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PubMed1998

Prenatal gonadal steroids affect adult spatial behavior, CA1 and CA3 pyramidal cell morphology in rats.

The present study assessed whether prenatal androgen and estrogen exposure affected adult spatial learning and hippocampal morphology. Water maze performance, the CA1 and CA3 pyramidal cell field, and the dentate gyrus-granule cell layer (DG-GCL) morphology were assessed at adulthood (70+ days of age) in males, females, androgen-treated (testosterone propionate, TP, or dihydrotestosterone propionate, DHTP) females (2-4 mg/day), estradiol benzoate (EB)-treated females (100 microgram/day), and males treated with the antiandrogen flutamide (8 mg/day). Pregnant rats were injected daily (sc) between Embryonic Day 16 and birth; all pups were delivered by cesarean section. Flutamide-treated males were castrated upon delivery, and adult castrates were used to control for activational effects. Steroid-sensitive sex differences were observed in water maze performance in favor of males. Males had larger CA1 and CA3 pyramidal cell field volumes and soma sizes than females, which were feminized with flutamide treatment. TP and EB, but not DHTP, masculinized CA1 pyramidal cell field volume and neuronal soma size; CA3 was masculinized in both TP- and DHTP-treated females, while EB was ineffective. No effects were observed in cell density, number, or DG-GCL volume or due to adult hormone levels. Thus, prenatal androgens and estrogen influence sex differences in adult spatial navigation and exert differential effects on CA1 and CA3 pyramidal cell morphology. Hence, in addition to the previously reported postnatal component, there is also a prenatal component to the critical period in which gonadal steroids organize the neural mechanisms underlying sex differences in adult spatial ability.

Androgens↗
PubMed1999

Testosterone increases singing and aggression but not male-typical sexual partner preference in early estrogen treated female zebra finches.

Female zebra finches given estradiol benzoate (EB) as nestlings and testosterone propionate (TP) as adults show masculinized sexual partner preference, preferring females instead of males. This suggests an organizational effect of EB on sexual partner preference in a socially monogamous species that pairs for life. It is not known whether there is an activational hormone effect on sexual partner preference in this species, or whether adult testosterone treatment is necessary for masculinized preference to be expressed. In this experiment females were injected with EB daily for the first 2 weeks posthatching. As adults they were given TP filled or empty implants. Subjects were then given two-choice preference tests with male vs female stimuli, in which singing as well as proximity to the stimuli was recorded, followed by tests in a group aviary for social behavior and pairing preference. Females with TP implants sang more than females with empty implants and were more aggressive toward other females. They did not, however, differ from females with empty implants in any measure of sexual partner preference. Neither group showed a marked preference for males; instead both groups were equally interested in males and females. Thus adult testosterone treatment is not necessary for early estrogen treated females to show a shift in sexual partner preference in the male-typical direction.

Aggression↗
PubMed2002

Sexual experience interacts with steroid exposure to shape the partner preferences of rats.

A three-phase experiment manipulated sexual experience and hormone exposure (perinatally and in adulthood) in female rats housed individually from weaning so as to limit peripubertal social and sexual experience. Noncontact partner preference for a male or estrous female rat was measured both before and after sexual experience, first while rats were under the influence of circulating testosterone propionate (TP) and later after priming them with ovarian hormones (estradiol benzoate and progesterone; EB & P). When implanted with TP capsules and tested while sexually naive, all groups of female rats preferred females to males without differing statistically. However, following three sexual experience sessions with estrous females, differences emerged between the masculinized and control groups in the magnitude of their female-directed preference, with masculinized females demonstrating a significantly greater preference for estrous females. Sexual experience with male rats under EB & P did not result in a significant shift in preference in any group. Histological assessment indicated that the volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) was increased by exposure to TP postnatally, and SDN-POA volume correlated positively with partner preference scores but only when rats were both sexually experienced and exposed to circulating TP in adulthood. These results suggest that sexual experience interacts with steroid exposure to shape partner preference.

