Sex-Dependent Changes in Striatal Dopamine Transport in Preadolescent Rats Exposed Prenatally and/or Postnatally to Methamphetamine

Methamphetamine (MA) is the most commonly used psychostimulant drug, the chronic abuse of which leads to neurodegenerative changes in the brain. The global use of MA is increasing, including in pregnant women. Since MA can cross both placental and haematoencephalic barriers and is also present in maternal milk, children of chronically abused mothers are exposed prenatally as well as postnatally. Women seem to be more vulnerable to some aspects of MA abuse than men. MA is thought to exert its effects among others via direct interactions with dopamine transporters (DATs) in the brain tissue. Sexual dimorphism of the DAT system could be a base of sex-dependent actions of MA observed in behavioural and neurochemical studies. Possible sex differences in the DATs of preadolescent offspring exposed to MA prenatally and/or postnatally have not yet been evaluated. We examined the striatal synaptosomal DATs (the activity and density of surface expressed DATs and total DAT expression) in preadolescent male and female Wistar rats (31–35-day old animals) exposed prenatally and/or postnatally to MA (daily 5 mg/kg, s.c. to mothers during pregnancy and lactation). To distinguish between specific and nonspecific effects of MA on DATs, we also evaluated the in vitro effects of lipophilic MA on the fluidity of striatal membranes isolated from preadolescent and young adult rats of both sexes. We observed similar changes in the DATs of preadolescent rats exposed prenatally or postnatally (MA-mediated drop in the reserve pool but no alterations in surface-expressed DATs). However, prenatal exposure evoked significant changes in males and postnatal exposure in females. A significant decrease in the activity of surface-expressed DATs was found only in postnatally exposed females sensitized to MA via prenatal exposure. MA applied in vitro increased the fluidity of striatal membranes of preadolescent female but not male rats. In summary, DATs of preadolescent males are more sensitive to prenatal MA exposure via changes in the reserve pool and those of preadolescent females to postnatal MA exposure via the same mechanism. The combination of prenatal and postnatal MA exposure increases the risk of dopaminergic deficits via alterations in the activity of surface-expressed DATs especially in preadolescent females. MA-mediated changes in DATs of preadolescent females could be still enhanced via nonspecific disordering actions of MA on striatal membranes.     

Prenatal testosterone exposure leads to hypertension that is gonadal hormone-dependent in adult rat male and female offspring

Prenatal testosterone exposure impacts postnatal reproductive and endocrine function, leading to alterations in sex steroid levels. Because gonadal steroids are key regulators of cardiovascular function, it is possible that alteration in sex steroid hormones may contribute to development of hypertension in prenatally testosterone-exposed adults. The objectives of this study were to evaluate whether prenatal testosterone exposure leads to development of hypertension in adult males and females and to assess the influence of gonadal hormones on arterial pressure in these animals. Offspring of pregnant rats treated with testosterone propionate or its vehicle (controls) were examined. Subsets of male and female offspring were gonadectomized at 7 wk of age, and some offspring from age 7 to 24 wk received hormone replacement, while others did not. Testosterone exposure during prenatal life significantly increased arterial pressure in both male and female adult offspring; however, the effect was greater in males. Prenatal androgen-exposed males and females had more circulating testosterone during adult life, with no change in estradiol levels. Gonadectomy prevented hyperandrogenism and also reversed hypertension in these rats. Testosterone replacement in orchiectomized males restored hypertension, while estradiol replacement in ovariectomized females was without effect. Steroidal changes were associated with defective expression of gonadal steroidogenic genes, with Star, Sf1, and Hsd17b1 upregulation in testes. In ovaries, Star and Cyp11a1 genes were upregulated, while Cyp19 was downregulated. This study showed that prenatal testosterone exposure led to development of gonad-dependent hypertension during adult life. Defective steroidogenesis may contribute in part to the observed steroidal changes.     

