The biological basis and clinical significance of hormonal imprinting, an epigenetic process

Enhancing gosling growth and secretion of somatotrophic and thyrotrophic axis hormones through egg turning during incubation

1. Growth performance of Yangzhou geese hatched from eggs with turning angles of 50° or 70° was evaluated in association with serum hormones and somatotrophic gene mRNA expression.2. Egg turning at 70° significantly (P< 0.05) increased hatchability, gosling quality and hatching weight. Gosling post-hatch body weight, leg and breast muscle weight in the 70° turning group was significantly heavier until 50 d of age.3. Serum concentrations of GH were significantly higher until 30 d of age in the 70° turning group goslings, and those of IGF-I and T3 were higher from hatching to 50 d of age.4. The mRNA expression of GHRH, pituitary GH, liver and leg muscle IGF-I were all significantly higher at 1 and 30 d of age after hatch, but not at 70 d after hatch, in the 70° turning group.5. Egg turning at 70° during incubation improves embryo and gosling quality and growth performance through up-regulation of gene expression and secretion of somatotrophic axis hormones, GHRH, GH and IGF-I, as well as T3.

Exposure to Atrazine through gestation and lactation period led to impaired sexual maturation and subfertility in F1 male rats with congenital deformities in F2 progeny

Several scientific reports suggest perturbed reproductive and developmental defects associated with environmental exposure to Atrazine (ATR). ATR has been associated with altered endocrine and reproductive functioning in-vivo exposed during the critical window of development. Thus, the present study investigates the effect of ATR exposure on F1-F2 male progeny exposed through gestation and lactation. F0 dams administered with ATR at doses 2, 10, 70, and 100 mg/kg b. wt/day from gestation day 6 to postnatal day 21. The F1 male rats were monitored for sexual maturation and subjected to fertility assessment on PND75. Delayed testicular descent was observed in 10, 70, and 100 mg/kg b. wt/day ATR dose with significantly lower serum testosterone, sperm count, and motility with testicular defects in F1 male. Expression of Androgen receptor (AR), Estrogen receptors (ER α and ER β), StAR, Aromatase, and INSL-3 were upregulated at all doses indicating estrogenic/anti-androgenic activity of ATR. Fertility assessment revealed subfertility in F1 males with high (%) pre- and post-implantation loss at 10, 70, and 100 mg/kg b. wt/day dose as compared to control. Further, F2 fetuses exhibited congenital disabilities viz. decreased weight, crown-rump length, and anogenital distance with several other morphological deformities. To conclude, ATR exerted estrogenic and/or anti-androgenic activity with fetotoxic effects through the male germline.

The effect of selected in ovo green light photostimulation periods on post-hatch broiler growth and somatotropic axis activity

Targeted in ovo green light (GL) photostimulation during the last days of broiler egg incubation increases embryonic expression of the somatotropic axis, similar to in ovo green light photostimulation from embryonic day (ED) 0 to the end of incubation. The aim of this study was to examine the effect of selected in ovo GL photostimulation periods on post-hatch broiler growth. Four hundred twenty fertile broiler eggs were divided into 7 treatment groups: the first incubated in the dark (standard conditions) as a negative control; the second incubated under monochromatic GL from ED0-ED20 (positive control); the third group incubated under monochromatic GL light from ED15-ED20; the fourth, fifth and sixth groups were incubated under monochromatic GL on ED16, ED17, and ED18, respectively; and the seventh group was incubated under monochromatic GL from ED18-ED20. All illumination was provided intermittently using LED lamps. After hatch, all chicks were transferred to a controlled room under standard rearing conditions. The group incubated under green light from ED18 until hatch showed similar results to the positive control group in body weights, as well as breast muscle weights (as % of body weights), and an elevation in the somatotropic axis activity during the experiment. We suggest that broiler embryos can be exposed to in ovo GL photostimulation from ED18 until hatch (hatching period), and still exhibit the same performance as obtained by photostimulation from d 0 of incubation.

