Female Puberty Research Articles

Puberty-Related Changes in Cortisol, Dehydroepiandrosterone, and Estradiol-17β Secretions within the First Hour after Waking in Premenarcheal Girls

Objective: The onset of menstruation is the hallmark of female pubertal development. The present study determined whether pubertal girls experience adrenocortical and ovarian steroid secretions within their first waking hour before getting their period, similar to those observed in adult females with regular cycles. Methods: Cortisol, dehydroepiandrosterone (DHEA), and estradiol-17β concentrations were measured in saliva samples collected after awakening (0, 30, and 60 min after awakening) from 158 normal premenarcheal pubertal girls and 69 adult females with regular menstrual cycles. The girls were subgrouped according to self-reported Tanner breast (B) and pubic hair (PH) stages (B1PH1, B2PH1, B2PH2, B3PH1, and B3PH2). Results: All the subgroups showed a similar pattern of cortisol secretion. However, cortisol levels were higher in girls at B3PH1 and at B3PH2 than other subgroups. DHEA secretion showed a similar pattern across the groups examined. The largest increase in DHEA levels occurred between B1PH1 and B2PH1 stages, and further increased with pubertal progression. DHEA levels in girls at B3PH2 were approximately one half of the adult value. Estradiol-17β profiles in girls at B3PH1 and B3PH2 differed from those of other subgroups of girl. A sharp increase in estradiol-17β levels after awakening which observed in adult females emerged in girls at B3PH1 and B3PH2. However, the estradiol-17β levels did not reach adult values until B3PH2 stage. Conclusions: The progression of female puberty includes an increase in the levels of adrenocortical and ovarian steroid secretions and a gain of adult female-like patterns of estradiol-17β secretion within their first waking hour.

English

BACKGROUND: Menarche is most striking event in process of female puberty. Some girls seek medical attention for normal cycle variation. Others are unaware that their bleeding patterns are abnormal and may be attributable to significant underlying medical issues. Menstrual cycle, as a vital sign serves a powerful tool to assess normal development and to exclude pathologies. AIM: To find out age of menarche, menstrual pattern and types of menstrual disorders. METHOD: A cross sectional study was conducted among 80 nursing students of nursing college, linked with Peoples college of Medical Sciences and Research centre, Bhopal. All girls in study group were below 19 years of age. Information was obtained in a self-administered proforma after verbal consent. Questionnaire was analyzed by subject expert & statistical analyst. RESULTS: Mean age of menarche in this study was 11 years, 40% have regular cycle. Mean duration of bleeding was 4-6days.Day of heaviest flow was day 2 in 60%. Menstrual cycle was of 25 -45 days. Dysmenorrhoea was present in 40% of adolescent girls. 30% had dysmenorrhea since menarche. 30% had premenstrual symptoms. The most common premenstrual symptom was general fatigue in 46%. Absence from the college was observed in 20%. 40% girls taken menstruation as normal phenomenon. 78% had discussed menstrual problems with someone, most commonly with their peers. CONCLUSION: Pattern of menstrual bleeding in all adolescent girls in order to identify possible pathology and to improve their quality of life should be assessed routinely.

Feeding prepubescent gilts a high-fat diet induces molecular changes in the hypothalamus-pituitary-gonadal axis and predicts early timing of puberty

