Reproductive parameters of Oreochromis mossambicus in Laguna de Los Patos, Cumaná, Venezuela.

A total of 381 specimens of the tilapia Oreochromis mossambicus collected monthly from May 2017 to May 2018 in the Laguna de Los Patos, Cumaná, Venezuela, to evaluate reproductive parameters of this non-native species. Significant differences were found in relation to average height and weight between males and females, with the highest values in males. The sex ratio was 1:1.5 (males:females), which deviates significantly from the expected 1:1 ratio. The mean length of sexual maturity (Lm50) was 18.0 cm in females and 20.1 cm in males, reflecting that females mature at smaller sizes than males. The monthly variations of the gonadosomatic index (GSI) and the stages of sexual maturity show two reproductive peaks during the study, in October 2017 and April 2018, coinciding with the rainy and dry seasons in the region respectively. The condition factor (CF) showed significant differences between months, but not between sexes, with an average of 1.87 in females and 1.84 in males. The average absolute fecundity was 921 ± 604.6 eggs per fish, with a relative fecundity of 8.36 ± 3.09 eggs per gram of fish. Differences in oocyte size in mature females confirm that the species can spawn repeatedly over a period, which is considered an important factor for the establishment of tilapia in non-native environments.

"Sexual Development": Timing Puberty in German Enlightenment Medicine (1778-99).

From the mid-eighteenth century onward, French vitalists started to re-theorize the bodily clock of maturation. Archaic notions of precocity as an ill omen and ancient constructions of sexual timing as ethnic markers now acquired an increasingly physiological profile. Regulatory conceptions of sexual and psychosexual "development" widely animated German literature in the closing decades of the century. Here is evidence of new interdisciplinary problematizations of pubescence (Mannbarkeit) as the coordination in time of the mental apparatus (Seele, Character) and the sex drive (Geschlechtstrieb). New developmental-physiological frames for sexual maturity and psychosexuality readily extended to the fate of Nationalcharacter, sponsoring various roundtables concerning etiological questions.

À partir du milieu du XVIIIe siècle, les vitalistes français ont commencé à théoriser à nouveau l'horloge corporelle de la maturation. Les représentations archaïques de la précocité, considérée comme un mauvais présage, et les anciennes constructions du calendrier sexuel, perçues sous l'angle des marqueurs ethniques, ont acquis un profil de plus en plus physiologique. De fait, les conceptions réglementaires du « développement ¼ sexuel et psychosexuel ont largement animé la littérature allemande au cours des dernières décennies du XVIIIe siècle. On y trouve des preuves de nouvelles problématisations interdisciplinaires de la puberté (Mannbarkeit) en tant que coordination dans le temps de l'appareil mental (Seele, Character) et de la libido (Geschlechtstrieb). Les nouveaux cadres développementaux et physiologiques de la maturité sexuelle et de la psychosexualité ont également influencé le Nationalcharacter, qui a parrainé diverses tables rondes sur les questions étiologiques.

Early-Life Resource Scarcity in Mice Does Not Alter Adult Corticosterone or Preovulatory Luteinizing Hormone Surge Responses to Acute Psychosocial Stress.

Early-life stressors can affect reproductive development and change responses to adult stress. We tested if resource scarcity in the form of limited bedding and nesting (LBN) from postnatal days (PND) 4 to 11 delayed sexual maturation in male and female mice and/or altered the response to an acute, layered, psychosocial stress (ALPS) in adulthood. Contrary to the hypotheses, age and mass at puberty were unaffected by the present application of LBN. Under basal conditions and after ALPS, corticosterone concentrations in males, diestrous females, and proestrous females reared in standard (STD) or LBN environments were similar. ALPS disrupts the luteinizing hormone (LH) surge in most mice when applied on the morning of proestrus; this effect was not changed by resource scarcity. In this study, the paucity of effects in the offspring may relate to a milder response of CBA dams to the paradigm. While LBN dams exited the nest more often and their offspring were smaller than STD-reared offspring on PND11, dam corticosterone concentrations were similar on PND11. To test if ALPS disrupts the LH surge by blunting the increase in excitatory GABAergic input to gonadotropin-releasing hormone (GnRH) neurons on the afternoon of proestrus, we conducted whole-cell voltage-clamp recordings. The frequency of GABAergic postsynaptic currents in GnRH neurons was not altered by LBN, ALPS, or their interaction. It remains possible that ALPS acts at afferents of GnRH neurons, changes response of GnRH neurons to input, and/or alters pituitary responsiveness to GnRH and that a more pronounced resource scarcity would affect the parameters studied.