Birth signalling hormones and the developmental consequences of caesarean delivery

Rates of delivery by caesarean section (CS) are increasing around the globe and, although several epidemiological associations have already been observed between CS and health outcomes in later life, more are sure to be discovered as this practice continues to gain popularity. The components of vaginal delivery that protect offspring from the negative consequences of CS delivery in later life are currently unknown, although much attention to date has focused on differences in microbial colonisation. Here, we present the case that differing hormonal experiences at birth may also contribute to the neurodevelopmental consequences of CS delivery. Levels of each of the 'birth signalling hormones' (oxytocin, arginine vasopressin, epinephrine, norepinephrine and the glucocorticoids) are lower following CS compared to vaginal delivery, and there is substantial evidence for each that manipulations in early life results in long-term neurodevelopmental consequences. We draw from the research traditions of neuroendocrinology and developmental psychobiology to suggest that the perinatal period is a sensitive period, during which hormones achieve organisational effects. Furthermore, there is much to be learned from research on developmental programming by early-life stress that may inform research on CS, as a result of shared neuroendocrine mechanisms at work. We compare and contrast the effects of early-life stress with those of CS delivery and propose new avenues of research based on the links between the two bodies of literature. The research conducted to date suggests that the differences in hormone signalling seen in CS neonates may produce long-term neurodevelopmental consequences.

No population left behind: Improving paediatric drug safety using informatics and systems biology

Adverse drugs effects (ADEs) in children are common and may result in disability and death. The current paediatric drug safety landscape, including clinical trials, is limited as it rarely includes children and relies on extrapolation from adults. Children are not small adults but go through an evolutionarily conserved and physiologically dynamic process of growth and maturation. Novel quantitative approaches, integrating observations from clinical trials and drug safety databases with dynamic mechanisms, can be used to systematically identify ADEs unique to childhood. In this perspective, we discuss three critical research directions using systems biology methodologies and novel informatics to improve paediatric drug safety, namely child versus adult drug safety profiles, age-dependent drug toxicities and genetic susceptibility of ADEs across childhood. We argue that a data-driven framework that leverages observational data, biomedical knowledge and systems biology modelling will reveal previously unknown mechanisms of pediatric adverse drug events and lead to improved paediatric drug safety.

Possible contribution of trained immunity in faulty hormonal imprinting and DOHaD: Review and hypothesis

The faulty hormonal imprinting theory (published in 1980) and the DOHaD (Developmental Origin of Health and Disease theory (published in 1986) are twin-concepts: both justify the manifestation after long time (in adults) diseases which had been provoked in differentiating cells (e.g. during gestation). This was demonstrated using animal experiments as well, as comparative statistical methods (in human cases). However, there is no explanation for the tools of memorization (even after decades) of the early adversity and the tools of execution (manifestation) in adult age. It seems likely that immune memory is involved to the memorization of early adversity, up to the manifestation of the result (non-communicable diseases). Nevertheless, the relatively short timespan of adaptive immune memory makes this system insuitable for this function, however the newly recognized trained memory of the innate immune system seems to be theoretically suitable for the storage of the records and handling the sequalae, which is the epigenetic reprogramming in the time of provocation, without changes in base sequences (mutation). The flawed (damaged) program is manifested later, in adult age. Evidences are incomplete, so further animal experiments and human observations are needed for justifying the theory.

Reprogramming of the Immune System by Stress and Faulty Hormonal Imprinting

PURPOSE

Hormonal imprinting is taking place perinatally at the first encounter between the developing hormone receptors and their target hormones. However, in this crucial period when the developmental window for physiological imprinting is open, other molecules, such as synthetic hormones and endocrine disruptors can bind to the receptors, leading to faulty imprinting with life-long consequences, especially to the immune system. This review presents the factors of stress and faulty hormonal imprinting that lead to reprogramming of the immune system.

METHODS

Relevant publications from Pubmed since 1990 were reviewed and synthesized.

FINDINGS

The developing immune system is rather sensitive to hormonal effects. Faulty hormonal imprinting is able to reprogram the original developmental program present in a given cell, with lifelong consequences, manifested in alteration of hormone binding by receptors, susceptibility to certain (non-infectious) diseases, and triggering of other diseases. As stress mobilizes the hypothalamic-pituitary-adrenal axis if it occurred during gestation or perinatally, it could lead to faulty hormonal imprinting in the immune system, manifested later as allergic and autoimmune diseases or weakness of normal immune defenses. Hormonal imprinting is an epigenetic process and is carried to the offspring without alteration of DNA base sequences. This means that any form of early-life stress alone or in association with hormonal imprinting could be associated with the developmental origin of health and disease (DOHaD). As puberty is also a period of reprogramming, stress or faulty imprinting can change the original (developmental) program, also with life-long consequences.