ObjectiveThe onset of puberty in females has been occurring earlier over the past decades, presumably as a result of improved nutrition in developed countries. However, the underlying molecular mechanisms responsible for the early attainment of puberty as a result of nutrition fortification remain largely unknown. The aim of this study was to evaluate the hormone and gene expression changes in prepubescent gilts fed a high-fat diet to investigate whether these changes could predict the early timing of puberty. MethodsForty gilts were fed a daily basal diet (LE) or a basal diet with an additional 270 g/d or 340 g/d of fat (HE) during the prepubescent phase. Blood samples were collected during the prepubescent phase to detect hormone secretion changes in insulin-like growth factor-1, kisspeptin, estradiol, progesterone, and leptin. The gene expressions at the hypothalamus–pituitary–gonadal axis were examined on day 73 of the experiment (average age on day 177) during the prepubescent phase. ResultsAn HE diet resulted in accelerated body weight gain and back-fat thickness at the P2 point compared with LE gilts during the prepubescent phase. Gilts that were fed HE diets attained puberty 12 d earlier than LE gilts, and a larger proportion of HE gilts reached puberty at day 180 or 190 of age. A postmortem analysis revealed a promoted development of the uterus and ovary tissue that was characterized by a 53.7% and 29.5% increase in the uterine and ovary weight, respectively, and an increased length of the uterine horn and oviduct tissue in HE gilts. Real-time quantitative polymerase chain reaction revealed that HE gilts had higher Kiss-1, G protein-coupled receptor 54, gonadotropin-releasing hormone and estrogen receptor α mRNA expression levels in the hypothalamic anteroventral periventricular nucleus; the leptin receptor mRNA expression level was higher in the hypothalamic arcuate nucleus and ovary tissue; the insulin-like growth factor-1 receptor expression was higher in the pituitary and ovary tissues, and the follicle-stimulating hormone and luteinizing hormone mRNA expression levels were higher in the pituitary gland. ConclusionThese data showed that the consumption of additional fat can facilitate early attainment of puberty, which can be predicted by the changes in secreted hormones and gene expression in the hypothalamus-pituitary-gonadal axis.

Postweaning dietary genistein exposure advances puberty without significantly affecting early pregnancy in C57BL/6J female mice

An epidemiological study indicates higher plasma level of genistein in girls with earlier puberty. This study tests the hypothesis in C57BL/6J mice that postweaning (peripubertal) dietary genistein exposure could result in earlier puberty in females assessed by vaginal opening, estrous cyclicity, corpus luteum and mammary gland development. Newly weaned female mice were fed with 0, 5, 100, or 500ppm genistein diets. Decreased age at vaginal opening, increased length on estrus stage, and accelerated mammary gland development were detected in 100 and 500ppm genistein-treated groups. Increased presence of corpus luteum was found in 5ppm genistein-treated group at 6 weeks old only. Increased expression of epithelial-specific genes but not that of ERα or ERβ was detected in 500ppm genistein-treated mammary glands at 5 weeks old. No significant adverse effect on embryo implantation was observed. These data demonstrate causal effect of dietary genistein on earlier puberty in female mice.

Peripubertal exposure to male odors influences female puberty and adult expression of male-directed odor preference in mice

Testosterone-dependent olfactory signals emitted by male are well known to accelerate female puberty in mice (Vandenbergh effect). However, it remains unclear whether these chemosignals also influence adult expression of male-directed odor preference. Therefore, we exposed female mice to intact or castrated male bedding (vs clean bedding as control) during the peripubertal period (postnatal day (PD) 21–38) and measured male-directed odor preference in adulthood. At PD45 or PD60, females exposed to intact male odors, and thus showing puberty acceleration, preferred to investigate odors from intact males over females or castrated males. Females exposed to castrated male odors did not show puberty acceleration but preferred male (intact or castrated) over female odors. Finally, control females did not show any odor preference when tested at PD45, although a preference for male odors emerged later (PD60). In a second experiment, females that were exposed to intact male odors after pubertal transition (PD36–53) also preferred intact male over castrated male odors. In conclusion, our results indicate that peripubertal exposure to male odors induced early expression of male-directed odor preference regardless of puberty-accelerating effect and that induction of male-directed odor preference is not specific to the peripubertal period.

