Kisspeptin signaling in astrocytes modulates the reproductive axis.

Reproduction is safeguarded by multiple, often cooperative regulatory networks. Kisspeptin signaling, via KISS1R, plays a fundamental role in reproductive control, primarily by regulation of hypothalamic GnRH neurons. We disclose herein a pathway for direct kisspeptin actions in astrocytes that contributes to central reproductive modulation. Protein-protein-interaction and ontology analyses of hypothalamic proteomic profiles after kisspeptin stimulation revealed that glial/astrocyte markers are regulated by kisspeptin in mice. This glial-kisspeptin pathway was validated by the demonstrated expression of Kiss1r in mouse astrocytes in vivo and astrocyte cultures from humans, rats and mice, where kisspeptin activated canonical intracellular signaling-pathways. Cellular co-expression of Kiss1r with the astrocyte markers, GFAP and S100-ß, occurred in different brain regions, with higher percentage in Kiss1- and GnRH-enriched areas. Conditional ablation of Kiss1r in GFAP-positive cells, in the G-KiRKO mouse, altered gene expression of key factors in PGE2 synthesis in astrocytes, and perturbed astrocyte-GnRH neuronal appositions, as well as LH responses to kisspeptin and LH pulsatility, as surrogate marker of GnRH secretion. G-KiRKO mice also displayed changes in reproductive responses to metabolic stress induced by high-fat diet, affecting female pubertal onset, estrous cyclicity and LH-secretory profiles. Our data unveil a non-neuronal pathway for kisspeptin actions in astrocytes, which cooperates in fine-tuning the reproductive axis and its responses to metabolic stress.

Enhanced identification of endocrine disruptors through integration of science-based regulatory practices and innovative methodologies: The MERLON Project.

The prevalence of hormone-related health issues caused by exposure to endocrine disrupting chemicals (EDCs) is a significant, and increasing, societal challenge. Declining fertility rates together with rising incidence rates of reproductive disorders and other endocrine-related diseases underscores the urgency in taking more action. Addressing the growing threat of EDCs in our environment demands robust and reliable test methods to assess a broad variety of endpoints relevant for endocrine disruption. EDCs also require effective regulatory frameworks, especially as the current move towards greater reliance on non-animal methods in chemical testing puts to test the current paradigm for EDC identification, which requires that an adverse effect is observed in an intact organism. Although great advances have been made in the field of predictive toxicology, disruption to the endocrine system and subsequent adverse health effects may prove particularly difficult to predict without traditional animal models. The MERLON project seeks to expedite progress by integrating multispecies molecular research, new approach methodologies (NAMs), human clinical epidemiology, and systems biology to furnish mechanistic insights and explore ways forward for NAM-based identification of EDCs. The focus is on sexual development and function, from foetal sex differentiation of the reproductive system through mini-puberty and puberty to sexual maturity. The project aims are geared towards closing existing knowledge gaps in understanding the effects of EDCs on human health to ultimately support effective regulation of EDCs in the European Union and beyond.

The evolutionary conserved miR-137/325 tandem mediates obesity-induced hypogonadism and metabolic comorbidities by repressing hypothalamic kisspeptin.