IMPLICATIONS

Considering the continuous differentiation of immune cells (from blast-cells) during the whole life, there is a possibility of late-imprinting or stress-activated reprogramming in the immune system at any periods of life, with later pathogenetic consequences.

Gestational and lactational exposure to triclosan causes impaired fertility of F1 male offspring and developmental defects in F2 generation

Triclosan (5-chloro-2-(2, 4-dichlorophenoxy) phenol, TCS), is a broad-spectrum antimicrobial agent and extensively used in household and daily daycare products. Recently, several reports have demonstrated the endocrine disruptive action of TCS to alter the testicular steroidogenesis. However, the gestational and lactational effects of TCS exposure on F1 offspring has not been studied. Present study aimed to investigate the effect of gestational and lactational exposure to TCS on F1 male progeny and its effect on fertility. Pregnant dams (F0) were administered with different doses of TCS (0.1, 4, 40 and 150 mg/kg b. wt./day) and Diethylstilbestrol (1 μg/kg b. wt./day), as a positive control daily by subcutaneous injection during Gestation Day 6 to Postnatal Day 21. Delayed testicular descent was observed at 150 mg/kg b. wt./day dose group. Dose-dependent decrease in testosterone level, sperm count and motility was observed. Significantly decreased expression of steroid hormone receptors (AR, ERα and ERβ), StAR and aromatase were observed in F1 male rats; indicating its prolonged effect on spermatogenesis and steroidogenesis in adulthood and poor development in F2 fetuses. Further, gestational and lactational exposure to TCS has negative impact on the fertility of F1 male rats. The F1 male rats were found sub-fertile with increased (%) pre- and post-implantation loss (at 40 and 150 mg/kg b.wt./day dose) with a simultaneous decrease in litter size. The significant decrease in mean fetal weight and crown-rump length (CRL) of F2 fetuses were observed at 0.1, 4, 40 and 150 dose groups indicating impaired development of F2 fetuses caused by TCS exposure. Present study emphasizes for the first time that TCS exposure during the vulnerable developmental time point (gestation and lactation) adversely affects reproductive functions and fertility of F1 male rats, which were transmitted to F2 generations leading to reduced CRLs and weights of F2 fetuses.

Aromatic hydrocarbon receptors in the immune system: Review and hypotheses

Ah-receptors (AhRs) recognize and bind foreign environmental molecules as well as some target hormones of other nuclear receptors. As ligands activate transcription factors, they transmit the information on the presence of these molecules by binding to the DNA, which in turn activate xenobiotic metabolism genes. Cross talk with other nuclear receptors or some non-nuclear receptors also activates or inhibits endocrine processes. Immune cells have AhRs by which they are activated for physiological (immunity) or non-physiological (allergy and autoimmunity) processes. They can be imprinted by hormonal or pseudo-hormonal (environmental) factors, which could provoke pathological alterations for life (by faulty perinatal hormonal imprinting). The variety and amount of human-made new environmental molecules (endocrine disruptors) are enormously growing, so the importance of AhR functions is also expanding.

Hormesis and immunity: A review

The hormesis concept demonstrates that in contrast to the toxic effect of high doses of materials, irradiation, etc., low doses of them are beneficial and, in addition, help to eliminate (prevent) the deleterious effect of high doses given after it. By this effect, it is an important factor of (human) evolution protecting man from harmful impacts, similarly to the role of immunity. However, immunity is also continuously influenced by hormetic effects of environmental [chemical (pollutions), physical (background irradiations and heat), etc.] and medical (drugs and therapeutic irradiations) and food interactions. In contrast to earlier beliefs, the no-threshold irradiation dogma is not valid in low-dose domains and here the hormesis concept is valid. Low-dose therapeutic irradiation, as well as background irradiations (by radon spas or moderately far from the epicenter of atomic bomb or nuclear facilities), is rather beneficial than destructive and the fear from them seems to be unreasonable from immunological point of view. Practically, all immune parameters are beneficially influenced by all forms of low-dose radiations.

