminotransferase glutamate dehydrogenase, ornithine carbamoylotransferase and arginase in liver homogenates. Liver was taken for pathomorphological examinations. The applied doses of F⁻ (4.9 mg/kg body mass/d) and F⁻+ caffeine (4.9 mg F⁻/kg body mass/d+3 mg caffeine/kg body mass/d) resulted in a statistically significant increase of fluoride ion concentration in blood serum, a slight increase of the glucose concentration, and no changes in the concentration of urea in blood serum. This might testify to the absence of kidney lesions for the applied concentrations of F⁻. No change in the functioning of hepatocytes was observed; however, slight disturbances have been noted in the functioning of the liver, connected with the activation of urea cycle, increase of arginase activity, and accumulation of F⁻ in this organ. There was no observed significant influence of caffeine supplementation on the obtained results.     

Human bone marrow stroma cells display certain neural characteristics and integrate in the subventricular compartment after injection into the liquor system

Because the neural differentiation capacity of bone marrow stromal cells (BMSCs) is still a matter of controversial debate, we performed a thorough investigation into the differentiation capacity of human BMSCs and examined their therapeutic potency. BMSCs were isolated from the femur and kept in cell cultures with various cultivation protocols being applied. In standard culture conditions using a fetal calf serum-enriched medium, while not exhibiting a neural phenotype, the majority of cells expressed a variety of neuronal marker proteins as well as the astrocyte marker GFAP. Only a minority of stem cells expressed nestin, a marker for neural precursor cells. Cultivation in serum-free medium supplemented with specific growth factors resulted in a markedly higher percentage of nestin-positive cells. To establish the therapeutic potency of bone marrow-derived cells, the synthesis of neurotrophic factors such as NGF, BDNF and GDNF was analyzed under non-stimulating standard culture conditions as well as after a neural selection procedure. The therapeutic potency of BMSCs was further examined with regard to their migratory potential in vitro and after transplantation in vivo. After stereotactic engraftment into the lateral ventricle of adult rats, mesenchymal stem cells were seen to adhere to the ependymocytes and cells of the choroids plexus. Afterwards grafted cells passed through the ependymal barrier, locating in the subventricular space. Their BMSCs took up a close host graft interaction without any degenerative influence on the host cells. Furthermore, there was morphological as well as immunohistochemical evidence for a transdifferentiation within the host tissue. In addition, BMSCs could be efficiently transduced using a third-generation adenoviral vector, indicating their potential feasibility for a gene-therapeutic option.     

Proliferating cell nuclear antigen (PCNA) expression in pituitary adenomas: relationship to the endocrine phenotype of adenoma

The expression of proliferating cell nuclear antigen (PCNA) correlates to cell proliferation and for this reason it is commonly considered as one of proliferation markers. Since proliferation rate is an important factor determining the tumor aggressiveness, the evaluation of PCNA index (the percentage of PCNA-immunopositive nuclei in the investigated tumor sample) is suggested as useful in predicting pituitary adenoma outcome. Seventy three unselected, surgically removed pituitary adenomas were immunostained with antibodies against the pituitary hormones or their subunits and against the proliferating cell nuclear antigen (PCNA). The highest PCNA index was found in ACTH-immunopositive tumors without the manifestation of the Cushing's disease ("silent" corticotropinomas). This value was significantly different in comparison to other adenoma subtypes including corticotropinomas manifesting themselves by Cushing's disease. The lowest PCNA index was noticed in monohormonal GH-secreting tumors. The adenomas which express more than one hormone (plurihormonal adenomas) seem to have a higher PCNA indices than monohormonal ones; the difference was significant in the case of mono- and plurihormonal prolactinomas. The recurrent tumors presented a higher mean PCNA index as compared to the primary tumors, although the difference was significant only in the case of prolactinomas. These findings suggest that the proliferative potential of pituitary adenomas is related to the tumor recurrence and hormone expression.     

Immunocytochemical characterization of two thyroid medullary carcinoma cell linesin vitro

Summary The immunocytochemical characterization of cell lines originating from thyroid medullary carcinoma, i.e. human TT cells and rat rMTC 6-23 cells, was undertaken. The immunocytochemical studies were supplemented by ultrastructural studies, including ultrastructural immunocytochemistry, and by radioimmunological estimation of calcitonin secretion to the medium. In rMTC 6-23 cells (subcultures 24 to 30), no hormone presence was demonstrated immunocytochemically, which corresponded to the absence of secretory granules at the ultrastructural level. Of various proteins sought, only neuron-specific enolase could be demonstrated. Nevertheless, the cells secreted calcitonin into the medium. TT cells (passages 145 to 160) produced secretory granules. The granules contained calcitonin, calcitonin gene-related peptide, somatostatin, neurotensin, met-enkephalin, leu-enkephalin, gastrin releasing peptide, parathyroid hormone-related protein, functional proteins of the chromogranin group and synaptophysin. Other functional proteins found in the cytosol of TT cells included non-specific enolase, calbindin and tyrosine hydroxylase. Receptor for calcitriol was localized in the cell nucleus. Marker proteins were localized in the cytosol (carcinoembryonic antigen) and in the cell skeleton (-tubulin, cytokeratin). Following changes in ionized calcium levels in the medium, changes in calcitonin secretion and in immunocytochemical detectability of some hormones and functional proteins were observed. TT cells demonstrated the expression of numerous hormones and functional proteins associated with calcitonin secretion. Further, the cells in their ultrastructure, immunocytochemical and secretory characteristics, resemble more closely normal parafollicular cells of the thyroid and, in our opinion, represent a more appropriate model for functional studies.     

Rotifer occurrence in relation to age,depth and trophic state of quarry lakes

An effect of age of quarry lakes on rotifer abundance and species composition has been evaluated. Rotifers occurred in all lakes under study. They were even found in the youngest (2 years of age) one, Rogonica 4, but both rotifer density and species richness were low there. Rotifer communities of much higher density and species diversity were noted in lakes only 4–6 years older. Lakes of over 30 years of age were strongly differentiated in rotifer numbers and species structure. In general, age of quarry lakes has an impact on rotifer communities only at the very beginning of the process of colonization. Several years later other factors become more important, e.g., depth or trophic state of the lakes.