Effect of a single neonatal endorphin treatment on the hormone content of adult rat white blood cells and mast cells

Using flow cytometry and confocal microscopy, the presence of endorphin, serotonin and chorionic gonadotropin (hCG) was demonstrated in rat white blood cells and peritoneal mast cells. After a single neonatal treatment with beta-endorphin (hormonal imprinting), the mast cells of female rats reaching adulthood contained significantly less endorphin and serotonin, as well as slightly less hCG, than control cells. There was no change in the hormone content of the mast cells of males. The lymphocytes, monocytes and granulocytes of both sexes also contained the three hormones, but endorphin imprinting had no effect on these cells.     

Life-long effect of a single neonatal treatment with estradiol or progesterone on rat uterine estrogen receptor binding capacity.

Rats treated with a single dose of 17 beta-estradiol or progesterone within 24 h of birth were subjected to ovariectomy at 8 weeks of age and were nine days later examined for the binding capacity of the uterine estradiol receptors by saturation and competition tests (with diethylstilbestrol used as competitor). The Bmax value of the neonatally estradiol-treated rats (6.78 x 10(-10) M) was significantly decreased relative to the control (1.99 x 10(-9) M). The competition analysis affirmed these results. Neonatal progesterone treatment also accounted for a significant decrease (1.25 x 10(-9) M) in receptor concentration relative to the control (1.66 x 10(-9) M). Considering the competition analysis the decrease was less than in the case of estradiol and not even significant by saturation analysis. The uterine mass did not differ between the experimental and control rats, but part of those treated with estradiol developed ovarian cysts. It follows that not only synthetic steroids (DES, allylestrenol), but also an excessive presence of the physiological steroid hormone during the critical period of receptor maturation can account for a decrease in uterine receptor concentration in adulthood.     

Effect of tamoxifen treatment at adolescent age on the sexual behaviour and steroid hormone receptor binding of adult female rats

Hormonal imprinting takes place perinatally, at the first encounter between the target hormone and its developing receptor. However, there is a secondary critical period of imprinting at puberty. In these periods molecules similar to the hormones (members of the same hormone family, antagonists, certain environmental pollutants, etc.) can cause faulty imprinting with lifelong consequences. In the present experiments 5+2 days of tamoxifen treatment (120 microg/day) at adolescent age dramatically (from approx. 40% to 10%) reduced the sexual activity (Meyerson index and lordosis quotient) of female rats, soon after the finishment of the treatment and between four to six weeks after treatment. Similar results were observed in animals neonatally treated with allylestrenol and tamoxifen treated at puberty. Thymic glucocorticoid receptor and uterine estrogen receptor binding capacity were not influenced.     

Heterogeneity of steroid hormone receptor in adult rat lung cytosol

Chromatography on cellulose DEAE-52 columns revealed that the glucocorticoid receptor from rat lung cytosol consisted of a component in the 0.001 M prewash, revealed with synthetic steroids and natural mineralocorticoids, a second component eluted with 0.04 M PO₄, labelled with triamcinolone, dexamethasone, and a third moiety in the 0.06 M PO₄ region, evident with natural glucocorticoids (corticosterone, cortisol) as well as mineralocorticoids (aldosterone, deoxycorticosterone). The thrid component coelutedf with rat blood serum transcortin in double labelled experiments. Rat lung was devoid of another component in the 0.02 M PO₄ found in rat liver supernate and of the mineralocorticoid receptor evident only in rat kidney. Chromatography on Sephadex G-200 columns revealed a shift of radioactivity from a higher to a lower molecular weight region in the presence of 0.4 M KCl. Collectively, these studies indicate the subunit nature of the lung receptor as evidenced in most tissues hitherto tested. Moreover, polymorphism within a given subunit component can not be revealed by competition alone, as attempted by others, but can be revealed under selected conditions of physical separation.     

Influence of neonatal steroid (diethylstilbestrol, allylestrenol) treatment on the sexual behaviour of the adult rat

A single neonatal treatment with diethylstilbestrol (DES) or allylestrenol (AE) considerably depressed the sexual activity of male rats in adulthood. DES had a stronger depressive effect than AE. Though the adult sexual activity of intact female rats was also reduced by DES it was not influenced by AE. Ovariectomized females that had been hormone-treated before experimental mating showed reduced sexual activity under the influence of neonatal DES-treatment but increased sexual activity when treated neonatally with AE.     