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Introduction: Published reference values for cardiac (SV/SVI/CO/CI) and vascular (SVR/SVRI) parameters agree closely, but rely on small series of measurements using dissimilar measurement technologies. Agreement between different methods is hotly debated. Changes from birth to maturity and from maturity to death are poorly defined. This study combined large unpublished data sets using noninvasive BP and CW Doppler (USCOM, Sydney, Au) measurement to define the change in arterial pressure, stroke volume and “resistance” between birth and advanced age. Methods: Noninvasive hemodynamic values for SV/SVI,CO/CI and MAP were obtained from 2507 subjects by Noninvasive BP cuff and CW Doppler using the USCOM device (Sydney,Au): 876 females and 975 males under 20 years of age were examined using the USCOM monitor for progressive change in SV, SVI, MAP, CO, CI and R. 382 adult female subjects from 20 to 94 and 273 adult males from 20–97 years were analyzed using USCOM. Vascular resistance was calculated as the ratio of (MAP-CVP)/SV, and expressed as mm.Hg/L. CVP was assumed to be zero. Results: Noninvasive mean arterial pressure at the beginning of life was ca. 60 mm Hg, and reached 80 mm Hg at puberty in males and females; it increased with every year of age, reaching 100 mm Hg at around 70 years of age. Resting Stroke Volume increased linearly in girls and plateaud between 10–12 years, and then remained unchanged until around 70 years, when it declined progressively each year. In boys, the resting SV increased linearly and plateaud at 12–14 years. It remained essentially constant until around 80 years, when it progressively declined. Resistance in the circulation was 3000–4000 mm.Hg/L at birth in males and females and decreased progressively until it reached a “vertical plateau” at puberty. It rose from 70 years in females and 80 years in males. Conclusions: There are 3 distinct phases in pressure regulation from birth to old age. The plateau phase between 12 and 70 years in females and 14 to 80 in males implies endocrine control of the circulation. Indexing values to body surface area shows a progressive fall in SVI from 12 in girls and 14 yrs in boys, and continues throughout life. The occurrence of a upper inflection point in the elderly, characterized by rising resistance and falling SV, may suggest that cardiovascular death is unavoidable in the very elderly and represents programmed somatic death. Larger numbers of elderly subjects are required to clarify the pattern of change at the end of life.

Indigenous sheep breeds of North Ethiopia: characterization of their phenotype and major production system

A study was conducted in Tigrai, Northern Ethiopia to describe the sheep breeds and their production system. The survey was done in selected districts known for their high sheep population density. The phenotype characterization identified distinct features for each breed. The breeds are Aberegelle, Ille, Begait, and the common Tigrai highland sheep. The strong discriminating phenotypes are face profile, tail type, and compactness; accounting for 83.48, 17.95, and 2.93% respectively of the total variability among breeds. The flock structure are affected by the market demand; requirements of breeding females and feed availability. Farmers tend to keep more female sheep for longer (culling age of 5.9 ± 0.4 and 1.9 ± 0.5 for females and males, respectively) for the reasons of feed shortage and need to maximize number of breeding female. The ratio of male to overall female is large (1:6) and thus a single ram gets maximum contact time with ewes and ewe lambs. The overall average age at puberty for females is 9-14 months. However, the presence of very young lamb rams and uncontrolled mating system lead to early breeding of females which results in low conception rate, low birth weight, poor survival rates, and in extreme cases causing inbreeding. It was also possible to identify the critical control points such as breed, age of animals, nutrition, and feeding systems affecting the provision of live animals for good meat quality.

Agouti-related peptide plays a critical role in leptin's effects on female puberty and reproduction

Deficient leptin signaling causes infertility via reduced activity of GnRH neurons, causing a hypogonadal state in both rodents and humans. Because GnRH neurons do not express leptin receptors, leptin's effect on GnRH neurons must be indirect. Neurons within the hypothalamic arcuate nucleus that coexpress AGRP and NPY are considered to be important intermediate neurons involved in leptin regulation of GnRH neurons. Previously, we reported that the absence of AGRP and haploinsufficiency of MC4R in leptin receptor mutant (Lepr(db/db)) females result in restoration of fertility and lactation despite the persistence of obesity and insulin resistance. The overarching hypothesis in the present study is that the absence or reduction of leptin's inhibition of AGRP/NPY neurons leads to suppression of GnRH release in cases of leptin signaling deficiency. Since TAC2 (NKB)-TAC3R signaling plays a role in puberty maturation and is modulated by metabolic status, the other aim of this study is to test whether TAC2/NKB neurons in ARC regulated by melanocortinergic signals herein affect leptin's action on puberty and reproduction. Our data showed that AGRP deficiency in Lepr(db/db) females restores normal timing of vaginal opening and estrous cycling, although uterine weight gain and mammary gland development are morphologically delayed. Nonetheless, Agrp(-/-) Lepr(db/db) females are fertile and sustain adequate nutrition of pups with lactation to weaning age. AGRP deficiency results in advanced vaginal opening in wild-type female mice. The postpubertal increase in hypothalamic TAC2 mRNA was not observed in Lepr(db/db) females, whereas AGRP deficiency restored it in Lepr(db/db) females. Additionally, MC4R activation with MTII induced FOS expression in TAC2 neurons, supporting the concept of melanocortinergic regulation of TAC2 neurons. These studies suggest that AGRP imposes an inhibitory effect on puberty and that TAC2 neurons may transmit melanocortinergic inhibition of GnRH neurons.