Animals↗
PubMed1998

Density-dependent prenatal androgen exposure as an endogenous mechanism for the generation of cycles in small mammal populations

Small mammal populations exhibit cyclic fluctuations in their population densities. Several hypotheses regarding the mechanisms underlying these population cycles have been advanced, but none has yet gained general approval. We propose here an endogenous mechanism based on the masculinization of female offspring in response to increased population levels. High population levels trigger the non-specific stress response resulting in high levels of circulating androgens in individuals of the population, including pregnant females. These androgens masculinize female offspring in utero, thereby reducing the reproductive capacity of the next generation and subsequently the population size. We have developed and analysed a mathematical model to investigate the possible role of prenatal androgen exposure in the generation of limit cycles. We find the locus of Hopf bifurcations for this model and show that limit cycles depend on three parameters: (1) the delay between birth and sexual maturation; (2) the slope of the function that relates average prenatal androgen exposure to total population density; and (3) the difference between the maximum birth rates of the low- and high-androgen exposed females. We derive the analytical form relating these parameters at the Hopf-bifurcation locus and discuss its biological ramifications. In brief, in each of these three parameters is sufficiently large, population cycles will results from the endogenous mechanism proposed.Copyright 1998 Academic Press Limited Copyright 1998 Academic Press Limited

Journal Article↗
PubMed2002

Granulin precursor gene: a sex steroid-inducible gene involved in sexual differentiation of the rat brain.

The mechanisms of sexual differentiation of the brain by sex steroids seem to be conserved throughout the mammalian species, although there may be some species differences. In rats, sex-dependent differentiation of the brain occurs in a sex steroid-dependent manner during the perinatal period known as the critical period. Androgen exposure during the perinatal period results in the development of structural and functional sexually dimorphic characteristics in the brain; the absence of testicular androgen leads the central nervous system to develop passively in a primarily female fashion, while the presence of androgen induces the masculinization of the brain. We attempted to characterize sex steroid-inducible genes that are involved in the sexually dimorphic function of the brain. Following the cDNA subtraction between hypothalami of 5-day-old intact and neonatally androgenized female rats, a granulin (grn) precursor gene was identified. The grn gene encodes a 6-kDa polypeptide known as a growth modulating factor of epithelial cells in vitro. Exogenous estrogen, as well as androgen, induced grn gene expression in the neonatal hypothalamus. In the brain of a 5-day-old male rat, grn mRNA was expressed in the ventromedial hypothalamic nucleus and the arcuate nucleus of the hypothalamus. Throughout the critical period for sexual differentiation of the brain, grn gene expression remained high in males, while in females it gradually decreased. Antisense oligodeoxynucleotide (ODN) complementary to grn mRNA was synthesized and infused into the third ventricle of male rats at 2 days of age. Two different control treatments were used; the first consisted of a control sequence ODN that had virtually no homology to known mRNAs, and the second consisted of vehicle alone. After maturation, the subject animals that were treated with antisense ODN of grn displayed significantly lower scores than the control males in various parameters assessing sexual behavior, i.e., mount, intromission, and ejaculation. The present results suggest that the grn gene, the expression of which is induced by sex steroids in the neonatal hypothalamus, plays a crucial role in the functional masculinization of the rat brain.

Animals↗
PubMed1975

Congenital adrenal hyperplasia. II. Cognitive and behavioral studies.

A sample of 31 patients with congenital adrenal hyperplasia was matched to a control group by sex, age, height, full-scale IQ score, and urban/rural site of residence. Patients and matched controls were tested on measures of masculinity and femininity and on sex-typed tests of cognitive ability. The two groups did not differ significantly on these measures. The finding is in disagreement with earlier reports of "masculinization" of behavior in female patients with congenital adrenal hyperplasia.

Adolescent↗
PubMed1995

Heterosexual and homosexual coercion, sexual orientation and sexual roles in medical students.

