Journal of Neuroendocrinology

Identifying the neural circuits engaged and reshaped by chronic stress is critical for understanding how adaptive responses shift to maladaptive behaviors that contribute to stress-related disorders. Our previous work demonstrates that chronic unpredictable stress (CUS) induces a persistent increase in the firing activity of proopiomelanocortin (POMC) neurons in the arcuate nucleus (ARC). This hyperactivity is due, in part, to a reduction in GABAergic synaptic transmission onto POMC neurons, indicating a disruption in inhibitory control. However, the sources of GABAergic inputs responsible for this effect of chronic stress are unknown. Although AgRP neurons provide local GABAergic input onto POMC neurons and are suppressed by chronic stress, chemogenetic activation of AgRP neurons during stress exposure failed to reduce POMC neuron hyperactivity. GABAergic projections originating from the dorsomedial hypothalamus (DMH) represent another source of inhibitory input to POMC neurons. We found that CUS decreased the firing activity of DMH GABAergic neurons with sex differences, with females exhibiting greater vulnerability to stress-induced suppression. Chemogenetic activation of these neurons during chronic stress markedly attenuated POMC neuron hyperactivity in both sexes, indicating that DMH GABAergic neurons function as a critical upstream regulator of POMC neuron activity under chronic stress. These findings suggest that reduced inhibitory input from DMH GABAergic neurons, rather than local GABAergic AgRP neurons, drives POMC neuron hyperactivity. The weakening of the DMHGABA[->]ARCPOMC circuit activity may represent a novel mechanism underlying maladaptive stress responses and a potential therapeutic target for stress-related disorders.

The signaling pathways that control embryonic development, migration, and differentiation of gonadotropin-releasing hormone (GnRH) neurons, as well as the postnatal fate, function, and survival of differentiated cells, are the subject of ongoing research. Here, we examined the role of phosphoinositides in this complex multistep process by generating GnRH neuron-specific phosphatidylinositol 4-kinase alpha knockout mice. These mice were healthy and indistinguishable from their control littermates in size. However, adult knockout females and males were infertile due to underdeveloped gonads and reproductive organs. Furthermore, hypothalamic GnRH immunoreactivity was absent, and expression of the hypothalamic Gnrh1 gene and pituitary gonadotroph-specific genes was reduced. In contrast, hypothalamic kisspeptin immunoreactivity was preserved, and Kiss1 expression was modified in a nuclei specific-manner, consistent with the loss of circulating sex steroid hormones. Embryonic neurogenesis and migration of GnRH neurons were not impaired, as evidenced by normal Gnrh1 expression in the hypothalamus of neonatal animals and the presence of immunoreactive GnRH neurons in infantile mice in comparable number and distribution to age-matched controls. However, their cellular degeneration was evident, accompanied by reduced Gnrh1 expression. GnRH neuron-specific tdTomato expression confirmed their postnatal degeneration and death, whereas ectopic tdTomato cells located in the lateral septum remained unaffected. Together, these findings indicate that phosphoinositides dependent on phosphatidylinositol 4-kinase alpha activity are not critical for embryonic steps in the development of the GnRH neuronal network, but are essential for the postnatal function and survival of these cells. Significance StatementDifferentiation of neuroendocrine GnRH cells involves neurogenesis in the olfactory placodes, migration to the hypothalamus, projection to the median eminence, and connections with upstream neurons, including kisspeptin neurons. Here we show that knockout of phosphatidylinositol 4-kinase alpha in GnRH neurons does not affect these strps of embryonic development. However, the activity of this enzyme is essential for postnatal survival of GnRH neurons; in the absence of this gene, the neurons die, causing infertility in both female and male mice.

Vesicular glutamate transporter 3 (VGluT3) is expressed in a large subset of serotonin (5-HT) neurons of the dorsal raphe nucleus (DRN), suggesting a potential for glutamate co-transmission. Although VGluT3 has been implicated in the physiology of several non-glutamatergic neuronal populations, its specific role in the organization and function of 5-HT axons remains unclear. Here, we used CRISPR-Cas9 mediated knockdown and viral overexpression of VGluT3 in DRN 5-HT neurons of adult mice to assess its contribution to synaptic architecture in the lateral hypothalamus (LHA) and to 5-HT-related behaviors. VGluT3 depletion did not significantly alter synaptic incidence or organization of 5-HT DRN terminals in the LHA. In contrast, VGluT3 overexpression increased the proportion of asymmetric synapses without changing the overall synaptic incidence. In behavioral assays, VGluT3 depletion impaired motor coordination and increased anxiety-like, repetitive, and social behavior, whereas VGluT3 overexpression selectively reduced repetitive behavior. Basal locomotion and depressive-like behaviors were unchanged by either manipulation. Together, these findings indicate that VGluT3 modulates both the structural organization and behavioral output of DRN 5-HT neurons, supporting a modulatory role for VGluT3-dependent signaling within 5-HT circuits.