Hormonal Imprinting: The First Cellular-level Evidence of Epigenetic Inheritance and its Present State

Hormonal imprinting takes place perinatally at the first encounter between the developing hormone receptor and its target hormone. This process is needed for the normal function of the receptor-hormone pair and its effect is life-long. However, in this critical period, when the developmental window is open, related molecules (members of the same hormone family, synthetic hormones and hormone-like molecules, endocrine disruptors) also can be bound by the receptor, causing life-long faulty imprinting. In this case, the receptors’ binding capacity changes and alterations are caused at adult age in the sexual and behavioral sphere, in the brain and bones, inclination to diseases and manifestation of diseases, etc. Hereby, faulty hormonal imprinting is the basis of metabolic and immunological imprinting as well as the developmental origin of health and disease (DOHaD). Although the perinatal period is the most critical for faulty imprinting, there are other critical periods as weaning and adolescence, when the original imprinting can be modified or new imprintings develop. Hormonal imprinting is an epigenetic process, without changing the base sequence of DNA, it is inherited in the cell line of the imprinted cells and also transgenerationally (up to 1000 generations in unicellulars and up to the 3_rd generation in mammals are justified). Considering the enormously growing number and amount of faulty imprinters (endocrine disruptors) and the hereditary character of faulty imprinting, this latter is threatening the whole human endocrine system.

Bone Manifestation of Faulty Perinatal Hormonal Imprinting: A Review

Hormonal imprinting takes place at the first encounter between the developing receptor and its target hormone and the encounter determines the receptor's binding capacity for life. In the critical period of development, when the window for imprinting is open, the receptor can be misdirected by related hormones, synthetic hormones, and industrial or communal endocrine disruptors which cause faulty hormonal imprinting with life-long consequences. Considering these facts, the hormonal imprinting is a functional teratogen provoking alterations in the perinatal (early postnatal) period. One single encounter with a low dose of the imprinter in the critical developmental period is enough for the formation of faulty imprinting, which is manifested later, in adult age. This has been justified in the immune system, in sexuality, in animal behavior and brain neurotransmitters etc. by animal experiments and human observations. This review points to the faulty hormonal imprinting in the case of bones (skeleton), by single or repeated treatments. The imprinting is an epigenetic alteration which is inherited to the progeny generations. From clinical aspect, the faulty imprinting can have a role in the pathological development of the bones as well, as in the risk of osteoporotic fractures, etc.

Intrinsic and Extrinsic Thymic Adrenergic Networks: Sex Steroid-Dependent Plasticity

The thymus is sexually differentiated organ providing microenvironment for T-cell precursor differentiation/maturation in the major histocompatibility complex-restricted self-tolerant T cells. With increasing age, the thymus undergoes involution leading to the decline in efficacy of thymopoiesis. Noradrenaline from thymic nerve fibers and "(nor)adrenergic" cells is involved in the regulation of thymopoiesis. In rodents, noradrenaline concentration in thymus and adrenoceptor (AR) expression on thymic cells depend on sex and age. These differences are suggested to be implicated in the development of sexual diergism and the age-related decline in thymopoiesis. The programming of both thymic sexual differentiation and its involution occurs during the critical early perinatal period and may be reprogrammed during peripubertal development. The thymic (re)programming is critically dependent on circulating levels of gonadal steroids. Although the underlying molecular mechanisms have not yet been elucidated fully, it is assumed that the gonadal steroid action during the critical perinatal/peripubertal developmental periods leads to long-lasting changes in the efficacy of thymopoiesis partly through (re)programming of "(nor)adrenergic" cell networks and AR expression on thymic cells.

Vitamin-caused faulty perinatal hormonal imprinting and its consequences in adult age

Lipid-soluble vitamins (vitamins A, D, E, and K) are actually hormones (exohormones), as they can be directly bound by hormone receptors or are in connection with molecules, which influence hormone receptors. Vitamin D is a transition between endo- and exohormones and the possibility of similar situation in case of other lipid-soluble hormones is discussed. The perinatal exposition with these “vitamins” can cause faulty perinatal hormonal imprinting with similar consequences as the faulty imprinting by the synthetic endohormones, members of the same hormone family or industrial, communal, or medical endocrine disruptors. The faulty imprinting leads to late (lifelong) consequences with altered hormone binding by receptors, altered sexuality, brain function, immunity, bone development, and fractures, etc. In addition, as hormonal imprinting is an epigenetic process, the effect of a single exposure by fat-soluble vitamins is inherited to the progeny generations. As vitamins are handled differently from hormones; however, perinatal treatments take place frequently and sometimes it is forced, the negative late effect of faulty perinatal vitamin-caused hormonal imprinting must be considered.