BACKGROUND: Obesity-induced hypogonadism (OIH) is a prevalent, but often neglected condition in men, which aggravates the metabolic complications of overweight. While hypothalamic suppression of Kiss1-encoded kisspeptin has been suggested to contribute to OIH, the molecular mechanisms for such repression in obesity, and the therapeutic implications thereof, remain unknown. METHODS: A combination of bioinformatic, expression and functional analyses was implemented, assessing the role of the evolutionary-conserved miRNAs, miR-137 and miR-325, in mediating obesity-induced suppression of hypothalamic kisspeptin, as putative mechanism of central hypogonadism and metabolic comorbidities. The implications of such miR-137/325-kisspeptin interplay for therapeutic intervention in obesity were also explored using preclinical OIH models. RESULTS: MiR-137/325 repressed human KISS1 3'-UTR in-vitro and inhibited hypothalamic kisspeptin content in male rats, while miR-137/325 expression was up-regulated, and Kiss1/kisspeptin decreased, in the medio-basal hypothalamus of obese rats. Selective over-expression of miR-137 in Kiss1 neurons reduced Kiss1/ kisspeptin and partially replicated reproductive and metabolic alterations of OIH in lean mice. Conversely, interference of the repressive actions of miR-137/325 selectively on Kiss1 3'-UTR in vivo, using target-site blockers (TSB), enhanced kisspeptin content and reversed central hypogonadism in obese rats, together with improvement of glucose intolerance, insulin resistance and cardiovascular and inflammatory markers, despite persistent exposure to obesogenic diet. Reversal of OIH by TSB miR-137/325 was more effective than chronic kisspeptin or testosterone treatments in obese rats. CONCLUSIONS: Our data disclose that the miR-137/325-Kisspeptin repressive interaction is a major player in the pathogenesis of obesity-induced hypogonadism and a putative druggable target for improved management of this condition and its metabolic comorbidities in men suffering obesity. SIGNIFICANCE STATEMENT: Up to half of the men suffering obesity display also central hypogonadism, an often neglected complication of overweight that can aggravate the clinical course of obesity and its complications. The mechanisms for such obesity-induced hypogonadism remain poorly defined. We show here that the evolutionary conserved miR137/miR325 tandem centrally mediates obesity-induced hypogonadism via repression of the reproductive-stimulatory signal, kisspeptin; this may represent an amenable druggable target for improved management of hypogonadism and other metabolic complications of obesity.

Safety and efficacy of benralizumab in elderly subjects with severe asthma.

INTRODUCTION: The prevalence of asthma in adults >65 years old is approximately 12-14%, and 10% have severe asthma. A higher mortality rate is observed in subjects with asthma >65 years old and especially >80 years old. OBJECTIVE: To analyze the effectiveness and safety of at least three doses of benralizumab in a subgroup of elderly subjects (>65 years old) with uncontrolled severe eosinophilic asthma in real-life conditions. METHODS: This was a retrospective multicenter study (AUTOBENRA study) conducted in 9 hospitals that included 72 patients aged >18 years old with uncontrolled severe asthma based on the Spanish Asthma Guidelines who were treated with at least three doses of benralizumab, self-administered at home since before April 30, 2021. The recruitment period ended on October 1, 2021. Written consent was obtained before the study commencement. In this subanalysis, we compared the results between patients >65 years old and patients <65 years old. RESULTS: A total of 72 subjects with severe asthma were screened, and 54 were included (MD: 57.3 ± 10 years old). There were 12 subjects aged >65 years old [MD: 69.8 ± 4.3 years old (minimum: 65 years old; maximum: 83 years old)]. Subjects >65 years old experienced statistically significant improvement in lung function, ACT and mini-AQLQ with benralizumab. Additionally, 9 patients (75%) experienced no asthma exacerbation (p = 0.0047), half (3/6) were able to stop OCS (p = 0.08), and no adverse effects with benralizumab were reported during the 20 months of follow-up. CONCLUSIONS: In patients aged >65 years old, benralizumab was an effective and safe therapy for severe eosinophilic asthma in our study, with no significant differences from the younger subgroup. This is especially important since they are a group with numerous comorbidities, medications and worse quality of life.