The association of vitamin D status with cardiometabolic risk factors, obesity and puberty in children

Low serum 25-hydroxyvitamin D3 (25(OH)D) levels have been associated with insulin resistance and cardiovascular diseases. The influences of gender, puberty and adiposity on vitamin D status and the relationship between 25(OH)D and cardiometabolic risk factors in obese and non-obese children were studied. A retrospective analysis was carried out on 168 Turkish children during late winter. Age, gender, puberty, body mass index (BMI), 25(OH)D levels and cardiometabolic risk factors including lipid profiles, high-sensitivity C-reactive protein and insulin resistance index calculated by homeostasis model assessment (HOMA-IR) were evaluated. The median age of the study population was 11 (4-16) years, and 102 children (60.7 %) were prepubertal. Overall, 98.2 % of patients had 25(OH)D levels lower than 20 ng/mL (median 10.0 (4.0-21.3) ng/mL). The 25(OH)D levels did not correlate with BMI. However, an inverse correlation was seen between serum 25(OH)D and HOMA-IR (rho = -0.656, p = 0.006) and insulin (rho = -0.715, p = 0.002) in pubertal obese subjects. Female gender and puberty were all negatively associated with 25(OH)D. The association between vitamin D status and BMI is complex, and it does not seem to be altered by mild obesity. In addition, potential influence of puberty should be kept in mind while assessing the relationship between serum 25(OH)D and cardiometabolic risk factors.

Genetic dissection of puberty in mice

Determining the neural mechanisms controlling gonadotrophin-releasing hormone (GnRH) release is of pivotal importance in understanding central control of reproductive physiology in vertebrates. Targeted genetic manipulation of kisspeptin and GPR54 neurons has provided new insights into the mechanisms modulating GnRH release and thereby regulating hypothalamic-pituitary-gonadal axis activity during reproductive maturation. While conditional ablation of the oestrogen receptor α gene in kisspeptin neurons results in a dramatic advancement of the onset of puberty in female mice, subsequent pubertal maturation is arrested in these animals, as they fail to acquire normal ovulatory cyclicity. These data suggest that two oestrogen receptor α-dependent mechanisms, one a 'brake' and the other an 'accelerator', are sequentially operated in kisspeptin neurons during pubertal development of female mice to gate and then to activate GnRH release. In a different experimental approach, we removed entire kisspeptin neurons from the mouse brain and thus from the neural circuits controlling reproduction. Surprisingly, the onset of puberty in females was unaffected by kisspeptin neuron ablation. Furthermore, the animals attained regular ovulatory cyclicity and were fertile. Consistent with this, female mice lacking neurons that express the kisspeptin receptor GPR54 were also fertile, suggesting female reproductive maturation in the absence of kisspeptin/GPR54 signalling. However, acute kisspeptin neuron ablation in adult mice inhibited fertility, indicating that there is developmental compensation for the loss of kisspeptin neurons during reproductive neural circuit formation. Finally, we showed that kisspeptin neurons become an indispensable part of reproductive neural circuitry in the mouse brain before postnatal day 20.

Comprehensive Assessment of a Chlorinated Drinking Water Concentrate in a Rat Multigenerational Reproductive Toxicity Study

Some epidemiological studies report associations between drinking water disinfection byproducts (DBPs) and adverse reproductive/developmental effects, e.g., low birth weight, spontaneous abortion, stillbirth, and birth defects. Using a multigenerational rat bioassay, we evaluated an environmentally relevant "whole" mixture of DBPs representative of chlorinated drinking water, including unidentified DBPs as well as realistic proportions of known DBPs at low-toxicity concentrations. Source water from a water utility was concentrated 136-fold, chlorinated, and provided as drinking water to Sprague-Dawley rats. Timed-pregnant females (P0 generation) were exposed during gestation and lactation. Weanlings (F1 generation) continued exposures and were bred to produce an F2 generation. Large sample sizes enhanced statistical power, particularly for pup weight and prenatal loss. No adverse effects were observed for pup weight, prenatal loss, pregnancy rate, gestation length, puberty onset in males, growth, estrous cycles, hormone levels, immunological end points, and most neurobehavioral end points. Significant, albeit slight, effects included delayed puberty for F1 females, reduced caput epidydimal sperm counts in F1 adult males, and increased incidences of thyroid follicular cell hypertrophy in adult females. These results highlight areas for future research, while the largely negative findings, particularly for pup weight and prenatal loss, are notable.