The Immunoendocrine Thymus as a Pacemaker of Lifespan

The thymus develops from an endocrine area of the foregut, and retains the ancient potencies of this region. However, later it is populated by bone marrow originated lymphatic elements and forms a combined organ, which is a central part of the immune system as well as an influential element of the endocrine orchestra. Thymus produces self-hormones (thymulin, thymosin, thymopentin, and thymus humoral factor), which are participating in the regulation of immune cell transformation and selection, and also synthesizes hormones similar to that of the other endocrine glands such as melatonin, neuropeptides, and insulin, which are transported by the immune cells to the sites of requests (packed transport). Thymic (epithelial and immune) cells also have receptors for hormones which regulate them. This combined organ, which is continuously changing from birth to senescence seems to be a pacemaker of life. This function is basically regulated by the selection of self-responsive thymocytes as their complete destruction helps the development (up to puberty) and their gradual release in case of weakened control (after puberty) causes the erosion of cells and intercellular material, named aging. This means that during aging, self-destructive and non-protective immune activities are manifested under the guidance of the involuting thymus, causing the continuous irritation of cells and organs. Possibly the pineal body is the main regulator of the pacemaker, the neonatal removal of which results in atrophy of thymus and wasting disease and its later corrosion causes the insufficiency of thymus. The co-involution of pineal and thymus could determine the aging and the time of death without external intervention; however, external factors can negatively influence both of them.

An epigenetic basis for autism spectrum disorder risk and oral contraceptive use

In the United States 1 in 68 children are diagnosed with autism spectrum disorder (ASD). Although the etiology is unknown, many scientists believe ASD is caused by a combination of genetic and environmental factors and/or epigenetic factors. The widespread use of oral contraceptives is one environmental risk factor that has been greatly overlooked in the biomedical literature. Oral contraceptives, synthetic hormones created to imitate natural human hormones and disrupt endogenous endocrine function to inhibit pregnancy, may be causing the harmful neurodevelopmental effects that result in the increased prevalence of ASD. It is conceivable that the synthetic hormones repeatedly assault the oocyte causing persistent changes in expression of the estrogen receptor beta gene. Ethinylestradiol, a known endocrine disruptor, may trigger DNA methylation of the estrogen receptor beta gene causing decreased mRNA resulting in impaired brain estrogen signaling in progeny. In addition, it is possible the deleterious effects are transgenerational as the estrogen receptor gene and many of its targets may be imprinted and the methylation marks protected from global demethylation and preserved through fertilization and beyond to progeny generations. This article will delineate the hypothesis that ethinylestradiol activates DNA methylation of the estrogen receptor beta gene causing decreased mRNA resulting in diminished brain estrogen signaling in offspring of mothers exposed to oral contraceptives. Considering the detrimental epigenetic and transgenerational effects proposed, it calls for further study.

Early-life Exposure to Endocrine Disrupting Chemicals and Later-life Health Outcomes: An Epigenetic Bridge?

A growing body of evidence demonstrates that adverse events early in development, and particularly during intrauterine life, may program risks for diseases in adult life. Increasing evidence has been accumulated indicating the important role of epigenetic regulation including DNA methylation, histone modifications and miRNAs in developmental programming. Among the environmental factors which play an important role in programming of chronic pathologies, the endocrine-disrupting chemicals (EDCs) that have estrogenic, anti-estrogenic, and anti-androgenic activity are of specific concern because the developing organism is extremely sensitive to perturbation by substances with hormone-like activity. Among EDCs, there are many substances that are constantly present in the modern human environment or are in widespread use, including dioxin and dioxin-like compounds, phthalates, agricultural pesticides, polychlorinated biphenyls, industrial solvents, pharmaceuticals, and heavy metals. Apart from their common endocrine active properties, several EDCs have been shown to disrupt developmental epigenomic programming. The purpose of this review is to provide a summary of recent research findings which indicate that exposure to EDCs during in-utero and/or neonatal development can cause long-term health outcomes via mechanisms of epigenetic memory.