A cannabidiol aminoquinone derivative activates the PP2A/B55α/HIF pathway and shows protective effects in a murine model of traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) is characterized by a primary mechanical injury and a secondary injury associated with neuroinflammation, blood-brain barrier (BBB) disruption and neurodegeneration. We have developed a novel cannabidiol aminoquinone derivative, VCE-004.8, which is a dual PPARγ/CB2 agonist that also activates the hypoxia inducible factor (HIF) pathway. VCE-004.8 shows potent antifibrotic, anti-inflammatory and neuroprotective activities and it is now in Phase II clinical trials for systemic sclerosis and multiple sclerosis. Herein, we investigated the mechanism of action of VCE-004.8 in the HIF pathway and explored its efficacy in a preclinical model of TBI. METHODS: Using a phosphoproteomic approach, we investigated the effects of VCE-004.8 on prolyl hydroxylase domain-containing protein 2 (PHD2) posttranslational modifications. The potential role of PP2A/B55α in HIF activation was analyzed using siRNA for B55α. To evaluate the angiogenic response to the treatment with VCE-004.8 we performed a Matrigel plug in vivo assay. Transendothelial electrical resistance (TEER) as well as vascular cell adhesion molecule 1 (VCAM), and zonula occludens 1 (ZO-1) tight junction protein expression were studied in brain microvascular endothelial cells. The efficacy of VCE-004.8 in vivo was evaluated in a controlled cortical impact (CCI) murine model of TBI. RESULTS: Herein we provide evidence that VCE-004.8 inhibits PHD2 Ser125 phosphorylation and activates HIF through a PP2A/B55α pathway. VCE-004.8 induces angiogenesis in vivo increasing the formation of functional vessel (CD31/α-SMA) and prevents in vitro blood-brain barrier (BBB) disruption ameliorating the loss of ZO-1 expression under proinflammatory conditions. In CCI model VCE-004.8 treatment ameliorates early motor deficits after TBI and attenuates cerebral edema preserving BBB integrity. Histopathological analysis revealed that VCE-004.8 treatment induces neovascularization in pericontusional area and prevented immune cell infiltration to the brain parenchyma. In addition, VCE-004.8 attenuates neuroinflammation and reduces neuronal death and apoptosis in the damaged area. CONCLUSIONS: This study provides new insight about the mechanism of action of VCE-004.8 regulating the PP2A/B55α/PHD2/HIF pathway. Furthermore, we show the potential efficacy for TBI treatment by preventing BBB disruption, enhancing angiogenesis, and ameliorating neuroinflammation and neurodegeneration after brain injury.

Reliability, Satisfaction and Effectiveness of Benralizumab Home Self-Administration in Patients with Severe Eosinophilic Asthma in Real-World Practice: The Auto-Benra Study.

Introduction: The increase in drugs available for severe uncontrolled asthma and the lifestyle of these patients make it necessary to implement self-administration programs of these therapies at home. Benralizumab, a monoclonal antibody targeting IL5R, was authorized in Spain for poorly controlled severe eosinophilic asthma. The possibility of administration at home was approved in March 2020 in Spain. The aim of the Auto-Benra study was to evaluate the usability and satisfaction of the benralizumab prefilled syringe and autoinjector and assessing the effectivity of these devices in uncontrolled severe eosinophilic asthma (SEA) in home-self administration. Methods: This is a retrospective, observational multicenter study uncontrolled SEA patients treated with benralizumab at least with 3 doses self-administered at home before April 30, 2021. Reliability and satisfaction with benralizumab at home were evaluated with subcutaneous administration assessment questionnaire (SQAAQ) and visual analogic scales (VAS). Effectiveness was evaluated in all patients with asthma control test (ACT), Mini Asthma Quality of Life Questionnaire (MiniAQLQ), annual exacerbation rate, oral corticosteroid treatment (OCS) and asthma-related hospitalizations and emergency visits. Results: Fifty-four patients across 9 hospitals in Spain were included. The mean SQAAQ score was 6.89 (±0.16) points. Patients and their caregivers and doctors report excellent satisfaction by VAS, with no differences between benralizumab devices used (prefilled syringe and autoinjector). Severe exacerbation rate decreased by 65% (p = 0.0007) after benralizumab treatment. ACT score improved on average 6.27 ± 5.35 points (p < 0.0001) and the mean MiniAQLQ increased up to 1.58 ± 1.47 points (p < 0.0001). Twenty-four patients were OCS-dependent and at the end of study 14 patients get complete OCS withdrawal. Conclusion: AUTO-BENRA study supports the use of benralizumab at home given the excellent results of satisfaction and usability by patients and their caregivers.

Extrahypothalamic Control of Energy Balance and Its Connection with Reproduction: Roles of the Amygdala.

