Electronic Library of Scientific Literature
Volume 33 / No. 4 / 1999
J.Knopp, D.Jezova, M.Rusnak, I.Jaroscakova, R.Farkas, R.Kvetnansky
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlarska 3, 833 06 Bratislava, Slovakia
Objective. To reexamine the possible role of catecholamines and corticosterone in
the early period of liver regeneration after partial hepatectomy (PH) in conscious
cannulated rats under carefully controlled conditions which would allow to obtain reliable
information about sympathetic-adrenomedullary function after PH in the rat in vivo.
Methods. Plasma levels of catecholamines (epinephrine - EPI, norepinephrine - NE) were estimated by radioenzymatic assay and these of corticosterone by competitive protein binding assay. The total RNA was isolated from the adrenals and tyrosine hydroxylase (TH) mRNA expression was estimated by hybridisation with cDNA after Northern blot. The level of immunoreactive protein was measured by using a monoclonal antibody to rat TH, visualized by Western light chemiluminiscent detection system and analyzed by densitometry. The level of TH in adrenals was estimated with the aid of 3H-tyrosine and TH cofactor DL-6-methyl-5,6,7,8-tetrahydropterine and the formed radioactive water was measured by scintillation spectrometry.
Results. The plasma level of norepinephrine (NE), epinephrine (EPI) and corticosterone rapidly increased 20 min after PH or sham operation (laparotomy). Although the increase of plasma NE was about the same after both PH and laparotomy, that of EPI and corticosterone in PH rats was significantly higher as compared to the laparotomy. One hour after the surgery plasma NE levels in both groups decreased to the basal value and remained still unchanged 4 and 24 h later. At the interval of 4 h the plasma level of EPI and corticosterone in PH was higher than in laparotomized controls, but after 24 h the EPI levels returned to basal values. Adrenal tyrosine hydroxylase (TH) mRNA level was significantly elevated in both PH and laparotomized rats, however 24 h after the surgery they returned to the baseline. Adrenal TH immunoprotein levels and TH activity were significantly elevated in both groups 4 h after the surgery, while 24 h later they returned to the baseline in laparotomized rats but remained elevated in PH rats. Adrenal phenylethanolamine N-methyl-transferase (PNMT) mRNA levels were increased 4 h after both the PH and laparotomy and declined within 24 h.
Conclusions. The first peak of catecholamine and corticosterone levels might result from unspecific stressor associated with the surgery. These levels could be accompanied with the mechanism of the rat liver regeneration. Prolonged elevations of EPI found after PH seems to be specific for liver regeneration indicating that the rise in the adrenal TH mRNA appears to be translated into immunoreactive protein which further leads to the elevation of TH activity. These results contrast markedly with previous studies indicating that the regeneration is modulated predominantly by norepinephrine.
Key words: Partial hepatectomy - Catecholamines - Corticosterone - Tyrosine
hydroxylase (TH) mRNA - TH immunoreactive protein - TH level
ENDOCRINE REGULATIONS, Vol. 33, 145 - 153, 1999
Download full text in PDF format (169 kB)
E.L. Gregoraszczuk, J. Kolodziejczyk, J. Rzysa
Department of Animal Physiology, Institute of Zoology, Jagiellonian University, 30-060 Krakow, Poland and Department of Animal Physiology, Academy of Agriculture, Kraków, Poland
Objective. To study the mechanism of thyroid hormone action on the activity of
3beta-hydroxysteroid dehydrogenase in the porcine corpus luteum.
Methods. Pig ovaries were obtained from slaughterhouse animals. Luteal cells were isolated from mid-developing (5-7 days after ovulation) corpora lutea and incubated for 24 h with or without triiodothyronine. Trilostane, an inhibitor of 3 beta-HSD that blocks the conversion of pregnenolone to progesterone, was added to the medium in doses of 0, 0.1, 1, 10, and 100 micromol. Each treatment was performed in triplicate and each culture system was set up in triplicate. Progesterone concentrations in culture media were determined by radioimmunoassays.