Acute Stress Affects the Relaxin/Insulin-Like Family Peptide Receptor 3 mRNA Expression in Brain of Pubertal Male Wistar Rats.

The current literature suggests that relaxin-3/relaxin/insulin-like family peptide receptor 3 (RLN-3/RXFP-3) system is involved in the pathophysiology of affective disorders because the results of anatomical and pharmacological studies have shown that the RLN-3 signaling pathway plays a role in modulating the stress response, anxiety, arousal, depression-like behavior, and neuroendocrine homeostasis. The risk of developing mental illnesses in adulthood is increased by exposure to stress in early periods of life. The available data indicate that puberty is especially characterized by the development of the neural system and emotionality and is a "stress-sensitive" period. The presented study assessed the short-term changes in the expression of RLN-3 and RXFP-3 mRNA in the stress-dependent brain regions in male pubertal Wistar rats that had been subjected to acute stress. Three stressors were applied from 42 to 44 postnatal days (first day: a single forced swim; second day: stress on an elevated platform that was repeated three times; third day: restraint stress three times). Anxiety (open field, elevated plus maze test) and anhedonic-like behavior (sucrose preference test) were estimated during these tests. The corticosterone (CORT) levels and blood morphology were estimated. We found that the RXFP-3 mRNA expression decreased in the brainstem, whereas it increased in the hypothalamus 72 h after acute stress. These molecular changes were accompanied by the increased levels of CORT and anxiety-like behavior detected in the open field test that had been conducted earlier, that is, 24 h after the stress procedure. These findings shed new light on the neurochemical changes that are involved in the compensatory response to adverse events in pubertal male rats and support other data that suggest a regulatory interplay between the RLN-3 pathway and the hypothalamus-pituitary-adrenal axis activity in the mechanisms of anxiety-like behavior.

Reproductive biology of Donax striatus (Linnaeus, 1758) (Mollusca: Bivalvia) on Gado Bravo Beach, municipality of Tibau do Norte, state of Rio Grande do Norte, Brazil.

Aspects of the reproductive biology of Donax striatus were studied from individuals collected from Gado Bravo Beach in the municipality of Tibau do Norte, state of Rio Grande do Norte, Brazil. Donax striatus is a dioic species without external (on the shell) or internal (gonads) macroscopic dimorphism. Thus, a microscopic examination of the reproductive cells is necessary. For the characterization of the gonadal development stages and determination of the size at first sexual maturity (L50), 30 specimens were selected monthly between February 2021 and January 2022 and submitted to histological processing. The condition index (CI) of each individual was estimated and monthly variations were statistically assessed. The size at first maturity (L50) was estimated to be 14.2 mm in shell length. To foster conservation of the species, catches of individuals larger than 14.2 mm is recommended. The lowest condition indices were found in the dry season, with a greater occurrence of organisms in the elimination stage and exhibiting gonad tissue reorganization. Higher indices were found in the rainy season, with the presence of mature individuals. The continuous nature of gametogenesis in Donax stritatus reflects the influence of rainfall in the region. Males and females have peak gamete elimination with pauses during the year, but with the presence of maturing and eliminating individuals throughout the year. As shellfish gathering targeting Donax striatus is excessive on Gado Bravo Beach in the state of Rio Grande do Norte, it is hoped that the results of the present study can contribute to the establishment of management measures for the activity and conservation strategies for the species.

Exploring the effects of methodological choices on the estimation and biological interpretation of life history parameters for harbour porpoises in Norway and beyond.