Neurotoxicological Examination of the Piglet Brain after Prenatal and Postnatal Exposure to Trichlorfon

Piglets were given 10 repeated doses of the orga-nophosphorus compound trichlorfon during the postnatal period in order to examine the effect on the brain development (Experiment 1). Following prenatal exposure to trichlorfon, the ability of a presumptive hypoplastic cerebellum and cerebrum at birth, to regenerate postnatally was investigated (Experiment 2). Administration of repeated doses of trichlorfon postnatally was accompanied by only small changes in brain weights, morphology and transmitter enzyme activity (choline acetyltransferase, glutamate decarboxylase, aromatic amino acid decarboxylase) in 35 days old piglets. Animals exposed prenatally, and sacrificed at the age of 35 days, showed a significant increase in brain weights and enzyme activities. The animals did, however, not reach control values in cerebral weight, cerebellar weight or total enzyme activities. Morphological changes still showed regional loss of Purkinje cells in the cerebellum. The study clearly indicated that the pig brain was less vulnerable to trichlorfon in the postnatal period of development than when exposed to the compound prenatally.     

Some Long-Lasting Neurochemical Efafects of Prenatal or Early Postnatal Exposure to Diazepam

Changes in the uptake of various neurotransmitters were measured in the frontal cortex and hippocampus of male and female rats that were exposed to diazepam through the placenta or through the mother's milk during the prenatal or early postnatal period of rapid brain development. Earlier studies from our laboratory showed that early diazepam exposure has long-lasting behavioral consequences. The present results show that prenatally diazepam-exposed rat pups show significant reduction in choline uptake in the frontal cortex at 10 days of age. At 60 days of age, both pre- and postnatally exposed males, but not females, show significant differences from controls in terms of choline uptake, whereas postnatally exposed females whose behavior was shown previously to be profoundly affected by the diazepam exposure showed significant increase in gamma-aminobutyric acid (GABA) uptake in the hippocampus and reduction of 5-hydroxytryptamine (5HT) uptake in the cortex at 60 days of age.     

Biological and psychosocial determinants of male and female human sexual orientation

Some propositions on male and female sexual orientation will be considered. Some of these are established; others are more speculative. The aim is to offer some notes towards a coherent, comprehensive theory of sexual orientation. 1. The distinction between butch and femme lesbians seems real rather than a social construct. 2. High levels of prenatal steroid hormones seem to be causally associated with the sexual orientation of butch lesbians. However it is not established whether the causal process operates prenatally or postnatally (or both). This is so because prenatal hormone levels are thought to correlate positively with postnatal hormone levels. And high postnatal hormone levels may facilitate homosexual behaviour as a consequence of sensation-seeking. 3. Male bisexuals also are interpreted to have been exposed to high prenatal testosterone levels. But (for reasons similar to those outlined above in regard to butch lesbians) it is unclear whether these have a direct prenatal effect on the brain or whether they are precursors of high postnatal testosterone levels, which are associated with male bisexual orientation by promoting sensation-seeking behaviour. 4. Postnatal learning processes seem to be causally involved in the sexual orientation of some femme lesbians and some exclusive male homosexuals. 5. Some homosexual men have genes that predispose to their sexual orientation. 6. The same may apply to some lesbians, but such genes have not, as far as I know, been identified. 7. People (of both sexes) who engage in same-sex sexual behaviour may be classified simultaneously in two ways, viz (1) 'active' vs 'passive' and (2) those who do and those who do not engage (or consider engaging) in sex with members of the opposite sex. Ex hypothesi, some of the 'active' ones initiate some of the 'passive' ones. The active ones are driven more by hormones and the passive ones by psychosocial factors. The active males contain a substantial proportion of self-identified bisexuals; and the active females a substantial proportion of self-identified butches. 8. These two active categories (butch lesbians and male bisexuals) share a number of endocrinological, psychological, morphological and behavioural features vis-a-vis their exclusively homosexual and heterosexual peers. Methods of testing some of these ideas are presented.     