Rape has been conceptualized on a dimension of normal male behavior. The Koss and Oros (1982) study used a questionnaire that allowed men to respond only as sexual aggressors of women, and women only as victims of men. Medical students' responses to a modified questionnaire, in which both sexes reported being aggressors and/or victims, revealed that relatively comparable proportions of men and women were victims of coercive experiences: 35% of women and 30% of men experiencing constant physical attempts to have sexual activity. Forms of coercion not involving threat or use of force were more common, more exclusively heterosexual, and carried out by more equivalent percentages of men and women. 15% of women and 12% of men felt initially coerced into sexual activity but then enjoyed it. Threat or use of force to attempt to or to obtain intercourse were employed by 4% of men and 2% of women and experienced by 5% of both sexes. Half the male victims and female aggressors and a quarter of the male aggressors and female victims who reported such coercion stated it was homosexual. The ratio of homosexual/heterosexual feelings reported by male, but not female, students correlated with the degree of the homosexual coercion they both carried out and experienced. The degree of sexual coercion carried out by men and women correlated with their masculine sex role scores, suggesting, if the dimensional concept of rape is valid, that rape is on a continuum with masculine rather than male behaviors.

Adult↗
PubMed1976

Cultural factors affecting urban Mexican male homosexual behavior.

Some aspects of the mestizoized urban culture in Mexico are linked to male homosexuality in support of the theory that cultural factors play an important role in the kind of life styles and sex practices of males involved in homosexual behavior. The following factors are considered relevant: the sharp dichotomization of gender roles, dual categorization of females as good or bad, separate social networks maintained by males before and after marriage, proportion of unmarried males, and distribution of income. One result of the sharp dichotomization of male and female gender roles is the widely held belief that effeminate males generally prefer to play the female role rather than the male. Effeminacy and homosexuality are also linked by the belief that as a result of this role preference effeminate males are sexually interested only in masculine males with whom they play the passive sex role. The participation of masculine males in homosexual encounters is related in part to a relatively high level of sexual awareness in combination with the lack of stigmatization of the insertor sex role and in part to the restraints placed on alternative sexual outlets by available income and/or marital status. Males involved in homosexual behavior in Mexico operate in a sociocultural environment which gives rise to expectations that they should play either the insertee or insertor sex role but not both and that they should obtain ultimate sexual satisfaction with anal intercourse rather than fellatio. In spite of cultural imperatives, however, individual preferences stemming from other variables such as personality needs, sexual gratification, desires of wanted partners, and amount of involvement may override the imperatives with resulting variations in sexual behavior patterns.

Adolescent↗
PubMed1978

Psychological adjustment of homosexual and heterosexual men: a cross-national replication.

The present investigation of British subjects replicated an investigation conducted in the United States. There was considerable agreement in the findings of the two studies. A multidimensional evaluation of adjustment, based on questionnaire data, indicated that the total sample of British homosexuals described themselves as less well adjusted than the heterosexuals on four factors, better adjusted on two factors, and not different on six factors. There was a significant difference on only one dimension, however, for selected groups of masculine homosexuals vs. heterosexuals. Homosexuals and heterosexuals low on feminity, in addition, tended to be better adjusted than homosexuals and heterosexuals high on femininity. The possible confusion between adjustment and masculinity-femininity, as well as the importance of using a multidimensional approach when considering adjustment, is discussed.

Adaptation, Psychological↗
PubMed1980

Comparison of sex-typed motor behavior in male-to-female transsexuals and women.

Eight presurgical male-to-female transsexuals emitted significantly more feminine behaviors on a validated sex role motor behavior checklist than eight feminine women. Transsexuals also emitted more masculine behaviors than feminine women, although the total number of masculine behaviors in each group was far less than the total number of feminine behaviors. Indications for the management of transsexuals as well as the functions of sex role motor behavior in our society are discussed.

Adolescent↗
PubMed1992

Adult sexual orientation in relation to memories of childhood gender conforming and gender nonconforming behaviors.