Influence of prenatal steroid exposure on neonatal gonadotropin imprinting. Effect of single and combined hormone treatments on the chicken ovary

Chicken embryos treated with DES or AE at the 9th day of incubation showed postnatally an increase in ovarian mass, parenchymal zone thickness, follicle diameter and granulosa cell count. Perinatal gonadotropin treatment had a similar effect on these parameters in the control birds not receiving pretreatment, but had no influence on them in the birds pretreated with steroid. The tested ovarian parameters of the DES- and AE-pretreated birds still differed from the control at 6 weeks of age. Neonatal gonadotropin exposure induced imprinting in the birds not pretreated with steroid, to judge from an increased response (indicated by changed values of the tested parameters) to gonadotropin reexposure in adulthood. Similar, but considerably slighter changes were also shown by the steroid pretreated birds. It follows that in the birds prenatally exposed to AE or DES, supervening perinatal exposure to gonadotropin did not elicit greater changes than the prenatal exposure itself.     

Impact of a single neonatal gonadotropin (FSH + LH) or thyrotropin (TSH) treatment on the sexual behaviour of the adult male rat

A single gonadotropin (FSH + LH) treatment of neonatal male rats resulted in depression of sexual activity in adulthood. It appears that not only steroids, but also gonadotropins may alter adult sexual behaviour by a single neonatal exposure. The chemically related hormone thyrotropin (TSH) had a similar, but much less pronounced, effect on adult sexual activity.     

Influence of single neonatal treatment with allylestrenol or diethylstilbestrol on microsomal enzyme activity of rat liver in adulthood

A single neonatal treatment of rats with a steroid (allylestrenol or diethylstilbestrol) did not alter the later activity of the hepatic microsomal (cytochrome P-450) enzyme system, but inhibited the inducer action of another steroid (testosterone) administered at the age of six weeks. This suggests that a hormonal imprinting-like mechanism also operates in the case of enzymes.     

Effect of single neonatal treatment with the soy bean phytosteroid,genistein on the sexual behavior of adult rats

Hormonal imprinting develops during the perinatal critical period, when the target hormone meets the yet unmatured receptor. As a consequence of imprinting the receptor accomplishes its maturation reaching the binding capacity characteristic to adults. In this period in the presence of foreign molecules similar to the target hormone faulty imprinting may occur with life-long consequences. Soy bean contains phytosteroids which can mimic estrogen effects. In the present experiments single genistein (20 microg) or combined genistein + benzpyrene (20 microg) treatments were done neonatally and the sexual behavior of male and female adult animals was studied. Genistein significantly increased the lordosis quotient of females, which was compensated by neonatal benzpyrene treatment. Genistein also enhanced the sexual activity of males, and this was significantly not reduced by parallel benzpyrene treatment. The results show that neonatal genistein exposure can imprint sexual activity for life and the presence of a second imprinter can modify genistein's behavioral effect.     

Effect of neonatal treatment with mifepristone or tamoxifen on the binding capacity of the thymic glucocorticoid or uterine estrogen receptor of adult rats: data on the mechanism of hormonal imprinting

For studying the mechanism of perinatal hormonal imprinting newborn rats were treated with a single injection of the antihormones, mifepristone (RU486) or tamoxifen (100 microg each). Glucocorticoid receptors of thymi of 6 weeks old male and female, and uterine estrogen receptors of 2 months old female rats were studied for dexamethasone or estradiol binding, respectively. Tamoxifen caused faulty imprinting both in the thymic and uterine receptors, increasing affinity and density of males, and decreasing females' glucocorticoid receptors as well, as decreasing the density of uterine estradiol receptors. Neonatal mifepristone treatment was indifferent to the thymus, and decreasing to density of uterine estrogen receptors. Males' body weight significantly decreased 6 weeks after tamoxifen treatment. The results suggest that imprinting can not be provoked by a molecule (hormone antagonist) which can bind to the receptor without any postreceptorial events (mifepristone/glucocorticoid receptor), in the presence of some postreceptorial effects the reaction takes place, however the strongest reaction can be observed by the hormone analogue (tamoxifen) with postreceptorial (agonist) effect, not considering that the receptor is the direct target of the molecule or a cross-reaction is present.     

Influence of a single neonatal melatonin treatment on the basal and thyrotropin or melatonin modified blood thyroxine level of adult rats

Neonatal melatonin treatment caused a significant increase in thyroxine (T4) level at one month of age. Preexposure to melatonin in neonatal age and reexposure after one month accounted for a still greater increase in T4 production. Rats neonatally exposed to melatonin did not respond to TSH at one month of age.     

Effect of perinatal synthetic steroid hormone (allylestrenol, diethylstilbestrol) treatment (hormonal imprinting) on the bone mineralization of the adult male and female rat

Neonatal treatment with allylestrenol or diethylstilbestrol (DES) reduced the bone mineral content (BMC/bw) of the adult (four months old) female rats, without influencing bone mineral density (BMD/bw). In males these neonatal treatments elevated BMC and BMD alike. Ovariectomy alone decreased BMC and BMD alike; however the neonatal hormone treatments did not influence this reduced value. Ovariectomy of two months old animals increased body weight without the influence of neonatal hormone treatments. In adult males, the body weight was reduced significantly by neonatal DES and non-significantly by neonatal allylestrenol treatment. The experiments call attention to the possible human bone-effects of allylestrenol, which was used in the last decades as medication protecting endangered pregnancies.     

