Permanence of the cell-to-cell transmission of insulin induced hormonal imprinting

When insulin-treated (imprinted) Chang liver cell cultures were mixed with cultures which did not receive insulin treatment the information of imprinting was transmitted to the cultures which were not in direct contact with insulin. The ability of the cells to transmit imprinting was long lasting and could be detected even after four weeks, when it was nearly of the same degree as at the first measurement. Difference was found between the binding capacity of the receptors of the plasma membrane and those of the nuclear membrane.     

Is the saccharide component of the insulin receptor involved in hormonal imprinting?

Hormonal imprinting takes place at the first interaction of a given hormone with the cell (the Tetrahymena in the present case) and accounts for a greater responsiveness to the hormone on re-exposure(s). The Tetrahymena is able to bind insulin and Concanavalin-A (Con-A) as well. Exposure to both ligands—simultaneously or in sequence—enhances the binding of both in the progeny generations. It follows that the lectin, which inhibits insulin binding by direct action, enhances rather than depresses the effect of insulin-induced imprinting.     

Influence of neonatal treatment with porcine insulin (hormonal imprinting) on the receptor binding of insulins of porcine, rat and human origin

A single neonatal insulin treatment in the male rat decreases, whereas in the female rat it increases, the number of insulin receptors detected at the age of one month. No difference could be observed in affinity. The extent of the binding of rat, porcine and human insulin is different (the binding of human insulin is the most pronounced), meanwhile the alterations evoked by neonatal treatment are basically identical.     

Single neonatal treatment with beta-endorphin (hormonal imprinting) extremely enhances nocistatin level of cerebrospinal fluid in adult rats

In earlier experiments endorphin treatment of newborn rats caused the decrease of brain serotonin content, increasing aggressivity, enhanced sexual activity of females and changes in the binding capacity of uterine estrogen receptors at adult age, however nociceptin content of the cerebrospinal fluid was not changed. In the present experiment neonatal treatment of male and female rats was done with a single dose of 3 microg beta-endorphin and in five months old rats the level of nociceptin antagonist nocistatin was determined by radioimmunoassay in the cerebrospinal fluid. In both genders the amount of nocistatin was one magnitude higher in the endorphin treated groups. There was also a significant difference between the male and female nocistatin level in the treated and non-treated groups alike, with the advantage of females. The results call attention to the possibility of influencing pain-tolerance for life, by the pain-provoked endorphin levels during delivery.     

Impact of single neonatal serotonin treatment (hormonal imprinting) on the brain serotonin content and sexual behavior of adult rats

Hormonal imprinting takes place perinatally at the first encounter between the developing receptor and its target hormone. As a consequence of imprinting the receptor accomplishes its maturation and reaches the binding capacity characteristic to the adult age. In the excess of target hormone or presence of molecules similar to the target hormone, which are able to bind to the unmatured receptors, faulty imprinting develops with life-long consequences. At present, serotonin was given to neonatal rats and their sexual activity, brain serotonin level and steroid receptor's binding capacity was measured in adult age. Brain serotonin level was significantly reduced in male's striatum and parallel with this, male's sexual activity significantly increased. In other regions of the male brain (prefrontal cortex, hypothalamus, hippocampus) there was a statistically non-significant tendency for a decrease in serotonin level. No significant differences were detected in female brain values, and there was only slight change in female's sexual activity. There was also no change in the binding capacity of thymic glucocorticoid and uterine estrogen receptors. The experiments call attention to the possibility of perinatal imprinting by a neurotransmitter causing changes in brain neurotransmitter level for life, which is manifested in altered sexual activity.     

Specificity of the cell-to-cell transmission of hormonal imprinting in cell cultures

Chang liver cells and Chinese hamster ovary (CHO) cells were imprinted either with insulin or with thyrotropin (TSH). Chang liver cells responded to insulin but not to TSH. As an effect of imprinting evoked by insulin administration the binding of insulin administered for the second time was enhanced. In the mixed culture of imprinted and intact cells the extent of the binding was similar to that seen in the cultures of the cells having received imprintatory treatment alone. CHO cells also responded to TSH, imprinting developed and was transmitted to the cells which were not in interaction with the hormone (intact cells). In CHO cells also insulin gave rise to imprinting for insulin, whereas TSH gave rise to moderate binding imprinting for insulin. On the other hand, insulin imprinting did not enhance the binding of TSH. The obtained results indicate that both the imprinting itself and the specificity of the transmission of imprinting depend on the characteristics of the cell-type in question. The extent of the transmission, however, is always proportional to the extent of imprinting.     

