Single Neonatal Treatment Research Articles

Effect of neonatal benzpyrene imprinting on the brain serotonin content and nocistatin level in adult male rats

Single neonatal treatment (imprinting) with 20 microg benzpyrene results in significant increase of the brain serotonin level in the striatum, while in the other four regions (cortex, brainstem, hippocampus, hypothalamus) when measured in adults can be detected. The nocistatin level of cerebrospinal fluid (CSF) significantly decreases, while there is no change in the plasma nocistatin level. The results call attention to the comprehensive imprinting effect of benzpyrene, which in addition to receptorial, hormonal and sexual behavioral disturbances causes lasting differences in the brain serotonin and nocistatin levels, probably influencing mood and pain tolerance.

Effect of estradiol and progesterone on thyroid gland in pigs: A histochemical, stereological, and ultrastructural study

The cellular and subcellular organization of thyroid follicular cells in peripubertal (6-month-old) male pigs treated with estradiol-dipropionate (Oe) plus progesterone (Pr) in combination on the first postnatal day was studied. A stereological method was used for morphometric determinations of the relative volume densities of the follicular epithelium, colloid and interstitium, and for establishing the epithelial height and index of activation rate. Statistically significant differences of the examined parameters between the control and Oe+Pr -treated groups were determined by Student's t-test. The subcellular organization of thyroid follicular cells was studied using transmission electron microscopy (TEM). When compared with the control group, in the Oe+Pr -treated pigs, thyroid follicles possessed a noticeably higher follicular epithelium when compared with the control animals. The observed changes were quantified and comparison between the experimental groups showed that the height, volume density of follicular epithelium, and index of activation rate were significantly (P < 0.05) increased, whereas the relative volume density of the colloid was significantly (P < 0.05) decreased. At the subcellular level the thyroid follicular cells of Oe+Pr -treated pigs were characterized by increased number of polysomes and dense bodies and extensive endoplasmatic reticulum. It was concluded that a single neonatal treatment with female gonadal steroids exerted a prolonged effect on the pig's thyroid, characterized by increased biosynthesis and reabsorption of the colloid by the follicular cells.

Single neonatal treatment with β-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 μg β-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 adventage of females. The results call attention to the possibility of influencing pain-tolerance for life, by the pain-provoked endorphin levels during delivery.

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.

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.

Effect of a single treatment (imprinting) with genistein or combined treatment with genistein+benzpyrene on the binding capacity of glucocorticoid and estrogen receptors of adult rats.

Hormonal imprinting takes place perinatally at the first encounter between the hormone and its target receptor. This is needed for the normal finishment of the maturation of the receptor-signal transduction system. In excess of foreign molecules, which can also bind to the receptor, faulty imprinting develops with life-long consequences. Genistein, a soybean phytosteroid (isoflavone), has estrogen-like effects and can be bound by steroid receptors. In the present experiments, single neonatal treatment (imprinting) with 20 microg of genistein, or combined treatment with 20 microg of genistein+20 microg of benzpyrene was done and liver and thymus glucocorticoid receptors of adult male and female rats and uterine estrogen receptors were studied. There was no difference in the binding capacity of uterine estrogen receptors. Genistein treatment alone caused a significant reduction of liver glucocorticoid receptor density in males; however, there were no other significant alterations. After combined genistein+benzpyrene treatment, more.than half of the thymus and liver glucocorticoid receptor values significantly changed. The results call attention to the imprinting-modifying effect of a second (environmental) imprinter.

Gene therapy attenuates the elevated blood pressure and glucose intolerance in an insulin-resistant model of hypertension.

Fructose feeding in male Sprague-Dawley (SD) rats results in a mild hypertension and glucose intolerance. Although the mechanism of this glucose intolerance and hypertension is not completely understood, a role for the renin-angiotensin system (RAS) has been proposed. In the current study our aim was to test the hypothesis that intervention of the RAS with a gene therapy approach would be effective in preventing the development of hypertension and glucose intolerance in this animal model. Five-day-old SD rats were administered either an empty retroviral vector (LNSV) or retroviral vector containing AT1 receptor antisense DNA (AT1R-AS). The virus (25 microl, 8 x 10(9) CFU/ml) was injected into the heart and the animals were returned to their mothers. After weaning, half the animals from each group were placed on breeder's chow or a 60% fructose diet. Indirect blood pressures (BP) were determined and an oral glucose tolerance test (OGTT) was performed when the animals had been on the respective diets for 2 months. Fructose-fed animals developed mild hypertension (145 +/- 3 versus 132 +/- 4 mmHg) by 6 weeks of dietary intervention. This increase in BP was prevented by AT1R-AS treatment (125 +/- 3 mmHg). At 2 months of age, fasting blood glucose was comparable among the four groups; however, the glucose excursion during the OGTT was significantly greater and more prolonged in the LNSV-treated, fructose-fed group than the other three groups. AT1R-AS treatment significantly prevented glucose intolerance in the fructose rat to levels observed in the controls. Early fructose dietary treatment results in moderate hypertension and glucose intolerance, which is prevented by a single neonatal treatment with AT1R-AS. These results suggest that the RAS is involved in the glucose intolerance associated with fructose feeding and that genetic intervention is effective in this rat model.