The effects of different steroids on costal and epiphyseal cartilage of fetal and adult rats

Summary The effects of different doses of various steroids on growth, and on costal and epiphyseal chondrocytes, have been studied in prenatal, immature, and adult Long-Evans rats using histochemical techniques, and both light and electron microscopy. Both prenatal and postnatal treatments have been employed. The steroids used were cortisone (CA), betamethasome (BM), and, in the prenatal group only, dexamethasone (DM).Body weight is reduced in all treated rats (except the low dose of CA) by day 17 of gestation, with greater weight reductions occurring in rats receiving the higher dose level of each steroid. In rats treated prenatally or neonatally, and sacrificed postnatally on days 39–43 or days 116–127, body weights, and tibial and tail lengths, are less than in correspondingly aged controls, thus showing a persistence of the effects of treatment.Costal and epiphyseal cartilages in prenatal rats show cellular, synthetic, and ultrastructural alterations induced by treatment with glucocorticoids but the responses are not necessarily comparable. Except for the low dose of DM, the higher doses of each steroid are more effective in inhibiting, or altering, growth and cellular differentiation in the developing fetuses. Surprisingly, a low dose of DM has a more devastating effect on the cells and extracellular matrix of both costal and epiphyseal cartilage, than do higher dose-levels of the various steroids. Low doses of CA and BM are also effective in inhibiting or altering growth and cellular differentiation, but their effectiveness is largely limited to 17 days of gestation. The order of effect of the various doses of the different steroids on fetal cartilage, listed in decreasing order of severity, is as follows: 0.12 DM, 0.24 DM, 0.42 BM, 50 CA, with 25 CA and 0.18 BM being approximately equal and only slightly different from control cartilages. The effect of prenatal or neonatal glucocorticoid treatment on chondrocytes is minimal in the 30–43 day, or 116–127 day, postnatal groups. In immature and adult rats, cortisone affects the chondrocytes more deleteriously than does betamethasone, and a 5.0 mg dose of CA seems to affect chondrocytes, body weight, and tibial and tail lengths more than 0.2 or 7.5 mg doses.Supported in part by NIH grant HD 07074 and HD 12034     

Studies concerning the effects of low level prenatal X-irradiation on postnatal growth and adult behaviour in the Wistar rat

Fifty-nine pregnant Wistar strain rats were sham irradiated or subjected to a 0.1 or 0.2 Gy exposure of X-radiation on the 9th or 17th day of gestation. Twenty-seven of the females were killed at term for teratologic analysis. The remaining mothers raised their young. At 60 days of age the 252 offsprings were randomly assigned three of six tests: open field, swimming, hanging, activity wheel, water T-maze, or conditioned avoidance response. Male offspring exposed at the 0.2 Gy level exhibited retarded growth only during the first few weeks of postnatal life. Female offspring exposed on the 17th day to 0.2 Gy X-radiation were growth retarded throughout the test period. Postnatal growth rates, however, were not significantly different between the irradiated and control groups. There were no significant alterations in adult behaviour due to prenatal X-irradiation. There were sex differences in activity wheel and forelimb hanging performance, unrelated to radiation exposure. These results indicate that prenatal low level X-irradiation on the 9th or 17th day of gestation does not result in significant alterations in adult behavioural performance in the rat, but prenatal growth retardation persists postnatally. Growth may be a more sensitive indicator of the effects of prenatal exposure to X-radiation than postnatal behaviour.     

Prenatal diagnosis/treatment in families at risk for infants with steroid 21-hydroxylase deficiency (congenital adrenal hyperplasia)

The most common enzymatic defect of steroid synthesis is adrenal steroid 21-hydroxylase deficiency. Inhibited formation of cortisol causes increased pituitary release of ACTH, driving the adrenal cortex to overproduce androgens, whose synthesis does not involve the 21-hydroxylase enzyme. This hormonal setting is established in the embryonic period and affects development of genetic females, misdirecting differentiation of the external genitalia toward male type. At birth, the genitalia are visibly ambiguous (enlarged clitoris, fused labia) or in some cases even male in appearance {phallus with urethral opening, rugated scrotal sac), leading to wrong sex assignment. Adrenal steroid 21-hydroxylase deficiency is the most common basis of female pseudohermaphroditism. These females, however, have normal fertility and potential for gestation (gonads are functional and the internal duct-derived structures are well-formed), thus the sex of rearing should always be female. Management is by life-long hormonal (glucocorticoid) replacement, with surgical correction of the genital ambiguity. Prenatal diagnosis of 21-hydroxylase deficiency, first possible by steroid assay of the amniotic fluid, has utilized HLA typing for identification of loci (antigens B and DR) in close linkage with the 21-hydroxylase gene, and now increasingly relies on DNA analysis for linked HLA or C4 genes or for mutant 21-hydroxylase alleles directly by molecular genetic techniques. The most recent clinical advance is a program of combined prenatal diagnosis with karyotyping and suppression of fetal androgen production in genetic females by steroid administration to the mother. This is the first instance of an inborn metabolic error to be prenatally treated.