Body energy and metabolic homeostasis are exquisitely controlled by multiple, often overlapping regulatory mechanisms, which permit the tight adjustment between fuel reserves, internal needs, and environmental (e.g., nutritional) conditions. As such, this function is sensitive to and closely connected with other relevant bodily systems, including reproduction and gonadal function. The aim of this mini-review article is to summarize the most salient experimental data supporting a role of the amygdala as a key brain region for emotional learning and behavior, including reward processing, in the physiological control of feeding and energy balance. In particular, a major focus will be placed on the putative interplay between reproductive signals and amygdala pathways, as it pertains to the control of metabolism, as complementary, extrahypothalamic circuit for the integral control of energy balance and gonadal function.

Molecular diagnosis of polycystic ovary syndrome in obese and non-obese women by targeted plasma miRNA profiling.

OBJECTIVE: Polycystic ovary syndrome (PCOS) is diagnosed based on the clinical signs, but its presentation is heterogeneous and potentially confounded by concurrent conditions, such as obesity and insulin resistance. miRNA have recently emerged as putative pathophysiological and diagnostic factors in PCOS. However, no reliable miRNA-based method for molecular diagnosis of PCOS has been reported. The aim of this study was to develop a tool for accurate diagnosis of PCOS by targeted miRNA profiling of plasma samples, defined on the basis of unbiased biomarker-finding analyses and biostatistical tools. METHODS: A case-control PCOS cohort was cross-sectionally studied, including 170 women classified into four groups: non-PCOS/lean, non-PCOS/obese, PCOS/lean, and PCOS/obese women. High-throughput miRNA analyses were performed in plasma, using NanoString technology and a 800 human miRNA panel, followed by targeted quantitative real-timePCR validation. Statistics were applied to define optimal normalization methods, identify deregulated biomarker miRNAs, and build classification algorithms, considering PCOS and obesity as major categories. RESULTS: The geometric mean of circulating hsa-miR-103a-3p, hsa-miR-125a-5p, and hsa-miR-1976, selected among 125 unchanged miRNAs, was defined as optimal reference for internal normalization (named mR3-method). Ten miRNAs were identified and validated after mR3-normalization as differentially expressed across the groups. Multinomial least absolute shrinkage and selection operator regression and decision-tree models were built to reliably discriminate PCOS vs non-PCOS, either in obese or non-obese women, using subsets of these miRNAs as performers. CONCLUSIONS: We define herein a robust method for molecular classification of PCOS based on unbiased identification of miRNA biomarkers and decision-tree protocols. This method allows not only reliable diagnosis of non-obese women with PCOS but also discrimination between PCOS and obesity. CAPSULE: We define a novel protocol, based on plasma miRNA profiling, for molecular diagnosis of PCOS. This tool not only allows proper discrimination of the condition in non-obese women but also permits distinction between PCOS and obesity, which often display overlapping clinical presentations.

Congenital ablation of Tacr2 reveals overlapping and redundant roles of NK2R signaling in the control of reproductive axis.

Tachykinin (TAC) signaling is an important element in the central control of reproduction. TAC family is mainly composed of substance P (SP), neurokinin A (NKA), and NKB, which bind preferentially to NK1, NK2, and NK3 receptors, respectively. While most studies have focused on the reproductive functions of NKB/NK3R, and to a lesser extent SP/NK1R, the relevance of NK2R, encoded by Tacr2, remains poorly characterized. Here, we address the physiological roles of NK2R in regulating the reproductive axis by characterizing a novel mouse line with congenital ablation of Tacr2. Activation of NK2R evoked acute luteinizing hormone (LH) responses in control mice, similar to those of agonists of NK1R and NK3R. Despite the absence of NK2R, Tacr2-/- mice displayed only partially reduced LH responses to an NK2R agonist, which, nonetheless, were abrogated after blockade of NK3R in Tacr2-/- males. While Tacr2-/- mice displayed normal pubertal timing, LH pulsatility was partially altered in Tacr2-/- females in adulthood, with suppression of basal LH levels, but no changes in the number of LH pulses. In addition, trends for increase in breeding intervals were detected in Tacr2-/- mice. However, null animals of both sexes were fertile, with no changes in estrous cyclicity or sex preference in social behavioral tests. In conclusion, stimulation of NK2R elicited LH responses in mice, while congenital ablation of Tacr2 partially suppressed basal and stimulated LH secretion, with moderate reproductive impact. Our data support a modest, albeit detectable, role of NK2R in the control of the gonadotropic axis, with partially overlapping and redundant functions with other tachykinin receptors.NEW & NOTEWORTHY We have explored here the impact of congenital ablation of the gene (Tacr2) encoding the tachykinin receptor, NK2R, in terms of neuroendocrine control of the reproductive axis, using a novel Tacr2 KO mouse line. Our data support a modest, albeit detectable, role of NK2R in the control of the gonadotropic axis, with partially overlapping and redundant functions with other tachykinin receptors.