This study investigates effects of subtle methodological choices on the estimation and biological interpretation of age, growth and reproductive parameters for harbour porpoises. The core analyses are based on a focal Norwegian data set built on samples from 134 harbour porpoises caught incidentally in gillnet fisheries along the Norwegian coast during autumn 2016 and spring 2017. Two contrasting practices for interpretation of seasonal and ontogenetic characteristics of tooth growth layer formation resulted in significant age differences among spring samples of young porpoises and for older animals across seasons. In turn, these differences affected estimates of age at maturity and asymptotic lengths, respectively. We also found significant differences in male age at maturity between two well-documented maturity criteria and between mathematical estimators of age at maturity for both sexes. Two different criteria for corpus albicans classification furthermore resulted in different patterns of ovarian corpora accumulation, which may affect some estimates of fecundity rates and contaminant loads. Both corpora accumulation patterns were also found in reanalysed data from German and Greenlandic porpoises. Based on tabulated overviews of methodological choices made in previous harbour porpoise studies, we argue that several of the issues mentioned above have wider relevance and may affect the validity of meta-analyses as a tool for estimating harbour porpoise sensitivity to extrinsic pressures. Differences in cause of death (COD) composition between data sets can have a similar effect. We demonstrate this in a meta-analysis of published harbour porpoise pregnancy rates, showing significantly higher values for trauma-killed samples compared to samples comprising mixed COD categories. COD also affected the estimated impacts of three previously analysed extrinsic predictors as well as an added predictor for vessel noise levels. We discuss the potential contributions of methodological, biological and anthropogenic factors in shaping observed regional differences in estimates of harbour porpoise life history parameters.

Pubertal stress in male rats: Effects on juvenile play behavior and adult sexual partner preference.

Puberty is a period of brain organization impacting the expression of social and sexual behaviors. Here, we assessed the effects of an acute pubertal stressor (immune challenge) on the expression of juvenile play (short-term) and sexual partner preference (long-term) in male rats. Juvenile play was assessed over ten trials at postnatal days (PND) (31-40) with age- and sex-matched conspecifics, and at PND35 males received a single injection of lipopolysaccharide (LPS, 1.5 mg/kg i.p.) or saline. Then, sexual partner preference was assessed at PND 60, 64, and 68, in a three-compartment chamber with a sexually receptive female and a male as potential partners simultaneously. The results confirmed that a single injection of LPS during puberty induced sickness signs indicative of an immune challenge. However, juvenile play was not affected by LPS treatment during the following days (PND36-40), nor was sexual behavior and partner preference for females in adulthood. These findings highlight that, while other studies have shown that LPS-induced immunological stress during puberty affects behavior and neuroendocrine responses, it does not affect juvenile play and sexual behavior in male rats. This suggests a remarkable resilience of these behavioral systems for adaptation to stressful experiences mediated by immune challenges during critical periods of development. These behaviors, however, might be affected by other types of stress.

Changes in the Bile Acid Pool and Timing of Female Puberty: Potential Novel Role of Hypothalamic TGR5.

CONTEXT: The regulation of pubertal timing and reproductive axis maturation is influenced by a myriad of physiologic and environmental inputs yet remains incompletely understood. OBJECTIVE: To contrast differences in bile acid isoform profiles across defined stages of reproductive maturity in humans and a rat model of puberty and to characterize the role of bile acid signaling via hypothalamic expression of bile acid receptor populations in the rodent model. METHODS: Secondary analysis and pilot studies of clinical cohorts, rodent models, ex vivo analyses of rodent hypothalamic tissues. Bile acid concentrations is the main outcome measure. RESULTS: Lower circulatory conjugated:deconjugated bile acid concentrations and higher total secondary bile acids were observed in postmenarcheal vs pre-/early pubertal adolescents, with similar shifts observed in infantile (postnatal day [PN]14) vs early juvenile (PN21) rats alongside increased tgr5 receptor mRNA expression within the mediobasal hypothalamus of female rats. 16S rRNA gene sequencing of the rodent gut microbiome across postnatal life revealed changes in the gut microbial composition predicted to have bile salt hydrolase activity, which was observed in parallel with the increased deconjugated and increased concentrations of secondary bile acids. We show that TGR5-stimulated GnRH release from hypothalamic explants is mediated through kisspeptin receptors and that early overexpression of human-TGR5 within the arcuate nucleus accelerates pubertal onset in female rats. CONCLUSION: Bile acid isoform shifts along stages of reproductive maturation are conserved across rodents and humans, with preclinical models providing mechanistic insight for the neuroendocrine-hepatic-gut microbiome axis as a potential moderator of pubertal timing in females.

