Hormonal Imprinting Research Articles

Effect of neonatal allylestrenol treatment (hormonal imprinting) on the serum testosterone and progesterone concentration in adult rat.

Serum testosterone concentration was significantly elevated in adult male rats by a single perinatal allylestrenol administration. One week after a second allylestrenol treatment in adulthood the hormone concentration dropped below the control values. Serum progesterone concentration was significantly lowered in adult female rats by a single perinatal allylestrenol administration. Following a second allylestrenol treatment in adulthood the hormone concentration reached the control values. These experiments demonstrate that the hormonal imprinting caused by allylestrenol (a steroid used in the treatment of endangered pregnancy) not only acts at receptor level and produces changes in sexual behaviour, but also induces modifications in serum hormone concentrations.

Insulin pretreatment (imprinting) produces elevated capacity in the insulin binding of Tetrahymena. Different binding by the cilia of the body and oral field

Gold-labeled insulin is bound first of all to the cilia of the oral field of Tetrahymena. A primary treatment (hormonal imprinting) with insulin increases the binding capacity even after 24h and makes it more sensitive for appearance a week later, within a minute of giving insulin-gold. The food vacuoles contain insulin-gold in pretreated cells or without pretreatment as well, though in imprinted situations the label can be found in pinocytotic vesicles at the bases of cilia in the oral field. Altogether, a functional difference can be observed between the cilia of the oral and non-oral surfaces of Tetrahymena and hormonal imprinting has a specifying effect on the binding of labeled hormone.

Infant feeding, fetal growth and adult thyroid function

Prolonged breast-feeding in humans is associated with increased low-density lipoprotein cholesterol and higher death rates from ischaemic heart disease in adult life. The reasons for this link are unclear. A possible explanation is that thyroid hormones present in breast milk and absorbed by the suckling infant could, by the process of hormonal imprinting, permanently down-regulate the set point of thyroid homeostasis. Thyroid hormones influence cholesterol metabolism, and could explain the link between infant feeding and the regulation of cholesterol levels in the adult. We therefore investigated whether infant feeding was related to adult thyroid function in 303 women aged 60-71 years who were born in the county of Hertfordshire, UK, where birthweight, the weight at 1 year and the method of infant feeding had been recorded routinely. Free thyroxine (FT4) concentrations but not free triiodothyronine (FT3) or thyrotrophin (TSH) were increased in the women who, as infants, had been breast-fed beyond 1 year of age (p < 0.01). In women who were bottle-fed, with or without breast-feeding, serum TSH rose and FT4 fell with increasing birthweight (p = 0.01 and p = 0.04, respectively). Although the metabolic significance of these findings is unclear, they suggest that the set point of thyroid function in the adult is determined by fetal growth and infant feeding.

The effect of neonatal sex hormone manipulation on the incidence of diabetes in nonobese diabetic mice.

The nonobese diabetic (NOD) mouse is a model of Type I (insulin-dependent) diabetes. It develops autoimmune pancreatic beta-cell lesions characterized by lymphocytic infiltration and beta-cell destruction. The incidences of diabetes for male and female NOD mice in our colony were 24% and 73%, respectively. In this study, we investigated the effect of neonatal manipulation of the sex hormone profile on the incidence of diabetes in male and female NOD mice. One day after birth, male mice were castrated and female mice were either ovariectomized, given testosterone, or ovariectomized and given testosterone. The mice were maintained for 140 days and blood samples were collected biweekly starting at 42 days old. Diabetes was determined by three consecutive blood glucose levels > 200 mg/dl. Neonatal gonadectomy increased the incidence of diabetes in males but decreased it in females. Females treated with testosterone also had a decreased incidence of diabetes, whereas ovariectomy plus testosterone increased the incidence to 100%. Castration decreased the body weight in males and increased body weight in females. Testosterone treatment with or without ovariectomy also increased body weight. From these studies, we concluded that neonatal hormonal imprinting has a significant influence on the incidence of diabetes in the NOD mouse.

Effect of inhibitors and activators of tyrosine kinase on insulin imprinting in Tetrahymena.

Primary exposure of Tetrahymena cells to insulin gave rise to hormonal (insulin) imprinting in the offspring generations, as judged from the increase in binding upon reexposure to insulin. Vanadate mimicked the action of insulin, inasmuch as it also induced imprinting for insulin, whereas the other tyrosine kinase activator tested, namely H2O2, had no such effect. However, combined treatment with vanadate+H2O2 + insulin induced a more pronounced imprinting for insulin than either insulin or vanadate on their own. The tyrosine kinase inhibitor genistein, a plant flavonoid, did not change the value for insulin binding significantly relative to the control immediately after exposure, but increased it slightly in the offspring generations after 24 h at high dilution. Upon combination with insulin, 10(-4)M genistein inhibited imprinting by insulin. These experimental observations suggest that there may be a key role for tyrosine kinase activity in the mechanism (development) of imprinting.