Effectiveness and safety of a glutaraldehyde-modified, L-tyrosine-adsorbed and monophosphoryl lipid A-Adjuvanted allergen immunotherapy in patients with allergic asthma sensitized to olive pollen: A retrospective, controlled real-world study.

BACKGROUND: Allergy to olive pollen is one of the primary causes of allergic asthma in Spain. Even though allergen immunotherapy (AIT) has shown clinical benefits in patients sensitized to different allergens, studies in asthmatic patients sensitized to olive pollen are insufficient. OBJECTIVE: To assess the effectiveness and safety of an ultra-short course of AIT with an L-tyrosine-adsorbed and monophosphoryl lipid A-adjuvanted olive pollen and olive/grass pollen extract (Pollinex Quattro®) in patients with allergic asthma in the real-world setting. METHODS: Retrospective, controlled study including patients with asthma, with and without allergic rhinitis, caused by sensitization to olive pollen from 11 centers in Spain. Patients received out-of-season (October-March) treatment with AIT in addition to their pharmacological treatment (active group) or pharmacological treatment (control group). Effectiveness variables, including unscheduled visits to the healthcare center, emergency room admissions, symptoms of asthma and rhinitis (following GEMA and ARIA classifications, respectively), and use of medication to treat asthma and rhinitis during the subsequent pollen season were compared between treatment groups. RESULTS: Of 131 study patients, 42 were treated with their usual asthma medication (control group) and 89 were treated with AIT (active group), either Pollinex Quattro® 100% olive pollen (n = 43, 48.3%) or 50% olive pollen/50% grass pollen (n = 46, 51.7%). Patients' demographic and clinical characteristics were similar between groups. The mean (SD) number of unscheduled visits to a healthcare center and emergency room admissions due to allergy symptoms was 2.19 (1.40) and 0.43 (0.63) in the control group, and 1.09 (1.25) and 0.11 (0.51) in the active group (P = 0.001 and P = 0.006, respectively). Severity and control of asthma symptoms remained unchanged (P = 0.347 and P = 0.179, respectively), rhinitis type improved (P = 0.025), and severity remained unchanged in the active compared to the control group. The use of short-acting beta-agonists and inhaled corticosteroids to treat asthma symptoms decreased in the active vs. the control group (P = 0.001 and P = 0.031, respectively). Twelve (13.5%) and two (2.2%) patients in the active group experienced local adverse reactions (edema, swelling, erythema, hives, pruritus, and heat), and systemic adverse reactions (hypertensive crisis and low-grade fever) to AIT, respectively; none was serious. CONCLUSION: AIT with Pollinex Quattro® specific for olive pollen and olive/grass pollens resulted in reduced visits to the healthcare center and emergency room and the use of asthma medication during the pollen season, indicating that this treatment was safe and effective in treating asthma in patients sensitized to these pollens.

Central Ceramide Signaling Mediates Obesity-Induced Precocious Puberty.