Effects of estrogen and growth hormone on steroid sulfatase activity and estrogen binding in rat liver

It is now well established that the activity of certain liver enzymes displays sex differences and that administration of human growth hormone to male rats alters the liver metabolism in a "female" direction. In this work we studied steroid sulfatase activity and binding of estradiol-17 beta in livers from intact rats and found a sex difference, with considerably higher enzyme activity in male as compared to female liver tissue. Continuous infusion of native and recombinant human growth hormone and estradiol-17 beta to male rats reduced sulfatase activity to "female" levels. A specific binding of estradiol-17 beta with receptor properties was found in the rat livers, but the concentration of binding sites did not change after administration of growth hormone or estradiol in this group of intact animals. Our data confirm previous reports that continuous administration of human growth hormone "feminize" liver metabolism, and since estradiol was found to have an identical effect on sulfatase activity it is suggested that the effect of estradiol-17 beta in this respect may be indirect, mediated via an altered secretory pattern of rat growth hormone.     

Impact of neonatal imprinting with vitamin A or D on the hormone content of rat immune cells

Neonatal single vitamin A (retinol; 3 mg) or vitamin D3 (cholecalciferol; 0.05 mg) treatment (imprinting) was done in male and female rats and 2 months later the endorphin, triiodothyronine (T3) and ACTH content of immune cells (peritoneal lymphocytes, monocyte-granulocyte-macrophage group [mo-gran], mast cells and thymic lymphocytes) were studied immunocytochemically by using flow cytometry and confocal microscopy. The T3 content was significantly decreased in peritoneal lymphocytes and in mo-gran and the endorphin content decreased in thymocytes of male animals, while ACTH was decreased in female lymphocytes and mo-gran. Vitamin D treatment was absolutely ineffective. The imprinting effects of vitamins A and D and their differences are discussed. The results call attention to the possible harmful effect of vitamin treatments during the perinatal critical period.     

Effect of chronic streptozotocin-induced diabetes on [3H]ouabain binding in the rat left ventricle

Earlier results from our laboratory have revealed that the inotropic response to ouabain was depressed in chronically diabetic rat heart (1). In this study we examined the effect of chronic streptozotocin induced diabetes (3 months) on [3H]ouabain binding in the rat heart. Scatchard analysis of [3H]ouabain binding to membrane preparations of rat left ventricle revealed two classes of binding sites; a high affinity/low capacity and a low affinity/high capacity binding site. The maximum number of binding sites of the high and low affinity binding sites in membrane preparations obtained from the chronically diabetic rats was significantly (p less than 0.05) reduced to 60.4 and 48.8% of controls, respectively. The dissociation constant of the high and the low affinity binding/sites in the chronically diabetic rat heart, compared to controls, was significantly (p less than 0.05) increased and decreased, respectively. These results suggest that the decreased inotropic response of ouabain in the intact tissue obtained from chronically diabetic rats (1) may be related to a decreased number of ouabain binding sites.     

Effect of neonatal streptozotocin and thyrotropin-releasing hormone treatments on insulin secretion in adult rats

Neonatal STZ (nSTZ) treatment results in damage of pancreatic B-cells and in parallel depletion of insulin and TRH in the rat pancreas. The injury of B-cells is followed by spontaneous regeneration but dysregulation of the insulin response to glucose persists for the rest of life. Similar disturbance in insulin secretion was observed in mice with targeted TRH gene disruption. The aim of present study was to determine the role of the absence of pancreatic TRH during the perinatal period in the nSTZ model of impaired insulin secretion. Neonatal rats were injected with STZ (90 microg/g BW i.p.) and the effect of exogenous TRH (10 ng/g BW/day s.c. during the first week of life) on in vitro functions of pancreatic islets was studied at the age 12-14 weeks. RT-PCR was used for determination of prepro-TRH mRNA in isolated islets. Plasma was assayed for glucose and insulin, and isolated islets were used for determination of insulin release in vitro. The expression of prepro-TRH mRNA was only partially reduced in the islets of adult nSTZ rats when compared to controls. nSTZ rats had normal levels of plasma glucose and insulin but the islets of nSTZ rats failed to response by increased insulin secretion to stimulation with 16.7 mmol/l glucose or 50 mmol/l KCl. Perinatal TRH treatment enhanced basal insulin secretion in vitro in nSTZ animals of both sexes and partially restored the insulin response to glucose stimulation in nSTZ females.