Astrocytes are now widely recognized as important modulators of synaptic plasticity and socio-emotional behaviors. Recent studies highlight their involvement in anxiety- and depressive-like behaviors, particularly via oxytocin (OXT) signaling. While the specific contributions of astrocytes remain largely unexplored, the role of OXT receptor (OXTR) signaling in the lateral septum (LS) in regulating social fear expression has been well characterized. Here, we studied the differential contribution of astrocytic OXTR signaling using a social fear conditioning (SFC+) paradigm. We found the highest abundance of astrocytes, and especially of OXTR-expressing (OXTR+) astrocytes, within the caudal LC (LSc) compared to the rostral LS in both male and female mice. Interestingly, female mice displayed a significantly higher number of astrocytes and OXTR+ astrocytes in the LSc in comparison to males. However, social fear acquisition resulted in dynamic changes in LSc astrocytic morphology and calcium activity in male mice. Furthermore, we showed that pre-SFC acquisition pharmacology-induced loss of local astrocytic function facilitated the extinction of social fear in males. In support, astrocyte-specific OXTR knockdown in the LSc also facilitated social fear extinction in both males and females. Taken together, our study identifies OXTR-signaling in LSc astrocytes as a crucial component in the mechanisms underlying the regulation of social fear in a sex-dependent manner.

Chronic stress increases risk for metabolic disorders, including diabetes mellitus. Additionally, projections from the infralimbic cortex (IL) to the rostral ventrolateral medulla (RVLM) regulate endocrine stress responses. However, the neurobiological basis for chronic stress effects on glucose homeostasis has not been identified. The current study tests the hypothesis that the IL-RVLM circuit is necessary to prevent glucose intolerance. Accordingly, male and female rats with Cre-dependent expression of tetanus toxin light chain (TeLC) to inhibit neurotransmitter release from RVLM-projecting IL neurons were subject to chronic variable stress (CVS) or remained as No CVS controls. Animals were then acutely challenged with a fasted intraperitoneal glucose tolerance test (GTT). Endocrine metabolic function was evaluated during GTT via time courses of glucose, insulin, glucagon, and corticosterone. In No CVS females expressing TeLC, inhibition of IL-RVLM circuit signaling impaired glucose tolerance characterized by elevated glucose and decreased insulin sensitivity. Following chronic stress, females had impaired glucoregulation characterized by decreased glucose clearance and elevated corticosterone. When combined with TeLC, chronically-stressed females showed shifts in the ratio of insulin to glucagon compared to CVS GFP females, suggesting circuit function impacts the pancreatic mechanisms mediating glucose homeostasis during chronic stress. In No CVS males, TeLC increased glucagon only. However, CVS TeLC males had impaired glucose tolerance, reduced insulin sensitivity, and decreased corticosterone. These data indicate that the IL-RVLM circuit mediates glucoregulation in a manner dependent on both sex and stress history. Collectively, the IL-RVLM circuit is necessary for the sex-specific maintenance of glucose homeostasis following chronic stress.