Childhood obesity, especially in girls, is frequently bound to earlier puberty, which is linked to higher disease burden later in life. The mechanisms underlying this association remain elusive. Here we show that brain ceramides participate in the control of female puberty and contribute to its alteration in early-onset obesity in rats. Postnatal overweight caused earlier puberty and increased hypothalamic ceramide content, while pharmacological activation of ceramide synthesis mimicked the pubertal advancement caused by obesity, specifically in females. Conversely, central blockade of de novo ceramide synthesis delayed puberty and prevented the effects of the puberty-activating signal, kisspeptin. This phenomenon seemingly involves a circuit encompassing the paraventricular nucleus (PVN) and ovarian sympathetic innervation. Early-onset obesity enhanced PVN expression of SPTLC1, a key enzyme for ceramide synthesis, and advanced the maturation of the ovarian noradrenergic system. In turn, obesity-induced pubertal precocity was reversed by virogenetic suppression of SPTLC1 in the PVN. Our data unveil a pathway, linking kisspeptin, PVN ceramides, and sympathetic ovarian innervation, as key for obesity-induced pubertal precocity.

Potential impacts of horizontal gene transfer on human health and physiology and how anthropogenic activity can affect it.

Horizontal gene transfer (HGT) is widespread among prokaryotes driving their evolution. In this paper, we review the potential impact in humans of the HGT between prokaryotes living in close association with humans in two scenarios: horizontal transfer in human microbiomes and transfer between microbes living in human managed environments. Although our vision is focused on the possible impact of these transfers in the propagation of antibiotic resistance genes or pathogenicity determinants, we also discuss possible human physiological adaptations via gene transfer between resident and occasional bacteria in the human microbiome.

Pediatric patient with diagnosis of extra osseous Ewing's sarcoma of the tongue: case report / Paciente pediátrico com diagnóstico de sarcoma de Ewing extra-ósseo em língua: relato de caso

ABSTRACT Ewing's sarcoma is a malignant tumor that arises mainly from bone tissue, so that its extra-osseous presentation is not very common and even more unusual, in the soft tissues of the oral cavity. The objective of this case was to describe the clinical characteristics of an extra-osseous Ewing's Sarcoma of the tongue in a pediatric patient. An 11-year-old male school patient, who attended an oral medicine consultation referring a volume increase in the tongue. Intraorally, a tumoral lesion was observed on the left lateral edge of the tongue, indurated, with the same color of the mucosa with ulcerated areas, well defined edges and symptomatic on palpation, with an approximate size of 2.5 cm. A cervical and maxillofacial MRI was indicated, observing a partially delimited hyperintense and non-infiltrating lesion in the described area. An incisional biopsy was performed with histopathological diagnosis of malignant neoplasm of blue round cells, theCD99 marker was found to be positive in the immunohistochemical study and was key to the definitive diagnosis of this tumor. A thoraco-abdomino-pelvic tomography was requested by the Pediatric Oncology service, as well as biopsy and aspiration of bone marrow, in which no neoplastic infiltrations were evidenced. After four cycles of chemotherapy, total removal of the lesion was performed with a consecutive histopathological study of the surgical piece, indicating free edges of the lesion. Ewing's sarcoma is a tumor with aggressive behavior, so this case represents a finding of clinical and epidemiological relevance, both due to its extra-osseous appearance and its unusual behavior.

RESUMO O sarcoma de Ewing é um tumor maligno que surge principalmente de tecido ósseo, pelo qual sua apresentação extra-óssea não é muito comum, sendo ainda mais raro seu aparecimento em tecidos moles da cavidade bucal. O objetivo deste caso foi descrever as características clínicas de um Sarcoma de Ewing extra-ósseo em língua em paciente pediátrico. Refere-se a paciente escolar masculino de 11 anos de idade, quem acudiu a consulta de Medicina Bucal referindo um aumento de volume em língua. Intraoralmente observou-se lesão tumoral em borda lateral esquerda de língua, indurada, da mesma cor da mucosa com áreas ulceradas e bordas bem definidas, de aproximadamente 2,5cm. Foi indicada uma ressonância magnética cervical e maxilofacial, observando-se uma lesão hiperintensa, parcialmente delimitada e não infiltrante na zona descrita. Realizou-se biópsia incisional com diagnóstico histopatológico de Neoplasia maligna de células redondas azuis, o marcador de imunohistoquímica CD99, encontrado positivo neste caso foi chave para o diagnóstico definitivo. Uma tomografia abdominotorácico-pélvico foi requerida pelo serviço de Oncologia Pediátrica, além de aspirado e biópsia de medula óssea, nos quais não se evidenciaram infiltrações neoplásicas. Após quatro ciclos de quimioterapia, realizou-se a cisão da lesão e consecutivo estudo da peça cirurgica, indicando bordas livres de lesão. O sarcoma de Ewing é um tumor de comportamento agressivo, pelo qual este caso representa um achado de relevância clínica e epidemiológica, tanto por sua aparição extra-óssea quanto por seu comportamento inusual.