Results. Trilostane in a dose of 100 microM significantly decreased the basal progesterone secretion from luteal cells by 26 % (P<0.05). However, such secretion was increased by triiodothyronine (T3) in a dose of 10-9 M. In addition, in T3-treated cells dose dependent inhibitory effect of trilostane on progesterone secretion was observed. Control cultures grown in control medium revealed a relatively weak 3 beta-HSD activity which, however, markedly increased after the addition of T3 to the culture medium. Trilostane remarkably decreased 3 beta-HSD activity in T3-stimulated cells.
Conclusion. It was found that T3 acts on luteal cell steroidogenesis via the activation of 3beta-hydroxysteroid dehydrogenase in these cells.
Keys words: Triiodothyronine - Corpus luteum - Progesterone - 3beta-hydroxysteroid dehydro-genase - Trilostane
Endocrine regulations, Vol. 33, 155 - 160, 1999
Download full text in PDF format (136 kB)
E. Potargowicz, W.Z. Traczyk
Department of Physiology, Institute of Physiology and Biochemistry, Medical University of Lodz, 90-131 Lodz, Poland
Objective. To investigate the influence of substance P on gonadotropin release
from the pituitary as evaluated according to the final effect, i.e. the ovulation.
Methods. Stainless steel tube was implanted into the 3rd cerebral ventricle and substance P (SP), C-terminal hexapeptide of Substance P (SP6-11), Gn-RH and adrenaline were infused on the 3th day of the cycle (proestrus). The oviducts were then isolated on the day of estrus and the ova were counted.
Results. SP or SP6-11 inhibited the ovulation which was not prevented by intracerebroventricular (i.c.v.) capsaicin pretreatment. The i.c.v. administration of anti-SP antibodies or Met-Enkephalin did not had any effect on the ovulation. The i.c.v. administration of noradrenaline on the 7-8th day of pseudopregnancy induced the ovulation which was prevented by the injection of SP immediately before noradrenaline.
Conclusions. It is suggested that noradrenergic neurons which control the ovulation by influencing the release of Gn-RH into pituitary portal vessels are affected by SP-ergic neurons.
Key words: Substance P - Capsaicin - Noradrenaline - Met-Enkephalin - Ovulation -
Pseudopregnancy - 3rd Cerebral Ventricle
Endocrine regulations, Vol. 33, 161 - 167, 1999
Download full text in PDF format (109 kB)
A. Yoenem, B. Cakyr, Oe. Azal, A. Corakcy, M. Kutlu, M. Oezata
Department of Endocrinology, Guelhane School of Medicine, 06018 Etlik, Ankara, Turkey
Objective. To present two cases with thyrotropin-secreting adenoma and the
effectiveness of octreotide acetate treatment on their tumor size as well as on thyroid
stimulating hormone (TSH) and thyroid hormone levels.
Case reports. The first case presented with tremor, palpitations and sweeting as suggestive of hyperthyroidism, but the other one presented with predominantly headache, while the other symptoms such as palpitation and nervousness were less prominent and he also did not have any thyroid enlargement at physical examination. Thyroid hormone levels in both cases were increased. However, TSH levels were not suppressed thus indicating an inappropriate secretion of TSH. Moreover, TSH levels did not change after T3 and TRH administration, which also contributed to the assumption of an inappropriate TSH secretion. One case had no increase in the TSH alpha subunit level, while this was increased in the other one. Both magnetic resonance imaging and somatostatin receptor scintigraphy revealed that there was a microadenoma (the first case; 6x7 mm in diameter) and a macroadenoma (the second case; 14X18 mm in diameter). Both patients were placed on a therapy with somatostatin analog octreotide (Sandostatin, Sandoz). Octreotide was initially given at a dose of 300 microg daily and then increased gradually up to 600 microg per day. There was some decrease in the levels of TSH and thyroid hormones at first. However, such decreases did not persist with ongoing therapy for 6 months. In addition, there was no change in the tumor size with this therapy at the end.
