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Nature Reviews. Endocrinology Jan 2018Natural fluctuations in physiological conditions require adaptive responses involving rapid and reversible structural and functional changes in the hypothalamic... (Review)
Review
Natural fluctuations in physiological conditions require adaptive responses involving rapid and reversible structural and functional changes in the hypothalamic neuroendocrine circuits that control homeostasis. Here, we discuss the data that implicate hypothalamic glia in the control of hypothalamic neuroendocrine circuits, specifically neuron-glia interactions in the regulation of neurosecretion as well as neuronal excitability. Mechanistically, the morphological plasticity displayed by distal processes of astrocytes, pituicytes and tanycytes modifies the geometry and diffusion properties of the extracellular space. These changes alter the relationship between glial cells of the hypothalamus and adjacent neuronal elements, especially at specialized intersections such as synapses and neurohaemal junctions. The structural alterations in turn lead to functional plasticity that alters the release and spread of neurotransmitters, neuromodulators and gliotransmitters, as well as the activity of discrete glial signalling pathways that mediate feedback by peripheral signals to the hypothalamus. An understanding of the contributions of these and other non-neuronal cell types to hypothalamic neuroendocrine function is thus critical both to understand physiological processes such as puberty, the maintenance of bodily homeostasis and ageing and to develop novel therapeutic strategies for dysfunctions of these processes, such as infertility and metabolic disorders.
Topics: Animals; Cell Communication; Humans; Hypothalamus; Neuroglia; Neurons; Neurosecretory Systems; Sexual Maturation
PubMed: 29076504
DOI: 10.1038/nrendo.2017.124 -
Journal of Adolescence Feb 2019Puberty is a physiological event involving the attainment of reproductive capability and complete development of sexual and physical organs. Changing from childhood to... (Review)
Review
Puberty is a physiological event involving the attainment of reproductive capability and complete development of sexual and physical organs. Changing from childhood to adulthood is a complex process and is tightly controlled by interconnection pathways at the level of the hypothalamus which can be influenced by environmental, psychosocial, and endocrine factors. Although various mechanisms underlying the onset of normal puberty have been investigated in humans and animals, the exact molecular mechanisms thereof remain unclear. The aim of this review is to summarize the current state of knowledge and provide a synoptic overview about the physiology of puberty in adolescent boys and girls, and describe pathological disorders affecting its onset.
Topics: Adolescent; Disorders of Sex Development; Female; Humans; Male; Puberty; Sex Characteristics; Sexual Maturation
PubMed: 30639665
DOI: 10.1016/j.adolescence.2018.12.007 -
Birth Defects Research Feb 2018The postnatal development of the female reproductive system in laboratory animals and humans is reviewed. To enable a meaningful species comparison of the developing... (Comparative Study)
Comparative Study Review
The postnatal development of the female reproductive system in laboratory animals and humans is reviewed. To enable a meaningful species comparison of the developing female reproductive system, common definitions of developmental processes were established with a focus made on aspects that are similar across species. A species comparison of the key endocrine, morphologic, and functional (onset of ovarian cycles and ability to reproduce) features of postnatal development of the female reproductive system is provided for human, nonhuman primate, dog, rat, and also mouse, minipig, and rabbit where possible. Species differences in the timing and control of female sexual maturation are highlighted. Additionally, a species comparison of the type and timing of female reproductive ovarian cycles was compiled. Human development provided the frame of reference, and then other common laboratory species were compared. The comparison has inherent challenges because the processes involved and sequence of events can differ greatly across species. Broad strokes were taken to assign a particular average age to an event and are to be used with caution. Methods of evaluation of postnatal female reproductive development in laboratory animals are discussed. Lastly, control rodent data from one of the author's laboratory on vaginal opening, first estrus, estrous cyclicity, and the histopathology involved with the developing female rat and mouse are presented. The information provided in this review is intended to be a resource for the design and interpretation of juvenile animal toxicity testing and ultimately, the relevance of the data to characterize potential risks for women and girls. Birth Defects Research 110:163-189, 2018. © 2017 Wiley Periodicals, Inc.