Polycystic ovary syndrome (PCOS), a common cause of infertility, is marked by persistently high luteinizing hormone (LH)-pulse frequency, presumably driven by high-frequency GnRH pulses. Prenatally androgenized (PNA) mice mimic neuroendocrine PCOS symptoms including high LH-pulse frequency. GnRH neurons from adult PNA mice have a higher firing rate than those from vehicle (VEH) mice; this is reversed in prepubertal mice despite more excitatory inputs at both ages. We hypothesized voltage-gated Ca2+ currents (ICa) help set intrinsic excitability of GnRH neurons and are altered by development and/or PNA treatment. Whole-cell patch-clamp recordings were used to measure GnRH neuron ICa in 3wk-old and adult VEH and PNA mice. PNA treatment increased ICa density and depolarized the ICa-half inactivation potential at both ages. In VEH but not PNA mice, the Ca2+-half activation potential was depolarized in adults versus 3wks. Age decreased the inactivation rate of a fast ICa regardless of PNA treatment. GnRH neuron firing rate during current injections was higher at 3wks than in adulthood in VEH mice only. Blocking small-conductance Ca{superscript 2}-activated K current with apamin increased GnRH neuron firing rate except in adult PNA mice. Apamin changed the post-spike-train membrane response from hyperpolarization to depolarization; during development, this net effect of apamin became smaller in PNA mice. In summary, while GnRH neurons from PNA mice have increased ICa, they lack some developmental changes in ICa kinetics and intrinsic excitability observed in VEH mice. Ca{superscript 2}-activated K currents are less prominent in GnRH neurons from adult PNA mice, perhaps contributing to increased spontaneous firing. Significance statementHyperactivation of GnRH neurons, which control reproductive endocrine function, can lead to increased LH-pulse frequency and is a hallmark of hyperandrogenemia polycystic ovary syndrome (PCOS). We used a mouse model of prenatal androgenization (PNA) that recapitulates the neuroendocrine aspects of PCOS to test the role of calcium currents (ICa) in the PNA phenotype and the typical pubertal process. PNA treatment increased ICa in GnRH neurons both before and after puberty. Calcium plays a crucial role in neurosecretion thus this may enhance GnRH release. Another role of calcium is activation of calcium-sensitive potassium currents, which tend to decrease action potential firing rate. Despite increased ICa, calcium-activated potassium currents are less effective in adult PNA mice, perhaps contributing to GnRH neuron hyperactivation.

Kisspeptin neurons in the rostral hypothalamus are hypothesized to initiate preovulatory gonadotropin-releasing hormone (GnRH) surges by causing estradiol-dependent activation of GnRH neuron action potential firing and subsequent GnRH release. To determine if estradiol or ovarian cycle stage modulates functional connectivity in this circuit, we used optogenetics to photostimulate anteroventral-periventricular (AVPV) area kisspeptin neurons while recording electrical activity and/or evoked synaptic currents from preoptic area GnRH neurons in acutely-prepared mouse brain slices. Slices were prepared from mice in multiple hormonal states, including 2-days post ovariectomy (OVX) and OVX plus estradiol during the morning or afternoon, diestrus, proestrus and 1-week post OVX, and 6-weeks post OVX with or without 1 week of estradiol replacement. Photostimulation induced a sustained, frequency-dependent increase in GnRH neuron firing rate. This neuromodulatory-typical response was not different in diestrous vs proestrous mice but was blunted in 1-week OVX mice, suggesting ovarian steroids amplify this response. Neuromodulatory responses were infrequent in 6-week OVX mice even with 1-week of estradiol treatment. A minority of GnRH neurons exhibited a substantial and near-immediate increase in firing rate typical of fast synaptic transmission. Monosynaptic connectivity was low and stable across the hormone states tested and mediated by GABA. Interestingly, evidence of a monosynaptic connection was not a requirement for GnRH neurons to exhibit a sustained increase in firing rate, suggesting non-synaptic or volume transmission occurs in this system. Synaptic connectivity did, however, amplify the increase in firing rate observed in GnRH neurons from proestrous mice, indicating proestrous hormonal conditions can amplify this response. Significance statementOvulation is initiated by central positive feedback effects of estradiol stimulating a surge of gonadotropin-releasing hormone (GnRH) release. Estradiol feedback is conveyed to GnRH neurons by afferents expressing estrogen receptor alpha, including kisspeptin-expressing neurons in the anteroventral periventricular (AVPV) area. To determine if endocrine milieu modulates functional interactions between AVPV kisspeptin and GnRH neurons, optogenetics was used to stimulate AVPV kisspeptin neurons while recording GnRH neuron spiking activity or synaptic currents in brain slices from ovariectomized, estradiol-treated, and ovary-intact mice. Stimulation (20Hz) increased GnRH neuron firing rate in all hormone conditions. This effect was stronger during proestrus and was further increased in GnRH neurons receiving fast-synaptic transmission. A synaptic connection was not required, however, suggesting volume transmission occurs.