The effect of probiotic supplementation on sleep, depression-like behaviour, and central glucose and lactate metabolism in male and female pubertal mice exposed to chronic sleep disruption.

The prevalence of depression significantly increases during puberty and adolescence. Puberty is the period during which sexual maturity is attained, while adolescence persists beyond puberty and includes physiological, social, emotional, and cognitive maturation. A stressor that has been shown previously to induce depression is chronic sleep disruption. Probiotics can prevent stress-induced depression. However, it was unclear whether probiotics could prevent depression following chronic sleep disruption and what mechanism may be involved. Therefore, we investigated whether pubertal probiotic treatment could prevent depression-like behavior in mice following chronic sleep disruption. We also examined whether probiotic treatment could improve sleep quality, and increase serotonin, tryptophan, glucose, and L-lactate concentrations in chronically sleep-disrupted mice. We hypothesized that probiotic treatment would prevent depression-like behavior, improve sleep quality, and increase serotonin, tryptophan, glucose, and L-lactate concentrations in sleep-disrupted mice. Male and female mice (N=120) received cannula and electroencephalogram (EEG) electrode implants at postnatal day (PND) 26. Mice received Lacidofil® or Cerebiome® probiotics (PND 33-51) and were sleep-disrupted for the first 4 hours of the light phase (sleep period) (PND 40-51). Hippocampal L-lactate and glucose concentrations and sleep were measured over a 24-h period (PND 48-49). Depression-like behaviour was evaluated using tail suspension (PND 49) and forced swim tests (PND 50). Chronic sleep disruption increased depression-like behaviour and NREM duration in the dark phase, and reduced all metabolites and neuromodulating biomolecules measured within the brain. However, mice treated with probiotics did not display depression-like behaviour or decreased hippocampal L-lactate following chronic sleep disruption. Cerebiome prevented decreases to prefrontal serotonin and hippocampal glucose concentrations, while Lacidofil increased NREM duration in the latter half of the light phase. The current study not only replicates previous findings linking chronic sleep disruption to depression, but also demonstrates that pubertal probiotic treatment can mitigate the effects of chronic sleep disruption on depression-like behaviour and on the neural mechanisms underlying depression in a strain-dependent manner.

GHSR signalling in perinatal phases is involved in liver metabolism at puberty.

Ghrelin has effects that range from the maturation of the central nervous system to the regulation of energy balance. The production of ghrelin increases significantly during the first weeks of life. Studies have addressed the metabolic effects of liver-expressed antimicrobial peptide 2 (LEAP2) in inhibiting the effects evoked by ghrelin, mainly in glucose homeostasis, insulin resistance, and lipid metabolism. Despite the known roles of ghrelin in the postnatal development, little is known about the long-term metabolic influences of modulation with the endogenous expressed growth hormone secretagogue receptor (GHSR) inverse agonist LEAP2. This study aimed to evaluate the contribution of GHSR signalling during perinatal phases, to neurodevelopment and energy metabolism in young animals, under inverse antagonism by LEAP2[1-14]. For this, two experimental models were used: (i) LEAP2[1-14] injections in female rats during the pregnancy. (ii) Postnatal modulation of GHSR with LEAP2[1-14] or MK677. Perinatal GHSR modulation by LEAP2[1-14] impacts glucose homeostasis in a sex and phase-dependent manner, despite no effects on body weight gain or food intake. Interestingly, liver PEPCK expression was remarkably impacted by LEAP2 injections. The observed results suggests that perinatal LEAP2 exposure can modulate liver metabolism and systemic glucose homeostasis. In addition, these results, although not expressive, may just be the beginning of the metabolic imbalance that will occur in adulthood.