Heterosexual, bisexual, and homosexual men recalled the extent to which they had engaged in gender conforming (masculine) and gender nonconforming (feminine) behaviors as a child. Adult sexual orientation was predicted as accurately by memories of childhood gender conforming behaviors as by memories of childhood gender nonconforming behaviors. However, childhood scripts as recalled by homosexual men were considerably more diverse. Twenty-two of 61 homosexual men reported having experienced few, if any, of the gender conforming behaviors and most, if not all, of the gender nonconforming behaviors. Another 18 homosexual men had the same profile of recalled childhood experiences as heterosexual men (high probability of masculine behaviors and low probability of feminine behaviors). Such diversity has implications not only for commentaries on the basis for homosexuality but for issues to be addressed in future research.

Adolescent↗
PubMed1992

Prenatal exposure to diethylstilbestrol (DES): childhood play behavior and adult gender-role behavior in women.

Data from lower mammals suggest a masculinizing or defeminizing influence of pre- or perinatal diethylstilbestrol (DES) exposure on various aspects of the sex-dimorphic behavior (including juvenile rough-and-tumble play) of genetic females. However, three previous studies on childhood play and adult gender-role behavior in human females have led to ambiguous results. In a follow-up study of 60 women with prenatal exposure to DES and 26 controls, we used psychometrically well-designed multi-item scales based on self-report inventories for the assessment of these aspects of behavior. No effects of DES could be demonstrated. We conclude that, at the doses studied, prenatal DES exposure in human females has not led to behavioral masculinization or defeminization of childhood play and adult gender-role behavior.

Adolescent↗
PubMed1985

Comparison of the effects of different isomers of bicuculline infused in the preoptic area on male rat sexual behavior.

Intracerebral infusion of (+) bicuculline methiodide, but not of its (-) isomer, in the preoptic area, stimulated masculine sexual behavior in rat as evidenced by a decrease in the number of intromissions preceding ejaculation and a shortening of the ejaculation latency and postejaculatory interval. Data suggest a role of the GABAergic system in mediating masculine sexual behavior.

Animals↗
PubMed2006

Exploring the association between anorexia nervosa and geographical latitude.

OBJECTIVE: This paper explores the relationship between anorexia nervosa (AN) and climate by mapping the distribution of references of AN in the literature at different latitudes. METHOD: The distributions of the bibliographic references of two medical disorders -psoriasis and cataracts-, and four mental disorders -AN, anxiety disorders, seasonal affective disorders, and schizophrenia- were mapped according to the institutional affiliation of their first author. RESULTS: The distribution of references to AN was quite similar to the mental and medical disorders associated to high latitudes, although references to AN were more frequent in the range of 40 masculine-55 masculine in the Northern Hemisphere. DISCUSSION: The psychosocial and sociocultural features of 'cultures' do not exhaust the factors defining the environment in which we live. Our findings indicate that climatic parameters, such as latitude may be a relevant factor in the occurrence of AN.

Anorexia Nervosa↗
PubMed2003

Low incidence of hip fractures in an equatorial area.

Hip fractures in patients older than 60 years of age represent a serious morbidity linked to osteoporosis that contributes to its mortality rates. Both genetic and environmental influences have been reported as important factors related to the epidemiology of osteoporosis. Sobral, a city located in the northeast (equatorial zone) of Brazil (3 masculine S/40 masculine E) has 138,565 inhabitants, who are mostly white Portuguese and native Brazilian descendants. We evaluated the occurrence of hip fractures in Sobral between July 1996 and June 2000. This was a retrospective cohort-based study. Data were obtained from the medical records of the Santa Casa de Sobral, which is the reference hospital in this area. All chart records of patients aged >20 years with a diagnosis of femoral or hip fracture were revised. A total of 79 fractures were identified. Ten cases (12.6%) that occurred in patients <50 years of age were excluded from further analysis. Sixty-nine cases (87.3%) occurred in patients aged >50 years, comprising 19 (27.5%) men and 50 (72.4%) women. This gives an age-adjusted annual incidence rate of 5.59/10,000 per year in men and 12.4/10,000 per year in women, respectively, for people >50 years of age. Two patients, aged 79 and 82, died 9 and 6 days, respectively, after hospital admission. The average time of hospitalization was 7.5 days (range 4-19 days). As expected, there was a significant rise in hip fractures in people >50 years old. Interestingly, the hip fracture rate in this population is considerably lower (around 4 times less) than the reported rates in white Caucasians.