Is oxytocin a maternal-foetal signalling molecule at birth? Implications for development

The neuropeptide oxytocin was first noted for its capacity to promote uterine contractions and facilitate delivery in mammals. The study of oxytocin has grown to include awareness that this peptide is a neuromodulator with broad effects throughout the body. Accumulating evidence suggests that oxytocin is a powerful signal to the foetus, helping to prepare the offspring for the extrauterine environment. Concurrently, the use of exogenous oxytocin or other drugs to manipulate labour has become common practice. The use of oxytocin to expedite labour and minimise blood loss improves both infant and maternal survival under some conditions. However, further investigations are needed to assess the developmental consequences of changes in oxytocin, such as those associated with pre-eclampsia or obstetric manipulations associated with birth. This review focuses on the role of endogenous and exogenous oxytocin as a neurochemical signal to the foetal nervous system. We also examine the possible developmental consequences, including those associated with autism spectrum disorder, that arise from exogenous oxytocin supplementation during labour.

Gene-environment interactions in human health: case studies and strategies for developing new paradigms and research methodologies

THE SYNERGISTIC EFFECTS OF GENES AND THE ENVIRONMENT ON HEALTH ARE EXPLORED IN THREE CASE STUDIES: adult lactase persistence, autism spectrum disorders, and the metabolic syndrome, providing examples of the interactive complexities underlying these phenotypes. Since the phenotypes are the initial targets of evolutionary processes, understanding the specific environmental contexts of the genetic, epigenetic, and environmental changes associated with these phenotypes is essential in predicting their health implications. Robust databases must be developed on the local scale to deconstruct both the population substructure and the unique components of the environment that stimulate geographically specific changes in gene expression patterns. To produce these databases and make valid predictions, new, locally focused, and information-dense models are needed that incorporate data on evolutionary ecology, environmental complexity, local geographic patterns of gene expression, and population substructure.

Immunoendocrinology: faulty hormonal imprinting in the immune system

Hormonal imprinting is an epigenetic process which is taking place perinatally at the first encounter between the developing hormone receptors and their target hormones. The hormonal imprinting influences the binding capacity of receptors, the hormone synthesis of the cells, and other hormonally regulated functions, as sexual behavior, aggressivity, empathy, etc. However, during the critical period, when the window for imprinting is open, molecules similar to the physiological imprinters as synthetic hormone analogs, other members of the hormone families, environmental pollutants, etc. can cause faulty imprinting with life-long consequences. The developing immune system, the cells of which also have receptors for hormones, is very sensitive to faulty imprinting, which causes alterations in the antibody and cytokine production, in the ratio of immune cells, in the defense against bacterial and viral infections as well as against malignant tumors. Immune cells (lymphocytes, monocytes, granulocytes and mast cells) are also producing hormones which are secreted into the blood circulation as well as are transported locally (packed transport). This process is also disturbed by faulty imprinting. As immune cells are differentiating during the whole life, faulty imprinting could develop any time, however, the most decisive is the perinatal imprinting. The faulty imprinting is inherited to the progenies in general and especially in the case of immune system. In our modern world the number and amount of artificial imprinters (e.g. endocrine disruptors and drugs) are enormously increasing. The effects of the faulty imprinters most dangerous to the immune system are shown in the paper. The present and future consequences of the flood of faulty imprintings are unpredictable however, it is discussed.

Effect of a single neonatal oxytocin treatment (hormonal imprinting) on the biogenic amine level of the adult rat brain: could oxytocin-induced labor cause pervasive developmental diseases?