Intra-pituitary relationship of follicle stimulating hormone and luteinizing hormone during pubertal development in Atlantic bluefin tuna (Thunnus thynnus)

As part of the endeavor aiming at the domestication of Atlantic bluefin tuna (BFT; Thunnus thynnus), first sexual maturity in captivity was studied by documenting its occurrence and by characterizing the key hormones of the reproductive axis: follicle stimulating hormone (FSH) and luteinizing hormone (LH). The full length sequence encoding for the related hormone β-subunits, bftFSHβ and bftLHβ, were determined, revealing two bftFSHβ mRNA variants, differing in their 5′ untranslated region.A quantitative immuno-dot-blot assay to measure pituitary FSH content in BFT was developed and validated enabling, for the first time in this species, data sets for both LH and FSH to be compared. The expression and accumulation patterns of LH in the pituitary showed a steady increase of this hormone, concomitant with fish age, reaching higher levels in adult females compared to males of the same age class. Conversely, the pituitary FSH levels were elevated only in 2Y and adult fish. The pituitary FSH to LH ratio was consistently higher (>1) in immature than in maturing or pubertal fish, resembling the situation in mammals. Nevertheless, the results suggest that a rise in the LH storage level above a minimum threshold may be an indicator of the onset of puberty in BFT females. The higher pituitary LH levels in adult females over males may further support this notion.In contrast three year-old (3Y) males were pubertal while cognate females were still immature. However, it is not yet clear whether the advanced puberty in the 3Y males was a general feature typifying wild BFT populations or was induced by the culture conditions. Future studies testing the effects of captivity and hormonal treatments on precocious maturity may allow for improved handling of this species in a controlled environment which would lead to more cost-efficient farming.

Phthalates may promote female puberty by increasing kisspeptin activity

Is there an association between exposure to phthalates and the timing of female puberty? Our study suggests that the early onset of puberty is related to increased kisspeptin secretion. Girls are maturing earlier than in past decades and the quantity of phthalates used in consumer products has concurrently risen. The hypothesis that exposure to phthalates may increase kisspeptin secretion and thereby cause early-onset puberty is unexplored. This case-control study ran from 2006 to 2009. We enrolled 104 girls. Girls in the central precocious puberty (CPP) (case) group were recruited from a pediatric endocrinology policlinic in Taiwan; prepubescent controls were recruited from local elementary schools and all were categorized based on a pediatrician's diagnosis. The physical characteristics of puberty were assessed and levels of LH, FSH estradiol and kisspeptin-54 in blood samples were evaluated using radioimmunoassay. Reversed-phase high-performance liquid chromatography-tandem mass spectrometry was used to analyze seven urinary phthalate metabolites. Non-parametric analyses, trend tests and linear regressions were performed on the data. All seven urinary phthalate metabolites in the CPP group were significantly (P < 0.05) higher than in prepubescent controls. Serum kisspeptin-54 levels were higher (P = 0.022) in the CPP group than controls and were still significantly higher after adjusting for age (P = 0.03). There was a significant increasing trend (P(trend) = 0.005) between levels of kisspeptin and the stages of puberty. The concentration of kisspeptin-54 did not change in girls treated with leuprorelin acetate. There was a significant positive correlation between kisspeptin-54 and urinary mono-n-butyl phthalate (ng/ml: R(2) = 0.251, P < 0.001; μg/g-creatinine: R(2) = 0.109, P = 0.024). The study duration was short and the sample size relatively small; therefore, we were unable to collect sufficient evidence to support the temporality between exposure to phthalates and the subsequent occurrence of PP. Kisspeptin may promote the onset of puberty in girls who are exposed to a high level of phthalates, especially di-n-butyl phthalate. These data suggest that developing a kisspeptin antagonist might be an alternative strategy for treating PP. This work was supported by grants NSC 96-2621-Z-006-013 and NSC 97-2621-M-006-001 from the Taiwan National Science Council. The authors have no conflicts of interest to disclose.

