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L K Malendowicz

Publications and source records attributed to L K Malendowicz.

At least 217 records · Page 12Linked to original sources
PubMed1984

Sex differences in adrenocortical structure and function. XVII. Analysis of adrenal growth rate in maturing male and female rats and hamsters.

The aim of the study was to analyse the rate of adrenal growth of maturing rat and hamster of both sexes in relation to age, body weight and body surface. In the course of postnatal onto-genesis--days 21 to 77 in rats and 21 to 96 in hamsters--all of the estimated relations between body weight and body surface on adrenal size in both sexes of rat and hamster were almost linear. The values of all analysed regression line slopes are higher in female rats when compared to male animals. Male hamsters had higher values of regression line slopes than females. The results of the study suggest higher activity of the adrenal gland in female rat and male hamster when compared with the animals of opposite sex.

Adrenal Glands↗
PubMed1984

Sex differences in adrenocortical structure and function. XVI. Stereological and karyometric studies on the cortex of the suprarenal gland of intact adult male and female Mongolian gerbils (Meriones unguiculatus).

The histological structure of intact adult male and female Mongolian gerbil (Meriones unguiculatus) suprarenal cortex has been described, and quantitative stereological and karyometric studies were performed. The weight of the gland relative to body weight was higher in female than in male gerbils, but the volume of the gland was similar in both sexes. The relative volume of the zona reticularis was higher in the female, while no sex difference was observed in the absolute volume of all suprarenal components (expressed in mm3). In all cortical zones, average cell volume was higher in the female; the nuclear volume of the zona glomerulosa and zona reticularis were also higher in the female. In the zona fasciculata, some large cells with large nuclei (greater than 210 micrometers 3) were observed. These are probably polyploid cells and have not been described in other species. The suprarenal cortex of the male gerbil contained more parenchymal cells than that of the female, the difference being dependent upon variation in the number of cells in the zona fasciculata and zona reticularis. Despite these structural differences, gland homogenates from male and female animals secreted similar amounts of cortisol and the plasma levels in the two sexes were the same.

Adrenal Cortex↗
PubMed1984

Sex differences in adrenocortical structure and function. XV. Cellular composition and quantitative ultrastructural study of adrenal cortex of adult male and female hamster.

Cellular composition of adrenal cortex of adult male and female hamster was evaluated and parallel quantitative ultrastructural studies were performed. The adrenal cortex of adult male hamster contained more parenchymal cells than that of female and the difference depended mainly upon the number of the zona glomerulosa and zona fasciculata cells. Moreover, cells and nuclei of the zona reticularis were markedly larger in male animals. Ultrastructural observations of both male and female adrenal glands did not reveal any significant difference; however, stereology showed that the volumes of mitochondrial compartment and membrane space, as well as the surface areas of mitochondrial cristae and smooth endoplasmic reticulum tubules were significantly higher in the male hamster zona reticularis cells. Cortisol output by adrenal slices and homogenates per unit weight of the gland was higher in male than in female hamster. On the ground of these data, it seems conceivable that the observed sex-differences in the rate of cortisol output by hamster adrenal gland depend upon the higher number of the zona fasciculata cells and larger size of the zona reticularis cells in male than female gland.

Adrenal Cortex↗
PubMed1983

Sex differences in adrenocortical structure and function. XII. Stereologic studies of rat adrenal cortex in the course of maturation.

This paper reports a stereological study of the cellular aspects of development of the adrenal cortex of male and female rats in the course of maturation. Rats of the Wistar strain were studied at weekly intervals from day 21 to day 77 of postnatal life. From day 42 homogenates of adrenals from female rats produced more corticosterone than homogenates from males of corresponding age. In the strain of rats studied sex differences in adrenal weight appeared at about day 49. From this day onward relative, and subsequently absolute adrenal weights were higher in females than in males. In the course of maturation the total volume of all adrenocortical zones gradually increased. From day 70 the zona glomerulosa and from day 49 the zona fasciculata were larger in female than in male rats, while no distinct sex difference was observed in the volume of the zona reticularis. The appearance of sex-related differences in the adrenal cortex depends mainly on changes in the zona fasciculata, the cells of which markedly increased in volume in female rats by comparison with males. The total number of all adrenocortical cells increased from ca 13 million on day 21 to ca 25 million on day 77 and at all intervals studied adrenal glands of male and female rats contained a similar number of parenchymal cells.

Adrenal Cortex↗
PubMed1983

Effects of testosterone on the zona fasciculata of the male rat adrenal cortex. A correlated stereological and biochemical study.