A series of 85 managed pregnancies is reported on, including accuracy of diagnosis, response of the mother to steroid treatment, and outcome for treated and untreated male and female fetuses (of 77 born by 6/91). Prenatal diagnosis by current techniques is accurate. Normal growth and development patterns postnatally suggest that dexamethasone treatment is safe.     

Specific morphogenetic events in mouse external genitalia sex differentiation are responsive/dependent upon androgens and/or estrogens

The objective of this study was to perform a comprehensive morphologic analysis of developing mouse external genitalia (ExG) and to determine specific sexual differentiation features that are responsive to androgens or estrogens. To eliminate sex steroid signaling postnatally, male and female mice were gonadectomized on the day of birth, and then injected intraperitoneally every other day with DES (200ng/g), DHT (1μg/g), or oil. On day-10 postnatal male and female ExG were dissected, fixed, embedded, serially sectioned and analyzed. We identified 10 sexually dimorphic anatomical features indicative of normal penile and clitoral differentiation in intact mice. Several (but not all) penile features were impaired or abolished as a result of neonatal castration. Those penile features remaining after neonatal castration were completely abolished with attendant clitoral development in androgen receptor (AR) mutant male mice (X(Tfm)/Y and X/Y AR-null) in which AR signaling is absent both pre- and postnatally. Administration of DHT to neonatally castrated males restored development of all 10 masculine features to almost normal levels. Neonatal ovariectomy of female mice had little effect on clitoral development, whereas treatment of ovariectomized female mice with DHT induced partial masculinization of the clitoris. Administration of DES to neonatally gonadectomized male and female mice elicited a spectrum of development abnormalities. These studies demonstrate that the presence or absence of androgen prenatally specifies penile versus clitoral identity. Differentiated penile features emerge postnatally and are sensitive to and dependent upon prenatal or pre- and postnatal androgen. Emergence of differentiated clitoral features occurs postnatally in either intact or ovariectomized females. It is likely that each penile and clitoral feature has a unique time-course of hormonal dependency/sensitivity.     

Effects of genistein in the maternal diet on reproductive development and spatial learning in male rats

Endocrine disruptors, chemicals that disturb the actions of endogenous hormones, have been implicated in birth defects associated with hormone-dependent development. Phytoestrogens are a class of endocrine disruptors found in plants. In the current study we examined the effects of exposure at various perinatal time periods to genistein, a soy phytoestrogen, on reproductive development and learning in male rats. Dams were fed genistein-containing (5 mg/kg feed) food during both gestation and lactation, during gestation only, during lactation only, or during neither period. Measures of reproductive development and body mass were taken in the male offspring during postnatal development, and learning and memory performance was assessed in adulthood. Genistein exposure via the maternal diet decreased body mass in the male offspring of dams fed genistein during both gestation and lactation, during lactation only, but not during gestation only. Genistein decreased anogenital distance when exposure was during both gestation and lactation, but there was no effect when exposure was limited to one of these time periods. Similarly, spatial learning in the Morris water maze was impaired in male rats exposed to genistein during both gestation and lactation, but not in rats exposed during only one of these time periods. There was no effect of genistein on cued or contextual fear conditioning. In summary, the data indicate that exposure to genistein through the maternal diet significantly impacts growth in male offspring if exposure is during lactation. The effects of genistein on reproductive development and spatial learning required exposure throughout the pre- and postnatal periods.     