Long-term programming of enhanced aggression by peripuberty stress in female rats

Human literature has linked adverse early life experiences with an increased risk to develop violent behaviors in both boys and girls. We have previously shown that male rats submitted to stress during the peripuberty period display as adults abnormal aggressive behavior against both male intruders and female partners. In the present study, we examined whether the same stress protocol would affect the development of aggressive behaviors in female rats. We evaluated the behavior of these peripuberty stressed female rats when confronted, at adulthood, with either female or male intruders, and during their cohabitation with male partners. Given that estrus cycle influences mood and aggressive behaviors, female aggressive behavior was assessed at different estrus cycle phases: estrus and diestrus, and during pregnancy and lactancy. Additionally, we evaluated postpartum plasma levels of vasopressin, oxytocin and corticosterone, hormones associated with aggression and the regulation of social behavior. Compared to control females, females submitted to stressful events during puberty exhibited higher and more sustained rates of aggression during adulthood independently on the estrus cycle or the sex of the intruder, and they had higher levels of plasma vasopressin. Significant correlations between plasma levels of vasopressin and corticosterone and aggressive behavior were also found. Strikingly, our results showed opposite intragroup correlations suggesting a different role of these hormones on aggression depending on life experiences. We provide here an animal model, devoid of cultural influences strongly supporting a role for biological factors in the development of aggressive behaviors following exposure to stressful events at puberty in females.

Evidence for pleiotropism and recent selection in the PLAG1 region in Australian Beef cattle

A putative functional mutation (rs109231213) near PLAG1 (BTA14) associated with stature was studied in beef cattle. Data from 8199 Bos taurus, Bos indicus and Tropical Composite cattle were used to test the associations between rs109231213 and various phenotypes. Further, 23496 SNPs located on BTA14 were tested for association with these phenotypes, both independently and fitted together with rs109231213. The C allele of rs109231213 significantly increased hip height, weight, net food intake, age at puberty in males and females and decreased IGF-I concentration in blood and fat depth. When rs109231213 was fitted as a fixed effect in the model, there was an overall reduction in associations between other SNPs and these traits but some SNPs remained associated (P<10(-4) ). Frequency of the mutant C allele of rs109231213 differed among B.indicus (0.52), B.taurus (0.96) and Tropical Composite (0.68). Most chromosomes carrying the C allele had the same surrounding 10 SNP haplotype, probably because the C allele was introgressed into Brahman from B.taurus cattle. A region of reduced heterozygosity surrounds the C allele; this is small in B.taurus but 20Mb long in Brahmans, indicating recent and strong selection for the mutant allele. Thus, the C allele appears to mark a mutation that has been selected almost to fixation in the B.taurus breeds studied here and introduced into Brahman cattle during grading up and selected to a frequency of 0.52 despite its negative effects on fertility.

Female pubertal timing and problem behaviour

We tested the peer-socialization/contextual-amplification explanation for the link between early female puberty and problem behaviour. We propose that in cultures with high tolerance for adolescent heterosexual involvement, early puberty should be linked with problem behaviour—not in other cultures. We compared girls in two cultures (Slovakia and Sweden) that differ in acceptance of adolescent girls’ heterosexual involvement. Findings supported the hypothesis by showing that in Sweden, a culture that facilitates adolescent heterosexual involvement, early-maturing girls reported more problem behaviours than in Slovakia. The mediation link (heterosexual involvement as the mechanism linking early puberty with problem behaviour) was moderated by culture. The findings expand our understanding of the role of macro-cultural contexts in the developmental significance of female puberty.