The effects of long-term testosterone administration on the adrenal cortex of male rats were investigated by coupled morphometric and biochemical methods. Morphometry showed that testosterone treatment provoked a time-dependent atrophy of the zona fasciculata cells, which was mainly due to the decrease in the volume of the mitochondrial compartment and smooth endoplasmic reticulum (SER). Biochemical assays demonstrated that the decrease in the surface area per cell of SER membranes and mitochondrial cristae was tightly paralleled by the decrease in the activity per cell of two key enzymes of steroid synthesis contained in them (delta 5-3 beta-hydroxysteroid dehydrogenase and 11 beta-hydroxylase). The testosterone-induced inhibition of the growth maintenance and steroidogenic capacity of adrenocortical cells provoked a significant fall in the plasma concentration of corticosterone and a consequential increase in the level of circulating ACTH. Chronic administration of testosterone caused a notable suppression of the activity of the adrenal 5 alpha-reductase and this in turn provoked a rise in the intracellular concentration of corticosterone. Moreover, testosterone inhibited the incorporation of 3H-uridine into the nuclear and mitochondrial fractions of male rat adrenocortical cells. These findings exclude the possibility that the testosterone-provoked atrophy of the male rat adrenal glands is mediated by the suppression of the hypothalamo-hypophyseal axis, and suggest that the mechanism underlying this action of testosterone involves inhibition of nuclear and mitochondrial RNA synthesis. Whether this effect of testosterone is directly or indirectly mediated by the rise in the intracellular content of corticosterone due to the inhibition of 5 alpha-reductase activity, remains to be elucidated.

3-Hydroxysteroid Dehydrogenases↗
PubMed1982

Sex differences in adrenocortical structure and function. XI. Autoradiographic studies on cell proliferation and turnover in the adrenal cortex of the male and female rat and its dependence on testosterone and estradiol.

Adrenal glands from orchectomized and ovariectomized rats, with and without replacement therapy, and also from intact controls of both sexes, were examined by autoradiography with 3H-thymidine. The labelling index after 1 or 2 nucleoside injections was higher in the zona glomerulosa of females than in male rats, while no differences were found in the fascicular and reticular zones. Orchiectomy increased the labelling index in the fascicular and reticular zones, an effect prevented by testosterone. Ovariectomy did not change the labelling index, while estradiol lowered it in the zona glomerulosa. Duration of the S phase was longer in the zona fasciculata cells of males than in females. Both orchiectomy and testosterone shortened this phase in cells of the zona fasciculata and zona reticularis. Ovariectomy prolonged the S phase in the zona fasciculata and shortened this time in the reticular zone, an effect reversed by estradiol. In the glomerular and fascicular zones, cell cycle time was longer in males than in females. Orchiectomy shortened this time in all adrenocortical zones, an effect reversed by testosterone. Ovariectomy shortened cell cycle time in the glomerular and reticular zones and prolonged it in the zona fasciculata; these effects were reversed by estradiol. Turnover rate in adrenocortical cells was markedly higher in females than in males, a difference due to testosterone which markedly decreased turnover rate.

Adrenal Cortex↗
PubMed1982

Effects of long-term steroid suppression on rat adrenal 5 alpha-reductase and 11 beta-hydroxylase activities and corticosterone production in vitro.

The effects of prolonged steroid suppression on adrenal 5 alpha-reductase and 11 beta-hydroxylase activities and corticosterone production in vitro was studied in adult male rats. Cortisone acetate was administered at a dose of 2.5 mg/rat daily for 30 days and after that time at a dose of 5 mg/rat every other day. Autopsies were performed on 3, 6, 9, 12, 15, 20, 30, 60 and 120 days of experiment. Cortisone treatment resulted in a decrease in corticosterone output by quartered adrenals and an earlier and more marked drop in corticosterone production by whole adrenal homogenates. Steroid suppression leads to a marked increase in adrenal 5 alpha-reductase activity assayed on 12,000 X g supernatant, however on 120 day of experiment activity of the enzyme was markedly lower if compared with the earlier time-interval studied. 11 beta-hydroxylase activity, as tested in mitochondrial fraction, on day 12 of experiment was even higher than in control rats and thereafter a marked decline occurred. The studies suggest that adrenal steroid 5 alpha-reductase activity may participate in adaptation of adrenals to a disturbed hormonal status of the organism induced by cortisone treatment.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1982

Sex differences in adrenocortical structure and function. VIII. Karyometric and stereologic studies on adrenals of intact adult male and female hamsters.

Contrary to the rats, adrenals of the intact adult male hamsters are greater than females' ones. The aim of the study was to elucidate the cytologic aspects of these sex-associated differences in adrenal weight. Despite of equal body weight adrenals of male hamsters are markedly heavier then female glands and the same is true for the volume of the glands. Volume of al adrenocortical zones is larger in males than females animals, on the contrary, volume of medulla is greater in female hamster. The volume of zona glomerulosa cell is equal in both sexes while the cells of fasciculata and reticularis zones are greater in male animals. In the both sexes nuclear volume of glomerulosa and fasciculata cells was similar, on the contrary nuclei of zona reticularis cells are markedly larger in males. Total number of adrenocortical cells is higher in male glands as compared to female and this difference depends on the higher number of parenchymal cells in fasciculata and reticularis zones of the male gland. These data indicate that sex-associated difference in adrenal weight of the hamster depends on the differences in size as well as in quantity of adrenocortical cells in male and female glands.

Adrenal Cortex↗
PubMed1982

Sex differences in adrenocortical structure and function. IX. Stereologic studies on the effects of gonadectomy and testosterone or estradiol replacement on adrenal cortex of adult male and female hamsters.