The population of kisspeptin neurons located in the rostral periventricular area of the third ventricle (RP3V) is thought to have a key role in generating the GnRH surge that triggers ovulation. Using a modified GCaMP fibre photometry procedure, we have been able to record the in vivo population activity of RP3VKISS neurons across the estrous cycle of female mice. A marked increase in GCaMP activity was detected beginning on the afternoon of proestrus that lasted in total for 13{+/-}1 hours. This was comprised of slow baseline oscillations with a period of 91{+/-}4 min and associated with high frequency rapid transients. Very little oscillating baseline or transient activity was detected at other stages of the estrous cycle. Concurrent blood sampling showed that the peak of the LH surge occurred 3.5{+/-}1.1 h after the first baseline RP3VKISS neuron baseline oscillation on the afternoon of proestrus. The time of onset of RP3VKISS neuron oscillations varied between mice and across subsequent proestrous stages in the same mice. To assess the impact of estradiol on RP3VKISS neuron activity, mice were ovariectomized and given an incremental estradiol replacement regimen. Minimal patterned GCaMP activity was found in OVX mice, and this was not changed acutely by any of the estradiol treatments. However, on the afternoon of the expected LH surge, the same oscillating baseline activity with associated transients occurred for 7.1{+/-}0.5 h. These observations reveal an unexpected prolonged oscillatory pattern of RP3VKISS neuron activity that is dependent on estrogen and underlies the preovulatory LH surge as well as potentially other facets of reproductive behavior.

Anorexia nervosa is characterized by maladaptive eating behavior and cognitive dysfunction, which could be explained by a neuroinflammation. A gut dysbiosis could link gastrointestinal alterations to central dysfunctions, particularly via the toll-like receptor 4 (TLR4), which has been shown to play a key role in the activity-based anorexia (ABA) model. We aimed to evaluate the neuroinflammation and its behavioral consequences in the ABA model, and to decipher the role of the microbiota-gut-brain axis, and more specifically of TLR4, in these alterations of the central nervous system. We show that chronic restriction is more strongly associated with gut inflammation, cecal microbiota alteration and neuroinflammatory processes in the hippocampus than acute restriction. The hippocampal glial response is characterized by a loss of astrocyte density, and an increased number of deramified microglia. We further demonstrate that these alterations are independent of TLR4 expressed by intestinal epithelial cells. In conclusion, our results highlight that the chronicity of ABA-associated undernutrition alters the response of glial cells in the hippocampus that is linked with changes in microbiota composition, highlighting the importance of faster diagnosis and treatment of AN.

The overlapping effects on neuronal plasticity of acute increase in glucocorticoid levels and the BDNF-TRKB signaling indicate a deep interconnection between the two pathways. Moreover, chronic stress with elevated glucocorticoids levels and downregulation of TRKB signaling associated with reduced BDNF are both involved in the pathophysiology of different psychiatric disorders. However, the mechanism by which TRKB and glucocorticoid receptors are recruited together in the modulation of neuronal plasticity is not clear yet. In this study we investigated the molecular mechanisms underlying the interplay of glucocorticoids and TRKB signaling in vitro and in vivo. We found that although not binding directly to TRKB, glucocorticoids promote TRKB dimerization and signaling similarly to BDNF. Moreover, the glucocorticoid receptor physically interacts with TRKB, modulating its dimerization and activity both in presence and in absence of glucocorticoids and contributing to TRKB-mediated plasticity. The transmembrane domain of TRKB is important for the interaction and for mediating the behavioral effects of TRKB and glucocorticoid receptor modulation, suggesting at least a partial overlap between the two signaling pathways. These results shed light on the interconnected effects of glucocorticoid and TRKB signaling highlighting the need for a more comprehensive understanding of the role and the dysfunction of different players contributing to synaptic plasticity.