Metabolic Programming of Puberty: Sexually Dimorphic Responses to Early Nutritional Challenges

Body energy stores and metabolic cues influence the onset of puberty. However, the pubertal impact of early nutritional challenges has been only fragmentarily addressed. We evaluated here the consequences, in terms of pubertal timing and hormonal markers, of various nutritional manipulations during pre- or postnatal maturation in rats of both sexes. Males and females were submitted to gestational undernutrition (UNG) or peripubertal (SUB) subnutrition or were raised in large (LL; underfeeding) or small (SL; overfeeding) litters. In addition, groups of UNG, LL, and SL rats were fed on a high-fat diet (HFD) after weaning. Postnatal overfeeding resulted in higher body weights (BWs) during pubertal transition in both sexes, but only SL males displayed overtly advanced external signs of puberty. Postnatal underfeeding persistently decreased BW gain during puberty, yet the magnitude of pubertal delay was greater in LL males. In contrast, regardless of postnatal nutrition, HFD tended to advance the onset of puberty in females but did not alter pubertal timing in males. Likewise, SUB females displayed a marked delay in BW gain and puberty onset, whereas despite similar reduction in BW, SUB males showed normal timing of puberty. These sex divergences were also detected in various hormonal and metabolic indices so that postnatal overnutrition consistently increased LH, FSH, leptin, and insulin levels only in pubertal females, whereas HFD decreased gonadotropin levels in SL females but increased them in SL males. Notably, UNG rats did not show signs of delayed puberty but displayed a striking sex dimorphism in serum insulin/glucose levels, regardless of the diet, so that only UNG males had signs of presumable insulin resistance. Our data disclose important sex differences in the impact of various early nutritional challenges on the timing of puberty, which may help to explain the different trends of altered puberty and related comorbidities between sexes.

Substituição parcial do milho por sorgo granífero na alimentação de matrizes suínas primíparas nos períodos de puberdade e gestação

Avaliou-se o efeito da substituição parcial do milho por sorgo granífero na dieta de matrizes suínas híbridas durante a puberdade e a gestação. Foram utilizadas 25 leitoas, distribuídas em três tratamentos com porcentagens crescentes de sorgo granífero - 0%, 25% e 50% - em substituição ao milho. As fêmeas foram avaliadas durante as fases de pré-puberdade, puberdade e gestação, tendo sido mensurados o peso vivo (PV) e a idade à puberdade nas jovens e o PV e a espessura de toucinho (ET) nas fêmeas gestantes - à cobrição e aos 30, 60, 90 e 110 dias de prenhez. Na fase de pré-puberdade, o ganho de peso diário diminuiu com o aumento da utilização do sorgo, e durante a puberdade não houve efeito dos tratamentos. Houve efeito linear da substituição sobre o PV aos 90 dias de gestação. Nos demais períodos, não foram encontrados efeitos significativos. Conclui-se que o sorgo granífero pode substituir o milho em até 50% na dieta de fêmeas suínas durante a puberdade e a gestação, sem comprometer as variáveis produtivas e reprodutivas.

Gonad differentiation and puberty onset in the zebrafish: Evidence for the dependence of puberty onset on body growth but not age in females

Puberty is the period in the vertebrate life cycle that marks the transition from sexual immaturity to maturity, enabling an animal to acquire adult reproductive functions. Puberty, an important point in vertebrate reproductive life, has been under extensive study in the past decades. It has been known for a long time that the initiation of puberty in mammals is closely associated with body growth and metabolism; however, there has been no equivalent report in small model teleosts such as the zebrafish. Using morphological and histological analysis, this study was undertaken to examine the timing of gonad differentiation and female maturation (puberty) in the zebrafish, with particular emphasis on the potential impact of body growth on the onset of puberty. Our data showed that gonad differentiation in the zebrafish completed around 35 days post-fertilization (dpf) in females and 45 dpf in males. Puberty in females is initiated at around 45 dpf. Our experiments provided clear evidence that the initiation of puberty in female zebrafish was strongly correlated with body size but not age, supporting the importance of the growth axis in the onset of puberty. This study provides essential information on basic characteristics of growth and reproduction in zebrafish.

Supporting young women with oligomenorrhea

The onset of menarche can be a difficult time for adolescent girls. Oligomenorrhea is a type of menstrual irregularity which can present among young women. It consists of menses that occur at intervals that are longer than 35 days. School nurses can play an important role in providing information and advice on the condition. This article is part of a series looking at male and female puberty issues, it provides an overview of oligomenorrhea, including causes, symptoms and treatment.