The effect of a single neonatal treatment (hormonal imprinting) with the antihormones, tamoxifen and mifepristone on the sexual behavior of adult rats

Hormonal imprinting takes place perinatally during the first encounter between the hormone and its developing receptor. The presence of an excess of related molecules in that time provokes faulty (pathological) imprinting. In the present experiments single-neonatal treatment with 100 μ g of tamoxifen completely abolished the adult male and female rats’ sexual activity. Similar treatment with 100 μ g of mifepristone (RU486) significantly enhanced the males sexual activity and non-significantly increased that of the females. The results demonstrate the importance of pathological imprinting during the perinatal development of sexual behavior. There are clear differences between the molecules having steroid (mifepristone) or non-steroid (tamoxifen) character, mediated through a ligand–receptor complex, and its effect in activating particular genes.

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.

Effect of Vitamin D3 Treatment in the Neonatal or Adolescent Age (Hormonal Imprinting) on the Thymic Glucocorticoid Receptor of the Adult Male Rat

Single neonatal treatment with 25 μg vitamin D₃ 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 D₃ treatment (50 μg) 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 D₃ and its harmful effect on the development of other members of the steroid receptor superfamily, seems to be unquestionable.

Effect of perinatal vitamin A or retinoic acid treatment (hormonal imprinting) on the sexual behavior of adult rats.

Single neonatal treatment with vitamin A (retinol) dramatically reduced the sexual activity of adult male rats. In females there was a significant decrease in the Meyerson index and a non significant decrease in the lordosis quotient. The effect of three perinatal treatments (at the first, third and fifth day) with all-trans retinoic acid was much weaker, causing only a significant increase in the time of the first ejaculation in males and non-significant decrease in the lordosis quotient of females. The experiments call attention to the false imprinting provoking effect of materials acting on members of the steroid receptor superfamily with possible human health aspect.

Evidence for growth heterogeneity among foci with different phenotypes in the population of altered hepatocyte foci induced by a single neonatal treatment with carcinogen.

Relationships between phenotypic and growth characteristics of carcinogen-induced altered hepatocyte foci were investigated. Male and female rats were given a single i.p. injection of carcinogen (diethylnitrosamine or benzo[a]pyrene) within 1 day after birth and were exposed to dietary promoter (phenobarbital) beginning at weaning. Groups of these rats were then killed at intervals, and their livers were examined for foci exhibiting various phenotypic markers through the use of serial frozen sectioning techniques, histochemical staining and computer-assisted image analysis. These procedures permitted the identification and sizing of foci with different specific phenotypes (identities of focus markers) within each phenotypic complexity level (number of markers per focus). The data suggest that foci growth rates differ with respect to specific focus phenotypes within complexity levels. This observation complements previous demonstrations of a direct relationship between foci growth rates and levels of phenotypic complexity and indicates that the observed diversity of focus phenotypes reflects true biological diversity within the focus population. Given the prior evidence for (i) the stability of focus phenotypes; (ii) the rapid emergence of phenotypically dissimilar foci following a single carcinogen treatment; and (iii) the production of foci by single initiation events, we suggest that each proliferatively and phenotypically distinct member of the focus population reflects the occurrence of a lesion at a unique genetic locus during initiation.

Impact of neonatal treatment with cardioactive glycosides (digoxin, ouabain) on receptor binding capacity, blood level and cardiac function in the adult rat. Extension of the imprinting theory

1. 1. A single neonatal treatment with a cardioactive glycoside (ouabain, digoxin) altered the response of the adult rat to digitaloid treatment. 2. 2. As demonstrated by RIA, re-exposure to digoxin at 2 months of age was followed within 30 min by a more than twofold increase in serum digoxin over the not pretreated control and, although a steady concentration decrease followed, the experimental rats still had a higher serum digoxin level than the controls at 4 h. 3. 3. In the not presensitized control group the serum digoxin peak appeared at 60 min at a considerably lower level than the 30-min maximum of the experimental rats. 4. 4. Neonatal pretreatment with ouabain depressed myocardial ouabain binding, but enhanced the Na + K +-ATPase activity. 5. 5. The above differences were conspicuous in the functional response, yet a greater atrial response to the positive inotropic action of K-stophantoside and a greater ventricular response to beta adrenergic excitation were readily seen in the experimental group. 6. 6. It follows that not only hormones, but also other ligands acting at receptor level can be regarded as potential inducers of imprinting.