Sirenian (manatees and dugongs) reproductive endocrinology.

Reproductive hormones are essential to mating systems, behavior, fertility, gestation, parturition, and lactation in mammals and understanding the role of hormones in these processes is essential for species conservation. Sirenia is a unique order of marine mammals that include manatees, dugongs, and the extinct Steller's sea cow. Extant Sirenian species are all listed as vulnerable due to habitat loss, cold stress, boat strike trauma, harmful algal bloom toxicity, entanglements, and illegal hunting. Therefore, successful reproduction is essential to maintaining and increasing Sirenian populations. Understanding Sirenian reproductive behavior, endocrinology, and mating strategies will aid conservation and management efforts to protect and provide the proper conditions for successful reproduction. The objectives of this review were to synthesize the current knowledge regarding reproductive cycles and endocrinology of Sirenians and identify knowledge gaps for future investigation. The current literature on Sirenian reproductive physiology reports reproductive seasonality, sexual maturation, estrous cyclicity and acyclicity, pregnancy, and sex differences. However, there remain significant knowledge gaps on the cyclicity and pulsatile release of gonadotropins, maturation in females, and characterization of pregnancy hormone profiles throughout gestation. To date, there is no explanation for confirmed pattern for ovarian acyclicity, nor understanding of the function of the numerous accessory corpus luteum described in manatees. Research including a greater number of longitudinal and postmortem studies on a wider variety of wild manatee populations are important first steps. Taken together, understanding the reproductive endocrinology of these vulnerable and threatened species is critical for policy and management decisions to better inform protection initiatives.

Evaluation of hormones as candidate early biomarkers of Holstein bull performance around the first semen collection at artificial insemination centres.

Artificial insemination (AI) centres select bulls as calves according to their genetic breeding values and raise them until the first semen collection; yet, a high dropout rate of reared bulls is a problem for AI centres. Potential hormonal indicators of bull sexual maturation (cortisol, dehydroepiandrosterone (DHEA), testosterone, oestradiol, insulin-like growth factor 1 (IGF-1)) were observed and evaluated in relation to the performance parameters to perhaps identify candidate biomarkers allowing an early selection of bulls as suitable sires. Blood samples from 102 German Holstein calves at 4 ± 1, 8 ± 1 and 12 ± 2 months of age from six AI centres were analysed using validated immunoassays for cortisol, DHEA, testosterone, oestradiol and IGF-1. Semen analyses included native and thawed diluted semen. Bulls were classified at the first semen collection into groups with good versus poor performance (GP vs. LP). After 2 years, the subsequent differentiation was done in high (HPP), medium (MPP) and low performance persistency (LPP). Age at first semen collection was an important factor for sperm quality. Cortisol concentrations decreased with age, but the cortisol/DHEA ratio decreased with age only in GP bulls (p < .05). Oestradiol and testosterone concentrations both correlated with libido behaviour (p < .05). Testosterone and IGF-1 concentrations were higher at the time of first semen collection in GP bulls and increased with age (p < .05). In conclusion, testosterone and IGF-1 concentrations at first semen collection are associated with performance at first semen collection and future performance persistency, and might be useful early biomarkers for consistent sperm producing bulls on AI centres.

Secular trends and sociodemographic, biological, and behavioural factors associated with handgrip strength in adolescents in southern Brazil: An allometric approach.

The purpose of this study was to analyse secular trend in handgrip strength (HGS) in adolescents using an allometric approach and identify the factors associated. The sample comprised 657 and 1004 adolescents (14 to 19 years) in 2007 and 2017/2018, respectively, of public schools in Florianópolis, Brazil. The dependent variable was HGS normalised to body mass and height. Covariance analysis was used to examine secular trends in HGS, and multiple linear regression was used to identify associated factors. The independent variables were sociodemographic, biological, and behavioural factors. Comparison of HGS between surveys indicated a negative secular trend in both sexes (p < 0.001). In boys, there was a positive association of HGS with age and FFM in both surveys. In 2017/18, there was a positive association with sexual maturation and a negative association with sitting time and fat percentage. In girls, FFM was positively associated with HGS in both surveys. In 2007, there were positive associations of HGS with age and vigorous physical activity, whereas, in 2017/18, negative associations were observed with economic level and sitting time. The findings of the present study show a decline in adolescent HGS. And behavioural changes appear to be contributing to declines in HGS.