Conclusions. We conclude that the treatment by somatostatin analogue octreotide may not be an effective means of reducing the pituitary tumor size, though it may be used to reduce TSH and thyroid hormones temporarily.
Key words: TSH secreting adenoma - Octreotide treatment - Case reports - Minireview
Endocrine regulations, Vol. 33, 169 - 174, 1999
Download full text in PDF format (538 kB)
A. Russinova, B. Nikolov, Ch. Valkova
Institute of Experimental Morphology and Anthropology, Department of Cell
Institute of Molecular Biology, Department of Cell Biology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
Objective. To localize (by the light and electron microscopy) and partially
characterize the antigen recognized by the Mab 4E6 in rat ovaries.
Methods. Monoclonal antibody (4E6) against a rat ovarian granulosa cell antigen was prepared and identified the 40kDa protein specific for rat steroid producing cells. The localization of this antigen was studied by light and electron microscopic immunocytochemistry.
Results. The immunocytochemical observation suggested that the recognized antigen was localized in granulosa and thecal cells in all stages of follicular development. The intensity of immunostaining was found to depend on the developmental stage. In granulosa and thecal stage (health follicle) Mab 4E6 binding mollecule was localized on the membranes of rough endoplasmic reticulum (RER) and on the surface of lipid droplets in close association with the RER. In atretic follicles we established that the final destination of the visualized antigen is in structures which we refer as the autofagic vacuoles in close contact with the steroidogenic organelles. In addition, we observed Mab 4E6 binding molecule in the cytoplasm of luteal cells, Leydig cells and adrenocortical cells.
Conclusions. The results indicate that the 40kDa antigen may be common to all of rat steroidogenic organs. Our results suggest that the 40kDa protein may be associated with the processes governing steroidogenesis and/or follicular development.
Key words: Monoclonal antibody - 40 kDa antigen - Immunocytochemistry - Ovarian
follicle - Steroidogenesis
Endocrine regulations, Vol. 33, 175 - 182, 1999
Download full text in PDF format (1396 kB)
M. Bakalska, M. Mourdjeva, A. Russinova, S. Kyurkchiev, I. Kehayov
Institute of Experimental Morphology and Anthropology and
Institute of Biology and Immunology of Reproduction, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
Objective. Since the atrial natriuretic factor (ANF) is synthesized in various
peripheral tissues, where it acts in an autocrine or paracrine fashion, the aim was to
gain new insight into ANF expression and function in rat testis after Leydig cell
Methods. Leydig cell destruction was performed by the treatment with ethane dimethane sulphonate (EDS).
Results. ANF was expressed after Leydig cell destruction and total elimination (24 h and 7 days after EDS treatment) and also after Leydig cell regeneration (21 and 45 days after EDS treatment). ANF staining in the interstitial compartment was observed in apoptotic Leydig cells 24 h after treatment. In seminiferous epithelium ANF labeling was detected in Sertoli and germ cell cytoplasm with a more prominent labeling in spermatids. The degenerating germ cells were totally labeled.
Conclusions. The demonstration of ANF staining in seminiferous epithelium after Leydig cells elimination and androgen deprivation suggests that Leydig cells are not the sole source of ANF in rat testis and that the seminiferous epithelium may be a new site in which ANF may be synthesized. The result indicates that ANF plays a role in regulating gonadal function.
Key words: ANF - Testis - Immunocytochemistry - Ethane dimethane sulfonate - Rat
ENDOCRINE REGULATIONS, Vol. 33, 183-191, 1999
Download full text in PDF format (1459 kB)
ENDOCRINE REGULATIONS, Vol. 33, 192-194, 1999
Download full text in PDF format (42 kB)