Prenatal testosterone improves the spatial learning and memory by protein synthesis in different lobes of the brain in the male and female rat

The high density of the steroid hormone receptors in the structures of temporal lobe involved in learning and memory, such as the hippocampus, perirhinal cortex, entorhinal cortex and amigdaloid complex, shows that there must be a direct relationship between gonadal hormones and organizational effects of steroid hormones in those structures during development of the nervous system. The present study was undertaken in order to investigate the effect of testosterone administration during the third week of gestation on the spatial memory formation of the offspring rats and the level of soluble proteins in the temporal lobe and frontal lobe of brain, as evidence of important organizational effects of androgens during prenatal development in brain sexual dimorphism. Animals have received testosterone undecanoate on days 14, 15, 16 and 19, 20, 21 of gestation. Learning and memory tests were started 100 days after the testosterone treatment. At the end of the experiments, the temporal and frontal lobes of brain were removed for assessing the level of soluble proteins. Testosterone treatment significantly improved spontaneous alternations percentage of male offspring in Y-maze task comparative with female offspring and reference memory in radial 8 arm-maze task (decreasing in number of reference memory errors in both male and female offspring groups), suggesting effects of both short and long-term memory. Also, testosterone significantly increased the brain soluble protein level of treated female rats in 14–16 prenatal days compared with the control group as well as the brain soluble protein level of treated male rats. These results suggest that steroid hormones play an important role in the spatial learning and memory formation by means of protein synthesis in different lobes of the brain.     

Hypothalamic receptors of sex hormones in the mechanism of the sexual differentiation of the brain in rats

Studies have been made on the content of receptors of estradiol (E2) and testosterone (T) in cytoplasmic and nuclear fractions of the hypothalamus of male and female rats during neonatal development, as well as in adult females after androgenization in neonatal period and adult males castrated within 3 days of postnatal life. It was shown that both E2 and T are present in the blood serum of male and female newborn rats. In female hypothalamus, only E2 receptors were found, whereas in males both types of receptors were revealed, their content being higher than in females. In adult animals subjected to changes in the level of sex hormones in the blood during early neonatal period, changes in concentration of the receptors in the hypothalamic centres of regulation of tonic and cyclic secretion of gonadotropins were found. The data obtained presumably reveal the role of receptors of sex hormones in sex differentiation of the brain.     

Comparative Effects of Ethanol and Malnutrition on the Development of Catecholamine Neurons: Changes in Neurotransmitter Levels

Abstract: The comparative effects of exposure to ethanol and malnutrition on the concentrations of tyrosine and catecholamines in whole brain and selected regions of brain have been studied in the developing rat. These animals were the offspring of optimally nourished rats (control pups), of rats fed a diet with 35% of the calories supplied by ethanol (ETOH pups), or of animals fed a diet calorically equivalent to the latter but lacking ethanol (iso-caloric, 1C pups). These diets were administered to dams either during the last week of gestation (prenatal) or during lactation (postnatal). Tyrosine levels were elevated prior to birth in the prenatal ETOH or IC pups or at 1 and 2 weeks of age in postnatal ETOH or 1C pups as compared with values found in the control offspring. Dopamine concentration in whole brain was significantly lower in prenatal ETOH pups than in prenatal IC pups at 3 weeks of age. Levels in the brains of postnatal ETOH pups were lower than control values, but not relative to animals exposed to 1C diet. Investigation of corpus striatum showed a significant decrease in dopamine concentration compared with control or IC pup values as a result of postnatal exposure to ethanol. Norepinephrine levels in the whole brain of prenatal ETOH pups were consistently 30–40% lower than either control or matched 1C pups during development. At 3 weeks of age, the norepinephrine levels in the hypothalamus of animals exposed to ethanol pre or postnatally were 30–60% lower than values in the corresponding region in either control or 1C pups. In the rat model described, ethanol caused a decrease in catecholamine levels, perhaps solely by affecting the norepinephrine neurons.     

The role of neonatal androgen in the expression of hormonally induced maternal responsiveness in the adult rat

The role of neonatal androgen in the expression of hormonally induced maternal responsiveness in rats was investigated. Four to six hours postnatally male rats were either castrated or sham-castrated, while females were injected with testosterone propionate or oil, or were noninjected controls. When 90 days old the subjects were assigned either to a 21-day maternal hormone or to a vehicle regimen. Following these adult treatments subjects were tested for maternal responsiveness by means of a retrieving test in the home cage and in a T-maze. In the home cage test the adult hormone treatment caused a significant reduction in the time to sensitization in all neonatal treatment groups. In the T-maze only subjects with no androgen postnatally and with hormones in adulthood retrieved significantly more than their adult vehicle controls. It was concluded that the development of the potential to respond fully to the hormonal changes of pregnancy is inhibited by the postnatal presence of the male gonadal hormone.     