Transcriptomic Analysis of Pubertal and Adult Virgin Mouse Mammary Epithelial and Stromal Cell Populations.

Conflicting data exist as to how mammary epithelial cell proliferation changes during the reproductive cycle. To study the effect of endogenous hormone fluctuations on gene expression in the mouse mammary gland, we performed bulk RNAseq analyses of epithelial and stromal cell populations that were isolated either during puberty or at different stages of the adult virgin estrous cycle. Our data confirm prior findings that proliferative changes do not occur in every mouse in every cycle. We also show that during the estrous cycle the main gene expression changes occur in adipocytes and fibroblasts. Finally, we present a comprehensive overview of the Wnt gene expression landscape in different mammary gland cell types in pubertal and adult mice. This work contributes to understanding the effects of physiological hormone fluctuations and locally produced signaling molecules on gene expression changes in the mammary gland during the reproductive cycle and should be a useful resource for future studies investigating gene expression patterns in different cell types across different developmental timepoints.

Developmental stage dependent effects of posterior and germline regeneration on sexual maturation in Platynereis dumerilii.

Regeneration, regrowing lost and injured body parts, is an ability that generally declines with age or developmental transitions (i.e. metamorphosis, sexual maturation). Regeneration is also an energetically costly process, and trade-offs occur between regeneration and other costly processes such as growth, or sexual reproduction. Here we investigate the interplay of regeneration, reproduction, and developmental stage in the segmented worm Platynereis dumerilii. P. dumerilii can regenerate its whole posterior body axis, along with its reproductive cells, thereby having to carry out the two costly processes (somatic and germ cell regeneration) after injury. We specifically examine how developmental stage affects the success of germ cell regeneration and sexual maturation in developmentally young versus developmentally old organisms. We hypothesized that developmentally younger individuals (i.e. with gametes in early mitotic stages) will have higher regeneration success than the individuals at developmentally older stages (i.e. with gametes undergoing meiosis and maturation). Surprisingly, older amputated worms grew faster and matured earlier than younger amputees. To analyze germ cell regeneration during and after posterior regeneration, we used Hybridization Chain Reaction for the germline marker vasa. We found that regenerated worms start repopulating new segments with germ cell clusters as early as 14 days post amputation. In addition, vasa expression is observed in a wide region of newly-regenerated segments, which appears different from expression patterns during normal growth or regeneration in worms before gonial cluster expansion.

Pubertal Timing Across Asian American, Native Hawaiian, and Pacific Islander Subgroups.