Correlation of insulin pretreatment and insulin binding of Amoeba proteus—a new technique for evaluation

1. 1. Insulin binding sites of Amoeba proteus were analysed. The developed technique helped to compare equivalent pseudopodia membranes, according to their fluorescein-isothiocyanate (FITC)-insulin binding capacity. 2. 2. The number of insulin binding sites decrease in the control conditions as a fraction of time. 3. 3. The down regulation of binding sites (or similar phenomenon) lasts ~48 hr. 4. 4. Only low concentrations of insulin can induce a binding site elevation in the long term. 5. 5. Hormonal imprinting could be presented in Amoeba. 6. 6. The developed technique is suitable for detection of membrane dynamics in Amoeba proteus.

Changes in the hormone dependency of epithelial cell proliferation in the genital tract of mice following neonatal oestrogen treatment

The genital tract epithelium of the female laboratory mouse has been widely studied as a model of oestrogen-dependent growth and proliferation. Perturbation of the hormonal imprinting of these tissues during neonatal development has also been used to study the development of pathological abnormalities, particularly in the cervical epithelium. This study demonstrates that mice treated neonatally from days 1–5 with supraphysiological concentrations of oestrogen are able to maintain high levels of proliferation following the removal of the ovaries later in adult life. This high level of proliferation was shown to be independent of the ovarian oestrogens and of oestrogens produced peripherally by aromatisation. These results suggest conversion of the genital tract in these mice to a fully hormonal “independent” state. However, neonatal treatment with oestrogen was not found to produce a uniform change to hormonal independence. Further challenge of the adult ovariectomised mice with oestrogen, demonstrated that a population of cells still retained the ability to respond to the mitogenic influence of this hormone.

Alteration of lipid composition in two taxa of Tetrahymena by first and repeated insulin treatment

1. 1. While the first insulin treatment of Tetrahymena pyriformis or T. thermophila does not cause any change in inorganic phosphor (P i) level, repeated treatment after hormonal imprinting enormously increases it. 2. 2. Con-A bound to sugar-side chains of the insulin receptors does not influence P i level. 3. 3. There are significant differences in the neutral lipid and phospholipid levels fater insulin and Con-A treatment, similarly or disparately in two taxa studied. 4. 4. The results support the hypothesis on the receptor forming effect of hormonal imprinting in Tetrahymena. 5. 5.The changes in lipid ratios does not explain the binding and functional differences in insulin effects of the two Tetrahymena taxa, observed previously.

Involvement of the phosphoinositol (PI) system in the mechanism of hormonal imprinting

Certain components of the phosphoinositol (PI) system are present in the unicellular Tetrahymena. Treatment of Tetrahymena with insulin did not alter the relative proportions of the examined six phospholipid components (PIP2, PIP, phosphatidylcholine, phosphatidylethanolamine, PI, PA), but the primary interaction (imprinting) with insulin accounted for an about 75% decrease in the PIP2 — level and an about 20% incrase in the phosphatidylethanolamine level. The experimental results strongly suggest that hormonal imprinting accounted for adjustment of the second messenger systems of Tetrahymena to an energy saving level.

Studies into hormonal imprinting in intact and transformed 3T3 fibroblast cell lines.

The cells of the NIH 3T3 fibroblast line responded to primary interaction with insulin by a positive imprinting, i.e. by an increased binding capacity for the hormone on re-exposure. Positive imprinting, although to a lesser degree, was also induced by thyrotropin. However, oncogenic transformation by polyoma virus oncogens resulted in decreased imprinting in both the middle-T-antigen (MT3) and small-T-antigen-expressing (N4) cells.

Induction of hormone receptor formation in the unicellular tetrahymena

Studies based on treatment with antibodies to thyrotropic hormone, luteotropic hormone, growth hormone or adrenocorticotropic hormone have shown that although the unicellular Tetrahymena does not possess sui generis receptors to all polypeptide hormones, such binding structures may arise, or become established in the membrane of the unicellular Tetrahymena in the presence of exogenous hormone. The Tetrahymena subjected to hormonal imprinting still contained an increased amount of hormone after six generation changes, which suggested that either hormone production had been induced by treatment, or the internalized hormone had not been degraded intracellularly. Thus the role of hormonal imprinting in receptor formation has also been substantiated by the immunocytochemical approach used in the present study.

Binding and functional studies of hormonal imprinting in different taxa of Tetrahymena

1. 1. Strains of five different taxa of Tetrahymena ( T. hegewischi, T. pigmentosa, T. pyriformis, T. thermophila, T. malaccensis) and the mutant strain T. thermophila MSI equally bound the vertebrate hormone insulin, and changed their response to it after primary interaction (imprinting). 2. 2. Imprinting-induced changes in the level of free intracellular Ca 2+ and PAS-positive material different from changes in the binding value immediately after primary interaction, but followed a similar trend to it 1 day later (on second exposure). 3. 3. The positive or negative trend of imprinting showed a correlation with the closeness of the phylogenetic relationship of the taxa covered in the study.

Effect of compounds acting on gap junctions and membrane fluidity on the course and cell-to-cell transmission of hormonal imprinting in cell culture

Effect of compounds acting on gap junctions and membrane fluidity on the course and cell-to-cell transmission of hormonal imprinting in cell culture

Changes in the patching and capping of insulin receptors under the influence of hormonal imprinting.