Adult↗
PubMed2006

Unicompartmental versus computer-assisted total knee replacement for medial compartment knee arthritis: a matched paired study.

Patients older than 60 with unicompartmental knee arthritis can be treated with total or unicompartmental knee replacement. The aim of this study was to compare the results of matched paired groups of patients with isolated medial compartment knee arthritis replaced with either UKR (group A) or computer-assisted TKR (group B). The results included 68 knees at a minimum follow-up of 3 years. All patients had a varus deformity no greater than 8 masculine and a BMI lower than 30. Patients were matched in terms of preoperative arthritis severity, age, gender and preoperative range of motion. In the computer-assisted TKR group, all the implants were positioned within 4 masculine of the correct hip-knee-ankle angle and frontal tibial component angle. The surgical time and hospital stay were statistically longer in the CA TKR group. During the study no implant required revision. The results showed higher scores for a UKR in the treatment of isolated primary unicompartmental knee arthritis in patients older than 60 compared to a computer-assisted TKR. In this study a computer-assisted alignment system for TKR with optimal implant positioning did not produce equivalent clinical results compared to a UKR, but did increase the financial costs.

Aged↗
PubMedDate not supplied

Circumareolar mastectomy in female-to-male transsexuals and large gynecomastias: a personal approach.

Breast reduction or amputation in female-to-male surgery presents a specific surgical problem: obtaining a good breast shape of the masculine type. Over a 2-year period, 17 patients (12 female-to-male transsexuals and 5 extreme gynecomastias) were operated on using the circumareolar approach for subcutaneous mastectomy. The nipple-areola complex was left on a very wide deepithelialized dermal pedicle, and the final closure of the wound was performed using a round-block technique followed by numerous fine sutures to reduce wrinkling. This technique provides naturally flat masculine breasts, leaving sufficient dermal vascularization for the nipple-areola complex which is of the utmost importance. All the patients were very satisfied with the result because of the periareolar scar only. Two areolar necroses occurred due to perforation of the thin vascular dermal pedicle: one superficial which epithelialized spontaneously in a short period of time and one deeper which required skin grafting.

Adult↗
PubMed2007

[Cyclorotation of the eye in wavefront-guided LASIK using a static eyetracker with iris recognition].

PURPOSE: Centration of the ablation zone decisively influences the result of wavefront-guided LASIK. Cyclorotation of the eye occurs as the patient changes from the sitting position during aberrometry to the supine position during laser surgery and may lead to induction of lower and higher order aberrations. METHODS: Twenty patients (40 eyes) underwent wavefront-guided LASIK (B&L 217z 100 excimer laser) with a static eyetracker driven by iris recognition (mean preoperative SE: -4.72+/-1.45 D; range: -1.63 to -7.00 D). The iris patterns of the patients' eyes were memorized during aberrometry and after flap creation. RESULTS: The mean absolute value of the measured cyclorotation was -1.5+/-4.2 degrees (range: -11.0 to 6.9 degrees ). The mean cyclorotation was 3.5+/-2.7 masculine (range: 0.1 to 11.0 degrees ). In 65% of all eyes cyclorotation was >2 masculine. CONCLUSIONS: A static eyetracker driven by iris recognition demonstrated that cyclorotation of up to 11 degrees may occur in myopic and myopic astigmatic eyes when changing from a sitting to a supine position. Use of static eyetrackers with iris recognition may provide a more precise positioning of the ablation profile as they detect and compensate cyclorotation.

Adult↗