Importance: Earlier puberty is associated with adverse health outcomes, such as mental health issues in adolescence and cardiometabolic diseases in adulthood. Despite rapid growth of the Asian American, Native Hawaiian, and Pacific Islander populations in the US, limited research exists on their pubertal timing, potentially masking health disparities. Objective: To examine pubertal timing among Asian American, Native Hawaiian, and Pacific Islander children and adolescents by disaggregating ethnic subgroups. Design, Setting, and Participants: This retrospective cohort study included Asian American, Native Hawaiian, and Pacific Islander youths aged 5 to 18 years assessed for pubertal development at Kaiser Permanente Northern California, a large, integrated health care delivery system. Follow-up occurred from March 2005, through December 31, 2019. Data were analyzed in October 2023. Exposure: Race and ethnicity, categorized into 11 ethnic subgroups: Asian Indian, Chinese, Filipino, Japanese, Korean, Native Hawaiian and Pacific Islander, Other South Asian, Other Southeast Asian, Vietnamese, multiethnic, and multiracial. Main Outcomes and Measures: Pubertal timing was determined using physician-assessed sexual maturity ratings (SMRs). Outcomes included the median age at transition from SMR 1 (prepubertal) to SMR 2 or higher (pubertal) for onset of genital development (gonadarche) in boys, breast development (thelarche) in girls, and pubic hair development (pubarche) in both boys and girls. Results: In this cohort of 107 325 Asian American, Native Hawaiian, and Pacific Islander children and adolescents (54.61% boys; 12.96% Asian Indian, 22.24% Chinese, 26.46% Filipino, 1.80% Japanese, 1.66% Korean, 1.96% Native Hawaiian and Pacific Islander, 0.86% Other South Asian, 3.26% Other Southeast Asian, 5.99% Vietnamese, 0.74% multiethnic, and 22.05% multiracial), the overall median ages for girls' pubarche and thelarche were 10.98 years (95% CI, 10.96-11.01 years) and 10.13 years (95% CI, 10.11-10.15 years), respectively. For boys' pubarche and gonadarche, median ages were 12.08 years (95% CI, 12.06-12.10 years) and 11.54 years (95% CI, 11.52-11.56 years), respectively. Differences between subgroups with earliest and latest median age at onset were 14 months for girls' pubarche, 8 months for thelarche, 8 months for boys' pubarche, and 4 months for gonadarche. In general, Asian Indian, Native Hawaiian and Pacific Islander, and Other South Asian subgroups had the earliest ages at onset across pubertal markers, while East Asian youths exhibited the latest onset. Restricting to those with healthy body mass index did not substantially change the findings. Conclusions and Relevance: In this cohort study of Asian American, Native Hawaiian, and Pacific Islander children and adolescents, pubertal timing varied considerably across ethnic subgroups. Further investigation is warranted to assess whether these differences contribute to observed health disparities in adulthood, such as type 2 diabetes and cardiovascular diseases.

Decoding the effect of photoperiodic cues in transducing kisspeptin-melatonin circuit during the pubertal onset in common carp.

This study unravels the intricate interplay between photoperiod, melatonin, and kisspeptin to orchestrate the pubertal onset of Common carp. Female fingerlings exposed to long days (LD) exhibited a hormonal crescendo, with upregulated hypothalamic-pituitary-ovarian (HPO) axis genes (kiss1, kiss1r, kiss2, gnrh2, gnrh3) and their downstream targets (lhr, fshr, ar1, esr1). However, the expression of the melatonin receptor (mtnr1a) diminished in LD, suggesting a potential inhibitory role. This hormonal symphony was further amplified by increased activity of key transcriptional regulators (gata1, gata2, cdx1, sp1, n-myc, hoxc8, plc, tac3, tacr3) and decreased expression of delayed puberty genes (mkrn1, dlk1). In contrast, short days (SD) muted this hormonal chorus, with decreased gnrh gene and regulator expression, elevated mtnr1a, and suppressed gonadal development. In in-vitro, estradiol mimicked the LD effect, boosting gnrh and regulator genes while dampening mtnr1a and melatonin-responsive genes. Conversely, melatonin acted as a conductor, downregulating gnrh and regulator genes and amplifying mtnr1a. Our findings illuminate the crucial roles of melatonin and kisspeptin as opposing forces in regulating pubertal timing. LD-induced melatonin suppression allows the kisspeptin symphony to flourish, triggering GnRH release and, ultimately, gonadal maturation. This delicate dance between photoperiod, melatonin, and kisspeptin orchestrates common carp's transition from juvenile to reproductive life.

New liquid chromatography tandem mass spectrometry reference data for estradiol show mini-puberty in both sexes and typical pre-pubertal and pubertal patterns.