Metabolic regulation of female puberty via hypothalamic AMPK-kisspeptin signaling.

Conditions of metabolic distress, from malnutrition to obesity, impact, via as yet ill-defined mechanisms, the timing of puberty, whose alterations can hamper later cardiometabolic health and even life expectancy. AMP-activated protein kinase (AMPK), the master cellular energy sensor activated in conditions of energy insufficiency, has a major central role in whole-body energy homeostasis. However, whether brain AMPK metabolically modulates puberty onset remains unknown. We report here that central AMPK interplays with the puberty-activating gene, Kiss1, to control puberty onset. Pubertal subnutrition, which delayed puberty, enhanced hypothalamic pAMPK levels, while activation of brain AMPK in immature female rats substantially deferred puberty. Virogenetic overexpression of a constitutively active form of AMPK, selectively in the hypothalamic arcuate nucleus (ARC), which holds a key population of Kiss1 neurons, partially delayed puberty onset and reduced luteinizing hormone levels. ARC Kiss1 neurons were found to express pAMPK, and activation of AMPK reduced ARC Kiss1 expression. The physiological relevance of this pathway was attested by conditional ablation of the AMPKα1 subunit in Kiss1 cells, which largely prevented the delay in puberty onset caused by chronic subnutrition. Our data demonstrate that hypothalamic AMPK signaling plays a key role in the metabolic control of puberty, acting via a repressive modulation of ARC Kiss1 neurons in conditions of negative energy balance.

Vasopressin casts light on the suprachiasmatic nucleus.

KEY POINTS: A subpopulation of retinal ganglion cells expresses the neuropeptide vasopressin. These retinal ganglion cells project predominately to our biological clock, the suprachiasmatic nucleus (SCN). Light-induced vasopressin release enhances the responses of SCN neurons to light. It also enhances expression of genes involved in photo-entrainment of biological rhythms. ABSTRACT: In all animals, the transition between night and day engages a host of physiological and behavioural rhythms. These rhythms depend not on the rods and cones of the retina, but on retinal ganglion cells (RGCs) that detect the ambient light level in the environment. These project to the suprachiasmatic nucleus (SCN) of the hypothalamus to entrain circadian rhythms that are generated within the SCN. The neuropeptide vasopressin has an important role in this entrainment. Many SCN neurons express vasopressin, and it has been assumed that the role of vasopressin in the SCN reflects the activity of these cells. Here we show that vasopressin is also expressed in many retinal cells that project to the SCN. Light-evoked vasopressin release contributes to the responses of SCN neurons to light, and enhances expression of the immediate early gene c-fos in the SCN, which is involved in photic entrainment of circadian rhythms.

Amygdala Kisspeptin Neurons: Putative Mediators of Olfactory Control of the Gonadotropic Axis.

Kisspeptins and their receptors are potent regulators of the gonadotropic axis. Kisspeptin neurons are found mainly in the hypothalamic arcuate nucleus and the anteroventral periventricular nucleus. However, there is also a third population of kisspeptin neurons, located in the amygdala. We used fluorescence immunohistochemistry to quantify and localize the amygdala kisspeptin neurons and to reveal close apposition and putative innervations by vasopressinergic and tyrosine hydroxylase-positive dopaminergic neurons. Using microinjections of retro- and anterograde tracers, and viral transfection systems in rats and transgenic mice, we showed reciprocal connectivity between the accessory olfactory bulb and the amygdala kisspeptin neurons. In vitro recordings indicate an inhibitory action of kisspeptin on mitral cells in the accessory olfactory bulb. Using viral specific-cell gene expression in transgenic mice in combination with double immunofluorescence histochemistry, we found that the amygdala kisspeptin neurons also project to gonadotropin-releasing hormone (GnRH) neurons in the preoptic area. Our neuroanatomical and electrophysiological data suggest that amygdala kisspeptin neurons integrate social behaviour and odour information into GnRH neurons in the preoptic area to coordinate the gonadotropic axis and the appropriate output behaviour to odour cues.