Binding of fluorescein-isothiocyanate-(FITC)-labeled insulin was followed up in the function of time in Chang liver cells pretreated and not pretreated with insulin. The not pretreated cells showed patching, but no capping of the receptors during the period of study (60 min), whereas the insulin-pretreated cells showed indications of capping already after 10 min. Patching of the insulin receptors was particularly conspicuous at the sites of cell-cell contact (at the intercellular junctions). Supra-nuclear patching occurred earlier in the control cultures, and on it followed the fluorescence of the nuclear chromatin.

Hormonal imprinting of the microsomal enzyme system in adults. Microsomal activity change in response to estrogen (DES, AE) treatment during liver regeneration.

Estrogen (diethylstilbestrol-DES or allylestrenol-AE) treatment applied to rats of both sexes during liver regeneration following subtotal hepatectomy had a long lasting influence on the inducibility by phenobarbital of the hepatic microsomal enzyme system of the females. The enzyme activities of the DES-treated females differed hardly from the baseline two weeks after treatment, but increased almost two-fold over control on induction with phenobarbital 5 and 7 weeks later. The AE-treated females showed a smaller although yet significant, enzyme activity increase only at 7 weeks. The influence of estrogens was negligible, and inhibitory rather than stimulatory, in the males. It appears that, in appropriate conditions, enzyme imprinting can also be induced in adult organisms, since, in all probability, availability for imprinting depends not so much on the age of the organism, as on the developmental state of the target cell.

Transmission of Hormonal Imprinting in Tetrahymena Cultures by Intercellular Communication

The primary interaction of cultured Tetrahymena cells with a hormone (insulin in the present case) gives rise to hormonal imprinting, which accounts for a considerable increase in the later hormone binding capacity of the cells. Mixed culturing of imprinted and not imprinted (virgin) cells results in transmission to the latter of the information mediated by imprinting and thereby in a considerable increase in hormone binding capacity over that of pure hormone-preexposed cell cultures. The material substrate of intercellular information transmission is a cellular secretion which appears in the nutrient medium, and is increasingly released in presence of not imprinted (virgin) cells in the mixed culture.

The mechanism of receptor development as implied by hormonal imprinting studies on unicellular organisms.

In higher organisms, the development of hormone receptors is genetically encoded and forms an integral part of cell membrane differentiation6. Full maturation of the receptor nevertheless requires the presence of the hormone for amplification (hormonal imprinting)4,7. Hormonal imprinting takes place at the primary interaction between target cell and hormone, and amplifies the cellular interacting structure (receptor) for specific binding of the hormone. It has been shown experimentally that hormonal imprinting can also occur in unicellular organisms4,6 if the hormone is present in their environment3. Thus the phenomenon of hormonal imprinting can be reproduced experimentally in unicellular model systems7.

Receptor ontogeny and hormonal imprinting.

Continuous interaction with the environment is a basic feature of cell life. Precise recognition of the environment is a prerequisite for cell function and survival. The environment of the unicellular organism is the external world. Transition from unicellular to multicellular forms of life involves dramatic alterations in the recognition system since, while the environment of the multicellular organism is still the external world, that of the single cell may be, depending on its localization, either the external or the internal milieu15,16. The at least partial ‘internalization’ of the environment at the level of multicellularity results in specialization of the recognition system (for the needs of the community). While the developing nervous system acquires the ability to receive scores of different signals and to control the entire (multicellular) organism, the primordial chemical system of signal recognition acquires different functions which become integrated into the complexity of the functions of the organism.KeywordsHormone ReceptorFollicle Stimulate HormoneInsulin BindingSpecific HormonePolypeptide HormoneThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Cytochemical investigation into the Ca-dependence of positive and negative hormonal imprinting in Tetrahymena.

Insulin gives rise to positive imprinting in Tetrahymena pyriformis, but to negative imprinting in T. thermophila, as revealed by the respective increases and decreases in the insulin-binding capacity of these organisms observed during later interactions with this hormone. We found that changes in insulin-binding capacity exhibited parallelism with fluctuations of the levels of free, intracellular Ca2+ detectable by Quin-2 labeling. An exception was the second interaction of T. thermophila with insulin, which although showing a positive trend, produced a relatively small increase in the level of intracellular Ca2+. These observations suggest an interrelationship between hormone-binding capacity and the fluctuation of intracellular Ca2+ levels. Either hormone binding depends on the availability of Ca2+, or, alternatively, the latter depends on the binding capacity. Further studies are required to elucidate the true nature of this interdependence.

The mechanism of receptor development as implied by hormonal imprinting studies on unicellular organisms.

In higher organisms, the development of hormone receptors is genetically encoded and forms an integral part of cell membrane differentiation6. Full maturation of the receptor nevertheless requires the presence of the hormone for amplification (hormonal imprinting)4,7. Hormonal imprinting takes place at the primary interaction between target cell and hormone, and amplifies the cellular interacting structure (receptor) for specific binding of the hormone. It has been shown experimentally that hormonal imprinting can also occur in unicellular organisms4,6 if the hormone is present in their environment3. Thus the phenomenon of hormonal imprinting can be reproduced experimentally in unicellular model systems7.