CONTEXT: Reliable estradiol (E2) reference intervals (RIs) are crucial in pediatric endocrinology. OBJECTIVES: This study aims to develop a sensitive ultra-performance liquid chromatographic tandem mass spectrometry (UPLC-MS/MS) method for E2 in serum, to establish graphically represented RI percentiles and annual RIs for both sexes, and to perform a systematic literature comparison. METHODS: First, a UPLC-MS/MS method for E2 was developed. Second, graphically represented RI percentiles and annual RIs covering 0-18 years were computed (cohort of healthy children [1181 girls and 543 boys]). Subsequently, RIs were compared with published data by systematic searches. RESULTS: Lower limit of quantification was 11 pmol/L, indicating high sensitivity. Estradiol first peaked during mini-puberty in both sexes (girls up to 192 pmol/L; boys up to 225 pmol/L). As could be expected, girls showed higher pubertal E2 (up to 638 pmol/L). However, boys' RIs (up to 259 pmol/L) overlapped considerably. We found 4 studies in the literature that also used LC-MS/MS to determine E2 and published RIs for the complete pediatric age range. Reference intervals varied considerably. Pre-pubertal and pubertal phases were present in all studies. Higher E2 during the time of mini-puberty in both sexes was documented in 3 studies including ours. CONCLUSIONS: Variability of RIs for E2 between studies illustrates the importance of laboratory-specific RIs despite using a LC-MS/MS reference method. In boys, the striking E2 peak during mini-puberty as well as high pubertal E2 without phenotypic estrogenization in regular male puberty indicates that the role of E2 in children and, especially in boys, requires better functional understanding.

Age-related changes in densitometry and histomorphometry of long bone during the pubertal growth spurt in male rats.

Because experimental studies to determine the developmental toxicity of exposure to various substances in children are impossible, many studies use immature male rats. This study aimed to provide normative data for longitudinal bone growth with age during the puberty in male rats. In order to evaluate long bone growth and mineralization we examined bone size and bone density by dual-energy X-ray absorptiometry, analyzed histomorphometry of the growth plate, and serum hormone levels relevant to bone growth from postnatal day (PD)20 to PD60. The length and weight of long bones increased strongly by PD40, and no further increase was observed after PD50. On the other hand, tibial growth plate height decreased sharply after PD50 along with a reduction in the number of cells and columns, which was probably responsible for the absence of further lengthening of long bones. Parameters related to bone formation such as bone area ratio, and the thickness and number of trabeculae, also increased significantly between PD40 and PD50. Furthermore, serum levels of IGF-1 peaked at PD30 and testosterone increased rapidly on and after PD40, when IGF-1 levels were going down. These changes may participate in the parallel increase in mineral acquisition, as well as lengthening of long bones. Our findings provide comprehensive data for changes in bone density, histomorphometry of long bones, and hormone levels relevant to bone growth during the growth spurt. This will be useful for planning animal toxicological studies, particularly for deciding on the appropriate age of animals to use in given experiments.

Integrative proteomic and transcriptomic analysis in the female goat ovary to explore the onset of puberty.

Puberty is considered a prerequisite for affecting reproductive performance and productivity. Little was known about molecular changes in pubertal goat ovaries. Therefore, we measured and performed a correlation analysis of the mRNA and proteins changes in the pre-pubertal and pubertal goat ovaries. The results showed that only six differentially expressed genes and differentially abundant proteins out of 18,139 genes and 7550 proteins quantified had significant correlations. CNTN2 and THBS1, discovered in the mRNA-mRNA interaction network, probably participated in pubertal and reproductive regulation by influencing GnRH receptor signals, follicular development, and ovulation. The predicted core transcription factors may either promote or inhibit the expression of reproductive genes and act synergistically to maintain normal reproductive function in animals. The interaction between PKM and TIMP3 with other proteins may impact animal puberty through energy metabolism and ovarian hormone secretion. Pathway enrichment analyses revealed that the co-associated key pathways between ovarian genes and proteins at puberty included calcium signalling pathway and olfactory transduction. These pathways were associated with gonadotropin-releasing hormone synthesis and secretion, signal transmission, and cell proliferation. In summary, these results enriched the potential molecules and signalling pathways that affect puberty and provided new insights for regulating and promoting the onset of puberty. SIGNIFICANCE: This study conducted the first transcriptomic and proteomic correlation analysis of pre-pubertal and pubertal goat ovaries and identified six significantly correlated molecules at both the gene and protein levels. Meanwhile, we were drawn to several molecules and signalling pathways that may play a regulatory role in the onset of puberty and reproduction by influencing reproductive-related gene expression, GnRH receptor signals, energy metabolism, ovarian hormone secretion, follicular development, and ovulation. This information contributed to identify potential biomarkers in pubertal goat ovaries, which was vital for predicting the onset of puberty and improving livestock performance.