Adrenal glands of adult male hamster are heavier than in female and this sex difference depends primarily on the greater number of adrenocortical cells and their larger size in male gland if compared to female. The aim of the study was to explain the relationship between the sex hormones and the structural of adrenal cortex of male and female hamsters. Orchidectomy lowered the adrenal weight, an effect partially reversed by testosterone. Changes induced by orchidectomy were found mainly in fasciculata and reticularis zones, after testosterone replacement the volume of the former did not differ from control males. Removal of testes lowered the volume of individual zona reticularis cell, after testosterone administration the volume of these cells did not differ from control males. Neither ovariectomy, nor estradiol replacement has a desired effect on the above mentioned parameters in female adrenal cortex. In both sexes gonadectomy lowered the total number of adrenocortical cells and this effect is not restored to normal by 12-days testosterone or estradiol action. Results obtained suggest that the sex dimorphism in the size and structure of hamster adrenal cortex depends on the stimulatory action of testosterone on the gland while estradiol has no distinct effect on parameters studied.

Adrenal Cortex↗
PubMed1982

Sex differences in adrenocortical structure and function. X. Lipid and corticosterone in the rat adrenal as affected by gonadectomy and testosterone or estradiol replacement.

Studies were performed on lipid and corticosterone content in adrenal glands of intact male and female rats and on their relation to gonadectomy and gonadal hormone replacement. Concentration of total lipid, total cholesterol, phospholipid and glycerides is similar in adrenals of adult male and female rats, however their content, due to larger adrenals, is markedly higher in females. Orchiectomy has no effect on concentration of lipid classes studied while their content in adrenals increased. Testosterone replacement resulted in an increase in concentration of total lipid and phospholipid and has no effect on total cholesterol and glyceride concentration. Ovariectomy evoked an increase in total lipid and phospholipid concentration, has no effect on glycerides and lowered total cholesterol concentration in rat adrenals, while estradiol replacement diminished concentration of all classes of lipids studied. Adrenal corticosterone concentration is higher in female than male rat while no differences in BT-positive steroid were observed. Orchiectomy increased corticosterone concentration, after testosterone administration the value did not differ from control. Ovariectomy has no effect and estradiol increases corticosterone concentration in the gland. Performed studies suggest that testosterone increases the concentration of main classes of lipids and decreases the corticosterone concentration in the rat adrenal cortex while estradiol has an opposite effect.

Adrenal Cortex↗
PubMed1981

Effect or partial hepatectomy on secretion and metabolism of corticosterone in the rat.

Investigations on the interrelationship between the rate of hepatic corticosterone metabolism intraadrenal 5 alpha-steroid reductase activity were performed in the rat. As an experimental model partially hepatectomized animals were employed. Male rats were studied 24 hrs, 3 and 8 days post surgery and female 5 and 8 days after partial hepatectomy. In male and female rats, partial hepatectomy caused an increase in adrenal 5 alpha-steroid reductase activity, however, this effect was observed only in rats studied 8 days post surgery, These results suggest the participation of the liver in the regulation of hypothalamo-pituitary-adrenocortical axis and show that intraadrenal 5 alpha-steroid reductase may be involved in this regulatory system.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1981

Sex dimorphism in the thyroid gland. III. Morphometric studies on the rat thyroid gland in the course of postnatal ontogenesis.

At weekly intervals between 21 and 84 days of postnatal ontogenesis, on the thyroid glands of male and female rats morphometric studies were performed. The rate of body growth was similar in male and female rats between 21 and 42 days. Thereafter male rats are heavier than females. There were no differences in composition of particular histologic components studied in the thyroids of male and female rats between 21 and 35 days. From day 42 the volume fraction of colloid is lower in the male than female gland. Also from day 49 of postnatal ontogenesis the follicular cells are taller in male than in female thyroid gland. After reaching puberty in the female thyroid gland a gradual lowering of the volume fraction of epithelium and an increase in volume fraction of colloid are observed. Due to these changes epithelium/colloid ratio in female rats markedly declines between 42 and 84 days of postnatal ontogenesis while in the male rats this ratio is higher and does not show such a distinct decline.

Animals↗
PubMed1980

In vitro studies of nuclear volume of rat adrenocortical cells: lace of ACTH effect.

The effect of ACTH on nuclear volume of adrenocortical cells in the zona fasciculata of rat adrenal cortex was examined in vitro. Sections of adrenal gland were incubated for 60 or 90 min in Krebs-Ringer's solution with 1% glucose in the presence of ACTH, actinomycin D, cycloheximide and aminoglutethimide. ACTH, despite its clear effect in stimulating steroidogenesis, did not exert a direct effect on the nuclear volume of cells studied. This phenomenon is not dependent upon the stimulation of steroidogenesis, since aminoglutethimide does not influence the nuclear volume of adrenocortical cells studied; rather, ACTH in the presence of aminoglutethimide leads to a decrease in their volume. Actinomycin D does not influence nuclear volume while after incubation with cycloheximide nuclei were larger than the control. The presence of ACTH did not alter this effect. These results indicate no relationship between the degree of corticosterone output and nuclear volume in rat adrenocortical cells of the zona fasciculata in vitro.

Adrenal Cortex↗