Effect of vitamin D(3) treatment in the neonatal or adolescent age (hormonal imprinting) on the thymic glucocorticoid receptor of the adult male rat

Single neonatal treatment with 25 microg vitamin D(3) significantly decreased the thymic glucocorticoid receptor density (B(max)) of 6-week-old male rats. In females, a similar treatment did not cause any changes. Single vitamin D(3) treatment (50 microg) during adolescence (i.e. 6-week-old animals) significantly increased the glucocorticoid receptor density in adult (10-week-old) males. No significant changes in receptor affinity (K(d)) could be observed. Considering that in earlier experiments similar neonatal treatments influenced bone mineral mass and sexual behavior, the hormonal imprinting effect of vitamin D(3) and its harmful effect on the development of other members of the steroid receptor superfamily, seems to be unquestionable.     

Taxon-dependence of receptor level cell-to-cell communication in Tetrahymena: possible explanation for the transmission of hormonal imprinting

Insulin treatment induced in Tetrahymena pyriformis a positive hormonal imprinting, and in Tetrahymena thermophila a negative imprinting, resulting in increased and decreased binding capacity, respectively, at re-exposure to the hormone. The imprinting, or the information associated with it, is transferred by the nutrient medium of the insulin-treated cells to those not treated. The issue of transfer depends on the nature of the receiver taxon, leading always to a positive imprinting in Tetrahymena pyriformis, and to a negative imprinting in Tetrahymena thermophila, regardless of the nature of the 'imprinted' transmitter taxon. The findings substantiate the transferability of hormonal imprinting by the nutrient medium at the unicellular level, the key role of the postreceptorial mechanism in determining the trend of imprinting and may explain the persistence of imprinting in the progeny generations.     

Influence of a single treatment with vitamin E or K (hormonal imprinting) of neonatal rats on the sexual behavior of adults

The effect of a single neonatal treatment (imprinting) with vitamin E or vitamin K1 on the sexual activity of three-month old rats, was studied. In female animals vitamin E treatment significantly lowered the Meyerson index and lordosis quotient, among males there were significantly more inactive animals and no multiple ejaculations could be observed. Vitamin K1 treatment caused only slight changes in the same direction, in both sexes. Considering also earlier results concerning vitamin A and D neonatal treatments (alterations in receptor binding capacity, sex hormone levels and sexual behavior), and receptorial changes caused by neonatal vitamin E and K1 treatments, the present experiment also calls attention to the lifelong effects of perinatal treatment with lipid soluble vitamins.     

Cell-mediated transmission of hormonal imprinting to virgin mammalian cells in culture and failure of transmission with the nutrient medium

Chinese hamster ovary (CHO) cells and Chang liver cells which had already interacted with a hormone (gonadotropin, TSH, insulin) in culture, transmitted hormonal imprinting to virgin cells not previously involved in the interaction. The information associated with imprinting was not mediated by the nutrient medium, because the nutrient medium of the hormone-treated cells did not induce imprinting in virgin cells and even reduced rather than enhanced the hormone binding capacity thereof. Thus the transmission of information is in all probability associated with a direct cell-cell contact.     

Single treatment (hormonal imprinting) of newborn rats with serotonin increases the serotonin content of cells in adults

Hormonal imprinting takes place perinatally at the first encounter between the hormone and its target receptor, causing the finishment of the maturation of receptor-signal transduction system. In the presence of an excess of the target hormone or related molecules faulty imprinting develops with life-long consequences. In earlier experiments single neonatal treatment with minute dose of IL-6 caused also prolonged stimulation of IL-6 production. In the present experiment newborn female and male rats were treated with 20 microg serotonin (hormonal imprinting) and were studied for serotonin content of different cell types in adult age. Serotonin content was measured by flow cytometry and its localization was determined by confocal microscopy. Serotonin content was detected in white blood cells (lymphocytes, monocytes and granulocytes); in lymphocytes, monocytes (macrophages), granulocytes and mast cells of peritoneal fluid and thymic lymphocytes. Serotonin was present in all cell types of control animals studied. Serotonin content extremely elevated in the white blood cells and also increased in the peritoneal cells of neonatally treated female animals. There was no elevation in thymic lymphocytes. The mean values of male animals remained at the control level. The experiments call attention to the life-long effect of the perinatal hormonal imprinting manifested presently in the elevation of serotonin content and point to the gender differences of serotonin imprinting. Considering the role of serotonin in mood and psychiatric diseases, the observations could have some clinical importance.     