Neuroactive steroids in the brain and age and sex specificity of behavior and anxiety: An experimental study

Changes in the brain’s neuroactive steroid levels, behavior in the open field, and the anxious-phobic status of male and female rats in the course of development have been studied. An increase in the motor and exploratory activity and emotionality in rats of both sexes in the pubertal period and a decrease in their values in mature and old animals have been detected. Anxiety has no sexual dimorphism in adult animals; it is significantly higher in males than in females in the prepubertal and pubertal periods of development and is higher in old females than in males of the same age. An increase in the level of corticosterone in some brain structures in maturing and old rats has been found; the testosterone concentration increases in one-month-old and adult animals but decreases in old individuals, while the estradiol concentration in all studied brain structures of male and female rats was low in all periods of postnatal life. Correlation analysis has shown modulation by steroid hormones of the changes in behavioral responses during development.     

Leydig cell development

This review is about the study of the testis Leydig cells formation and development in prenatal and postnatal periods. Leydig cells of testis are the main place of synthesis and secretion of androgens including testosterone--the main male sexual hormone. Testosterone plays an important role in male reproduction regulation. There are two types (two populations) of Leydig cells during ontogenesis. The first type is fetal Leydig cells, which appear and function in the prenatal masculinization period of the male urogenital system. Another type is adult Leydig cells, which originate during sexual maturation postnatally. Fetal and adult Leydig cells pass the same stages both in the prenatal and postnatal periods. They are Leydig cell progenitors, immature Leydig cells and adult Leydig cells.     

Lordotic behavior in male rats: genetic and hormonal regulation of sexual differentiation

The male offspring of Long-Evans rats treated with the aromatization inhibitor ATD (1,4,6-androstatriene-3,17-dione) during pregnancy show high levels of lordotic behavior when treated with estrogen and progesterone in adulthood. The male offspring of Sprague-Dawley dams treated in the same way show only a slight facilitation of lordotic potential. These strain differences could reflect strain differences in gestation length and therefore differences in the timing of the sensitive period of sexual differentiation; they could reflect differences in the sensitivity to the defeminizing actions of gonadal hormones; or they could reflect differences in the sensitivity to ATD treatment. We therefore directly compared the effects of prenatal and early postnatal treatment with ATD on the potential of male Long-Evans and Sprague-Dawley rats to show lordosis when given estrogen and progesterone in adulthood. In both strains ATD treatment facilitated adult lordotic behavior. Treatment appeared to have a greater effect in the Long-Evans strain. However, control Long-Evans males were substantially more responsive to hormone treatment in adulthood than were Sprague-Dawley males. In the Long-Evans strain short-term ATD treatment (Days 20-23 of pregnancy) was as effective as long-term treatment (Days 10-23). In the Sprague-Dawley strain, ATD treatment was most effective when given prenatally and postnatally. Strain differences in hormonal sensitivity best account for the present findings.     

Sex differences in Seoul virus infection are not related to adult sex steroid concentrations in Norway rats

Field studies of hantavirus infection in rodents report that a higher percentage of infected individuals are males than females. To determine whether males were more susceptible to hantavirus infection than females, adult male and female Long Evans rats (Rattus norvegicus) were inoculated with doses of Seoul virus ranging from 10(-4) to 10(6) PFU. The 50% infective doses (ID(50)) were not significantly different for male and female rats (10(0.05) and 10(0.8) PFU, respectively). To determine whether sex differences in response to infection were related to circulating sex steroid hormones, sex steroid concentrations were manipulated and antibody responses and virus shedding were assessed following inoculation with the ID(90). Regardless of hormone treatment, males had higher anti-Seoul virus immunoglobulin G (IgG) and IgG2a (i.e., Th1) responses than females and IgG1 (i.e., Th2) responses similar to those of females. Males also shed virus in saliva and feces longer than females. Manipulation of sex steroids in adulthood did not alter immune responses or virus shedding, suggesting that sex steroids may organize adult responses to hantavirus earlier during ontogeny.