Defining a novel leptin-melanocortin-kisspeptin pathway involved in the metabolic control of puberty.

OBJECTIVE: Puberty is a key developmental phenomenon highly sensitive to metabolic modulation. Worrying trends of changes in the timing of puberty have been reported in humans. These might be linked to the escalating prevalence of childhood obesity and could have deleterious impacts on later (cardio-metabolic) health, but their underlying mechanisms remain unsolved. The neuropeptide α-MSH, made by POMC neurons, plays a key role in energy homeostasis by mediating the actions of leptin and likely participates in the control of reproduction. However, its role in the metabolic regulation of puberty and interplay with kisspeptin, an essential puberty-regulating neuropeptide encoded by Kiss1, remain largely unknown. We aim here to unveil the potential contribution of central α-MSH signaling in the metabolic control of puberty by addressing its role in mediating the pubertal effects of leptin and its potential interaction with kisspeptin. METHODS: Using wild type and genetically modified rodent models, we implemented pharmacological studies, expression analyses, electrophysiological recordings, and virogenetic approaches involving DREADD technology to selectively inhibit Kiss1 neurons, in order to interrogate the physiological role of a putative leptin→α-MSH→kisspeptin pathway in the metabolic control of puberty. RESULTS: Stimulation of central α-MSH signaling robustly activated the reproductive axis in pubertal rats, whereas chronic inhibition of melanocortin receptors MC3/4R, delayed puberty, and prevented the permissive effect of leptin on puberty onset. Central blockade of MC3/4R or genetic elimination of kisspeptin receptors from POMC neurons did not affect kisspeptin effects. Conversely, congenital ablation of kisspeptin receptors or inducible, DREADD-mediated inhibition of arcuate nucleus (ARC) Kiss1 neurons resulted in markedly attenuated gonadotropic responses to MC3/4R activation. Furthermore, close appositions were observed between POMC fibers and ARC Kiss1 neurons while blockade of α-MSH signaling suppressed Kiss1 expression in the ARC of pubertal rats. CONCLUSIONS: Our physiological, virogenetic, and functional genomic studies document a novel α-MSH→kisspeptin→GnRH neuronal signaling pathway involved in transmitting the permissive effects of leptin on pubertal maturation, which is relevant for the metabolic (and, eventually, pharmacological) regulation of puberty onset.

60 YEARS OF NEUROENDOCRINOLOGY: The posterior pituitary, from Geoffrey Harris to our present understanding.

Geoffrey Harris pioneered our understanding of the posterior pituitary, mainly with experiments that involved the electrical stimulation of the supraoptico-hypophysial tract. In the present essay, we explain how his observations included clues to the pulsatile nature of the oxytocin signal - clues that were followed up by subsequent workers, including his students and their students. These studies ultimately led to our present understanding of the milk-ejection reflex and of the role of oxytocin in parturition. Discoveries of wide significance followed, including: the recognition of the importance of pulsatile hormone secretion; the recognition of the importance of stimulus-secretion coupling mechanisms in interpreting the patterned electrical activity of neurons; the physiological importance of peptide release in the brain; the recognition that peptide release comes substantially from dendrites and can be regulated independently of nerve terminal secretion; and the importance of dynamic morphological changes to neuronal function in the hypothalamus. All of these discoveries followed from the drive to understand the milk-ejection reflex. We also reflect on Harris's observations on vasopressin secretion, on the effects of stress, and on oxytocin secretion during sexual activity.