Topics: Animals; Female; Genitalia, Female; Humans; Sexual Maturation; Species Specificity
PubMed: 29243395
DOI: 10.1002/bdr2.1132 -
Nature Reviews. Endocrinology Aug 2016The gonadotropin-releasing hormone (GnRH) neuronal network generates pulse and surge modes of gonadotropin secretion critical for puberty and fertility. The arcuate... (Review)
Review
The gonadotropin-releasing hormone (GnRH) neuronal network generates pulse and surge modes of gonadotropin secretion critical for puberty and fertility. The arcuate nucleus kisspeptin neurons that innervate the projections of GnRH neurons in and around their neurosecretory zone are key components of the pulse generator in all mammals. By contrast, kisspeptin neurons located in the preoptic area project to GnRH neuron cell bodies and proximal dendrites and are involved in surge generation in female rodents (and possibly other species). The hypothalamic-pituitary-gonadal axis develops embryonically but, apart from short periods of activation immediately after birth, remains suppressed through a combination of gonadal and non-gonadal mechanisms. At puberty onset, the pulse generator reactivates, probably owing to progressive stimulatory influences on GnRH neurons from glial and neurotransmitter signalling, and the re-emergence of stimulatory arcuate kisspeptin input. In females, the development of pulsatile gonadotropin secretion enables final maturation of the surge generator that ultimately triggers the first ovulation. Representation of the GnRH neuronal network as a series of interlocking functional modules could help conceptualization of its functioning in different species. Insights into pulse and surge generation are expected to aid development of therapeutic strategies ameliorating pubertal disorders and infertility in the clinic.
Topics: Animals; Brain; Female; Fertility; Gonadotropin-Releasing Hormone; Humans; Neurons; Puberty; Sexual Maturation
PubMed: 27199290
DOI: 10.1038/nrendo.2016.70 -
Pediatric Endocrinology Reviews : PER Sep 2017Carbohydrate-restricted diets are known for their impact on weight loss; however, research is still required to determine if low-carbohydrate diets are safe for... (Review)
Review
Carbohydrate-restricted diets are known for their impact on weight loss; however, research is still required to determine if low-carbohydrate diets are safe for adolescents. Carbohydrates directly stimulate an insulin response, and studies have recently shown that insulin and binding to respective insulin receptors (IRs) are critical in Kisspeptin (Kiss1) neuronal development. These neurons directly stimulate gonadotropin-releasing hormone, which activates the pituitary-gonadal axis during puberty. This information suggests that carbohydrate restriction may delay pubertal development in adolescents due to the impact on insulin and Kiss1 transcription. Studies have observed disturbed insulin metabolism in Type I Diabetics leading to delayed puberty, along with overfeeding stimulating early pubertal onset. Additionally, recent clinical trials bred female mice with IR deletions on Kiss1 neurons and observed delayed vaginal opening and estrus. Current animal research suggests low carbohydrate intake may delay pubertal onset, however additional research is required to determine outcome in human subjects.
Topics: Adolescent; Adolescent Development; Adolescent Health; Animals; Caloric Restriction; Dietary Carbohydrates; Female; Humans; Mice; Neurons; Sexual Maturation
PubMed: 28845625
DOI: 10.17458/per.vol15.2017.rd.impactcarbohydraterestriction -
BMC Research Notes Jan 2019To determine the influence of sexual maturation status on adiposity indicators of children and adolescents.
OBJECTIVES
To determine the influence of sexual maturation status on adiposity indicators of children and adolescents.
RESULTS
2412 individuals participated, 1285 (47.4%) males and 1408 (52.6%) females. There was moderate to weak correlation between age and adiposity indicators for both sexes. By analyzing the relationship between age and body fat indexes adjusted for Sexual Maturation Status, several changes were observed, mainly in girls. Precocious maturation was associated with increased adiposity indicators in girls, whereas late maturation was associated with decreased adiposity indicators in both sexes. Precocious maturation was associated with increased adiposity indicators in girls, whereas late maturation was associated with decreased adiposity indicators in both sexes.
Topics: Adiposity; Adolescent; Age Factors; Brazil; Child; Comorbidity; Female; Humans; Male; Pediatric Obesity; Puberty, Delayed; Puberty, Precocious; Sexual Maturation
PubMed: 30683149
DOI: 10.1186/s13104-019-4095-5 -
The Journal of Comparative Neurology Jul 2019Maximal longevity of endotherms has long been considered to increase with decreasing specific metabolic rate, and thus with increasing body mass. Using a dataset of over...
Maximal longevity of endotherms has long been considered to increase with decreasing specific metabolic rate, and thus with increasing body mass. Using a dataset of over 700 species, here I show that maximal longevity, age at sexual maturity, and postmaturity longevity across bird and mammalian species instead correlate primarily, and universally, with the number of cortical brain neurons. Correlations with metabolic rate and body mass are entirely explained by clade-specific relationships between these variables and numbers of cortical neurons across species. Importantly, humans reach sexual maturity and subsequently live just as long as expected for their number of cortical neurons, which eliminates the basis for earlier theories of protracted childhood and prolonged post-menopause longevity as derived human characteristics. Longevity might increase together with numbers of cortical neurons through their impact on three main factors: delay of sexual maturity, which postpones the onset of aging; lengthening of the period of viable physiological integration and adaptation, which increases postmaturity longevity; and improved cognitive capabilities that benefit survival of the self and of longer-lived progeny, and are conducive to prolonged learning and cultural transmission through increased generational overlap. Importantly, the findings indicate that theories of aging and neurodegenerative diseases should take absolute time lived besides relative "age" into consideration.