Influence of neonatal insulin imprinting on the insulin binding capacity of rat erythrocytes in adulthood

A single neonatal insulin treatment decreased considerably the insulin binding capacity of erythrocytes in adult rats, by analogy of the behaviour of the hepatic insulin receptors in response to insulin exposure during the perinatal period, or during liver regeneration in adulthood. These observations substantitate earlier conclusions on the mechanism of imprinting and strongly suggest the universality of perinatal imprinting in living organisms. In vitro insulin exposure of the erythrocytes of adult rats depressed 48 h later the erythrocytic insulin binding capacity to a similar degree in individuals treated and not treated with insulin when newborn, from which it follows that neonatal exposure had no influence on erythrocytic response to later in vitro treatment. In the light of the present study the use of erythrocytes as model cells for imprinting studies deserves consideration.     

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% increase 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.     

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

Summary 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.     

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.     

Impact of combined hormonal pretreatment (insulin+TSH) on the imprinting of hormones administered in combination to Chinese hamster ovary cell culture.

Cultured Chinese hamster ovary (CHO) cells were treated (imprinted) with insulin and with thyrotropin (TSH) related to gonadotropins (FSH+LH). When one week later the treatment was repeated with one of the hormones, considerable differences could be observed in the binding capacity of the cells. In the hormone combination TSH was able to evoke persistent imprinting only to a markedly lesser degree than insulin, meanwhile the imprintatory effect of insulin was of greater extent even on the cell regarded to be unspecific for insulin. Hormone treatment of one hour duration--when investigated immediately after--did not extinct the binding capacity to TSH but enhanced that to insulin. With the deterioration of the conditions of culturing, the enhanced binding capacity disappeared.     

Insulin treatment (hormonal imprinting) increases the insulin production of the unicellular Tetrahymena long term. Is there a simultaneous formation of hormone receptor and hormone?

Insulin treatment of Tetrahymena pyriformis resulted in a long-lasting increase in the insulin content of the cells. After about 200 generations, insulin levels significantly higher than in the control were demonstrated by using a quantitative immunocytochemical method. Although the insulin content fluctuated from day to day, it was always higher in the insulin pre-treated (imprinted) cells than in the controls. The results emphasise the simultaneous stimulation of hormone and receptor formation by hormonal imprinting.     

Post-natal diet determines insulin resistance in fetally malnourished, low birthweight rats (F1) but diet does not modify the insulin resistance of their offspring (F2)

We examined the effects of prenatal and postnatal nutrition on birthweight and insulin sensitivity, indicated by the glucose/insulin (G/I) ratio, in adult rats (F1 generation) and in their adult offspring (F2 generation). Rat pups (F1) whose dams consumed low-protein diets during gestation (malnourished) consumed either nutritionally adequate (control) or high-fat diets ad libitum post-weaning. The offspring of these rats (F2) were maintained on the same diets as their respective dams. Separate pups (F1) whose dams consumed high-fat diets during gestation (over-nourished) were maintained on high-fat diets post-weaning, as were their offspring (F2). Birthweights were significantly reduced in all fetally malnourished F1 animals. At approximately 70 d of age, fasting insulin sensitivity in over-nourished F1 rats was significantly reduced compared to controls regardless of whether they were malnourished or over-nourished in utero; however, fetally malnourished F1 rats consuming control diets post-natally had significantly greater fasting insulin sensitivity than control animals. At 30 and 120 min post-glucose load, insulin sensitivity was reduced 12-65% in both groups of over-nourished F1 rats as compared to the fetally malnourished F1 rats consuming the control diet. Birthweights were significantly lower in F2 animals whose dams (F1) were fetally malnourished and weaned to high fat diets. Insulin sensitivity was significantly reduced in all F2 animals versus control animals, regardless of dietary treatment. Thus, post-natal diets alter insulin sensitivity in fetally malnourished, adult rats; and maternal malnutrition during gestation results in insulin resistance in offspring, irrespective of offsprings' birthweight or diet.