Perinatal single-hormone treatment causes hormonal imprinting with lifelong consequences in receptor-binding capacity, hormone production as well as in social and sexual behavior. In the present experiments, newborn rats were treated with a single dose of oxytocin, and the levels of biogenic amines and their metabolites were studied in 8 different brain regions and in the sera when the male and female animals were 4 months old. Both dopaminergic and serotonergic neurotransmission was found to be significantly influenced. The levels of 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindole acetic acid metabolites decreased in the hypothalamus and striatum. Dopamine, serotonin, norepinephrine, and 5-hydroxytryptophol levels were hardly altered, and there was no difference in the epinephrine levels. The results show that dopamine and serotonin metabolism of hypothalamus and striatum are deeply and lifelong influenced by a single neonatal oxytocin treatment Oxytocin imprinting resulted in decreased dopamine turnover in the hypothalamus and decreased serotonin turnover in the hypothalamus, medulla oblongata, and striatum of females. As the disturbance of brain dopamine and serotonin system has an important role in the development of pervasive developmental diseases (eg, autism) and neuropsychiatric disorders (eg, schizophrenia), the growing number of oxytocin-induced labor as a causal factor, cannot be omitted.

Hormonal imprinting in the central nervous system: causes and consequences

The notion of the perinatal „hormonal imprinting” has been published at first in 1980 and since that time it spred expansively. The imprintig develops at the first encounter between the developing receptor and the target hormone – possibly by the alteration of the methylation pattern of DNA – and it is transmitted to the progeny generations of the cell. This is needed for the complete development of the receptor’s binding capacity. However, molecules similar to the target hormone (hormone-analogues, drugs, chemicals, environmental pollutants) can also bind to the developing receptor, causing faulty imprinting with life-long consequences. This can promote pathological conditions. Later it was cleared that in other critical periods such as puberty, imprinting also can be provoked, even in any age in differentiating cells. The central nervous system (brain) also can be mistakenly imprinted, which durably influences the dopaminergic, serotonergic and noradrenergic system and this can be manifested – in animal experiments – in alterations of the sexual and social behavior. In our modern age the faulty hormonal imprintig is inavoidable because of the mass of medicaments, chemicals, the presence of hormone-like materials (e.g. soya phytosteroids) in the food, and environmental pollutants. The author especially emphasizes the danger of oxytocin, as a perinatal imprinter, as it is used very broadly and can basically influence the emotional and social spheres and the appearance of certain diseases such as auitism, schizophrenia and parkinsonism. The danger of perinatal imprinters is growing, considering their effects on the human evolution. Orv. Hetil., 2013, 154, 128–135.

Investigation on chemotactic drug targeting (chemotaxis and adhesion) inducer effect of GnRH-III derivatives in Tetrahymena and human leukemia cell line

GnRH-III has been shown to exert a cytotoxic effect on the GnRH-R positive tumor cells. The chemotactic drug targeting (CDT) represents a new way for drug delivery approach based on selective chemoattractant guided targeting. The major goal of the present work was to develop and investigate various GnRH-III derivatives as potential targeting moieties for CDT. The cell physiological effects (chemotaxis, adhesion, and signaling) induced by three native GnRHs (hGnRH-I, cGnRH-II, and lGnRH-III) and nine GnRH-III derivatives were evaluated in two model cells (Tetrahymena pyriformis and Mono Mac 6 human monocytes). According to our results, the native GnRH-III elicited the highest chemoattractant and adhesion inducer activities of all synthesized peptides in micromolar concentrations in monocytes. With respect to chemoattraction, dimeric derivatives linked by a disulfide bridge ([GnRH-III(C)](2) ) proved to be efficient in both model cells; furthermore, acetylation of the linker region ([GnRH-III(Ac-C)](2) ) could slightly improve the chemotactic and adhesion effects in monocytes. The length of the peptide and the type of N-terminal amino acid could also determine the chemotactic and adhesion modulation potency of each fragment. The application of the chemoattractant GnRH-III derivatives was accompanied by a significant activation of phosphatidylinositol 3-kinase in both model cells. In summary, our work on low-level differentiated model cells of tumors has proved that GnRH-III and some of its synthetic derivatives are promising candidates to be applied in CDT: these compounds might act both as carrier, delivery unit, and antitumor agents.