Topics: Aging; Animals; Cerebral Cortex; Female; Humans; Longevity; Male; Neurons; Sexual Maturation; Species Specificity
PubMed: 30350858
DOI: 10.1002/cne.24564 -
Frontiers in Cellular and Infection... 2023Schistosomes are the only mammalian flatworms that have evolved separate sexes. A key question of schistosome research is the male-dependent sexual maturation of the...
INTRODUCTION
Schistosomes are the only mammalian flatworms that have evolved separate sexes. A key question of schistosome research is the male-dependent sexual maturation of the female since a constant pairing contact with a male is required for the onset of gonad development in the female. Although this phenomenon is long known, only recently a first peptide-based pheromone of males was identified that contributes to the control of female sexual development. Beyond this, our understanding of the molecular principles inducing the substantial developmental changes in a paired female is still rudimentary.
OBJECTIVES
Previous transcriptomic studies have consistently pointed to neuronal genes being differentially expressed and upregulated in paired males. These genes included Smp_135230 and Smp_171580, both annotated as aromatic-L-amino-acid decarboxylases (DOPA decarboxylases). Here, we characterized both genes and investigated their roles in male-female interaction of .
METHODOLOGIES/FINDINGS
Sequence analyses indicated that Smp_135230 represents an L-tyrosine decarboxylase (Sm), whereas Smp_171580 represents a DOPA decarboxylase (Sm). By qRT-PCR, we confirmed the male-specific and pairing-dependent expression of both genes with a significant bias toward paired males. RNA-interference experiments showed a strong influence of each gene on gonad differentiation in paired females, which was enhanced by double knockdown. Accordingly, egg production was significantly reduced. By confocal laser scanning microscopy, a failure of oocyte maturation was found in paired knockdown females. Whole-mount hybridization patterns exhibited the tissue-specific occurrence of both genes in particular cells at the ventral surface of the male, the gynecophoral canal, which represents the physical interface of both genders. These cells probably belong to the predicted neuronal cluster 2 of
CONCLUSION
Our results suggest that Sm and Sm are male-competence factors that are expressed in neuronal cells at the contact zone between the genders as a response of pairing to subsequently control processes of female sexual maturation.
Topics: Female; Male; Animals; Schistosoma mansoni; Sexual Maturation; Schistosomatidae; Cell Differentiation; Gene Expression Profiling; Mammals
PubMed: 37305409
DOI: 10.3389/fcimb.2023.1173557 -
Toxicologic Pathology Jun 2016It is important to know whether the animals used in toxicology studies are sexually mature. As minipigs are being used increasingly in toxicity studies, we reviewed... (Review)
Review
It is important to know whether the animals used in toxicology studies are sexually mature. As minipigs are being used increasingly in toxicity studies, we reviewed published data on the age of sexual maturity in the minipig. Maturity in females was assessed on the basis either of normal cycles of progesterone secretion or of the histological presence of corpora lutea and, in males, was assessed on the histological appearance of the seminiferous tubules and epididymides. In female Göttingen minipigs, the first progesterone peak was at 3.7 to 4.2 or 6.1 to 6.5 months of age. These animals were in the presence of a boar. In female Göttingen minipigs in toxicology studies, which were not in the presence of a boar, at least 1 corpus luteum in the ovaries was present in only 50% of the females by 6.5 months of age, while all were mature by 7.7 months of age. Histological maturity in the male Yucatan minipig is reported to be attained at about 4.4 months old, but in male Göttingen minipigs at about 2 months old, although the definition of maturity may have been different in the 2 studies.
Topics: Animals; Female; Male; Sexual Maturation; Swine; Swine, Miniature
PubMed: 27102651
DOI: 10.1177/0192623316642881 -
Advances in Experimental Medicine and... 2020What is it about sexuality that makes it such a burning matter since the dawn of mankind? Much was lost of humankind heritage because of society's attitude toward sex... (Review)
Review
What is it about sexuality that makes it such a burning matter since the dawn of mankind? Much was lost of humankind heritage because of society's attitude toward sex and gender, but we've made progress. Medical knowledge progressed incredibly and so did social and cultural norms. In these days, on most places on the planet, there is acceptance. Still, gender issues take a center stage, often inflaming the social and political milieu everywhere. So how informed and prepared is the medical community to deal with these issues? Aside from medical treatments, gender dysphoric patients need mental health and social support throughout life. Do we have enough guidelines for treatments that have life-long effects? Do we actually know all of those effects? There are many issues to consider, like fertility preservation, puberty suppression with its adverse effects, and not in the least, the effects of the hormonal therapy on the target tissues.
Topics: Gender Dysphoria; Gender Identity; Hormone Replacement Therapy; Humans; Sexual Behavior; Sexual Maturation; Sexual and Gender Disorders
PubMed: 32406031
DOI: 10.1007/978-3-030-38474-6_7