Hormonal imprinting in the unicellular Tetrahymena: the proto-model of epigenetics

The unicellular ciliate, Tetrahymena has a complete hormonal system. It has receptors for receiving hormones, produces, stores and secretes hormones, similar to mammalian ones and has signal transduction pathways, for transmitting the information given by the hormones. The first encounter with a hormone provokes the hormonal imprinting under the effect of which the further encounters with the same hormone induces altered (usually enhanced) reaction (hormone binding, hormone synthesis, chemoattraction, movement, growth etc.). The effect of imprinting is durable, it can be observed also after 1000 generations, or after one year in non-dividing cells. Receptors of the nuclear envelope also can be imprinted. The plasma membrane receptors provoked by imprinting are similar to the receptors of mammals. Although steroid hormones are not present in Tetrahymena, the production of them and their receptors can be induced by imprinting. The hormonal imprinting is an epigenetic process and inhibition of DNA-methylation alters the imprinting. Hormonal imprinting in Tetrahymena was likely the first epigenetic phenomenon which was justified at cellular level. It is very useful for the unicells, as it helps to avoid dangerous molecules more easily or to find useful ones and by this contributes to the permanence of the population's life.

The hormonal system of the unicellular Tetrahymena: a review with evolutionary aspects

The unicellular ciliate, Tetrahymena has receptors for hormones of the higher ranked animals, these hormones (e.g. insulin, triiodothyronine, ACTH, histamine, etc.) are also produced by it and it has signal pathways and second messengers for signal transmission. These components are chemically and functionally very similar to that of mammalian ones. The exogenously given hormones regulate different functions, as movement, phagocytosis, chemotaxis, cell growth, secretion, excretion and the cells' own hormone production. The receptors are extremely sensitive, certain hormones are sensed (and response is provoked) at 10-21 M concentration, which makes likely that the function could work by the effect of hormones produced by the Tetrahymena itself. The signal reception is selective, it can differentiate between closely related hormones. The review is listing the hormones produced by the Tetrahymena, the receptors which can receive signals and the signal pathways and second messengers as well, as the known effects of mammalian hormones to the life functions of Tetrahymena. The possible and justified role of hormonal system in the Tetrahymena as a single cell and inside the Tetrahymena population, as a community is discussed. The unicellular hormonal system and mammalian endocrine system are compared and evolutionary conclusions are drawn.

Adolescent idiopathic scoliosis (AIS), environment, exposome and epigenetics: a molecular perspective of postnatal normal spinal growth and the etiopathogenesis of AIS with consideration of a network approach and possible implications for medical therapy

Genetic factors are believed to play an important role in the etiology of adolescent idiopathic scoliosis (AIS). Discordant findings for monozygotic (MZ) twins with AIS show that environmental factors including different intrauterine environments are important in etiology, but what these environmental factors may be is unknown. Recent evidence for common chronic non-communicable diseases suggests epigenetic differences may underlie MZ twin discordance, and be the link between environmental factors and phenotypic differences. DNA methylation is one important epigenetic mechanism operating at the interface between genome and environment to regulate phenotypic plasticity with a complex regulation across the genome during the first decade of life. The word exposome refers to the totality of environmental exposures from conception onwards, comprising factors in external and internal environments. The word exposome is used here also in relation to physiologic and etiopathogenetic factors that affect normal spinal growth and may induce the deformity of AIS. In normal postnatal spinal growth we propose a new term and concept, physiologic growth-plate exposome for the normal processes particularly of the internal environments that may have epigenetic effects on growth plates of vertebrae. In AIS, we propose a new term and concept pathophysiologic scoliogenic exposome for the abnormal processes in molecular pathways particularly of the internal environment currently expressed as etiopathogenetic hypotheses; these are suggested to have deforming effects on the growth plates of vertebrae at cell, tissue, structure and/or organ levels that are considered to be epigenetic. New research is required for chromatin modifications including DNA methylation in AIS subjects and vertebral growth plates excised at surgery. In addition, consideration is needed for a possible network approach to etiopathogenesis by constructing AIS diseasomes. These approaches may lead through screening, genetic, epigenetic, biochemical, metabolic phenotypes and pharmacogenomic research to identify susceptible individuals at risk and modulate abnormal molecular pathways of AIS. The potential of epigenetic-based medical therapy for AIS cannot be assessed at present, and must await new research derived from the evaluation of epigenetic concepts of spinal growth in health and deformity. The tenets outlined here for AIS are applicable to other musculoskeletal growth disorders including infantile and juvenile idiopathic scoliosis.