Selectively bred diet-induced obesity-prone (DIO-P) rats have defective nutrient sensing prior to obesity onset. We hypothesized that glial inflammation in the arcuate nucleus (ARC) impairs hypothalamic responses to dietary clues, thereby promoting obesity development in genetically susceptible animals. This study established a timeline of inflammatory events in male and female DIO-P and diet-resistant (DR) rats fed either a low fat chow or exposed to a high energy diet (HED; 32% fat, 25% sucrose) for three days or four weeks. On chow diet, DIO-P rats of both sexes displayed elevated astrocyte density and increased expression of pro-inflammatory markers in the ARC, alongside reduced microglial content, compared to DR rats. Three days of HED transiently amplified most MBH pro-inflammatory markers in DIO-P rats. Four weeks of HED decreased GFAP expression in DIO-P rats while Iba1 density remained unchanged, whereas, DR rats showed a reduction in Iba1with no change in GFAP or cytokine expression. To determine whether mediobasal hypothalamus (MBH) astrocyte inflammation contributes to the development and maintenance of an obesity, astrocytic IKK{beta} was depleted before or after HED exposure. Prophylactic MBH astrocyte-specific IKK{beta} knockdown prevented subsequent body weight gain, improved glucose tolerance and decreased leptin levels in DIO-P rats to levels comparable to DR rats, with no effect in the latter. In contrast, MBH IKK{beta} astrocytic depletion in already obese DIO-P rats had no effect on energy homeostasis. Together, these findings validate the DIO-P rat as a polygenic model of obesity predisposition and demonstrate that preventing ARC astrogliosis is sufficient to HED-induced body weight gain and obesity development in genetically susceptible animals, highlighting MBH inflammation as a marker and driver of obesity predisposition. HighlightsO_LIChow-fed DIO-P rats present heightened ARC astrogliosis and cytokine expression preceding HED-induced obesity. C_LIO_LIInhibition of IKK{beta} in MBH astrocytes prevents DIO-P rats from becoming obese. C_LIO_LIOnce obese, inhibition of IKK{beta} in MBH astrocytes is not sufficient to reverse the obese phenotype. C_LI

BackgroundAdrenal steroid hormone production is essential for systemic stress adaptation and metabolic homeostasis, and it is tightly regulated by oxygen availability. Previously, we demonstrated that acute hypoxia suppresses adrenal steroidogenesis through HIF-1-dependent induction of microRNAs (miRNAs) that target key steroidogenic enzymes. However, the mechanisms by which HIF-1 controls miRNA expression and activity in this context remain unclear. MethodsTo address this issue, we mapped the genome-wide HIF-1 binding landscape in murine adrenocortical cells using Cleavage Under Targets & Tagmentation (CUT&Tag). We integrated this data with gene expression analyses following pharmacological HIF-1 stabilization, physiological hypoxia, and genetic HIF-1 depletion to distinguish HIF-1-dependent effects from broader hypoxia-driven responses. ResultsWe detected HIF-1 binding at loci encoding steroidogenic enzymes and steroidogenesis-associated miRNAs. Unexpectedly, we also detected binding at genes involved in miRNA biogenesis and function, including components of the nuclear microprocessor complex and the cytoplasmic RNA-induced silencing complex (RISC). Functional analyses revealed that hypoxia broadly represses the expression of miRNA-processing genes through both HIF-1-dependent and -independent mechanisms. Notably, HIF-1 selectively modulated or counteracted this repression in a gene-specific manner, indicating a regulatory role beyond direct transcriptional activation. ConclusionsThese findings reveal an unrecognized layer of hypoxia-driven cell communication, wherein HIF-1 coordinates the transcriptional and post-transcriptional regulation of adrenal steroidogenesis by shaping the miRNA-processing landscape. This work extends our understanding of how oxygen-sensitive signaling pathways integrate gene expression and RNA-based regulatory mechanisms to control endocrine function.

Male odor induces various behavioral and physiological responses across the reproductive cycle in female mice. Although male odor preference in females is reduced during pregnancy, how it changes across later stages of the reproductive cycle, including nursing and weaning, remains unclear. Here, we found that male odor preference is lost during pregnancy and nursing. To identify the olfactory systems involved in these changes, we examined neural activity using c-Fos immunohistochemistry. Male odor exposure during nursing increased neural activity in the accessory olfactory bulb and the posteroventral medial amygdala (MeApv), a key node of the accessory olfactory system, as well as in subdivisions of the central amygdala, but not in the ventromedial hypothalamus or the bed nucleus of the stria terminalis. Finally, lesions of the MeApv prevented the loss of male preference during nursing, indicating that the MeApv is required for suppression of male preference during this stage.

Pacific salmon (Oncorhynchus spp.) undergo intricate physiological changes during maturation as they migrate to spawning beds and breed before succumbing to a programmed senescence (semelparous life cycle). Research into the physiological mechanisms of semelparity in salmon has identified a clear and progressive rise in sex and stress hormone levels throughout their migration, which correlates with the emergence of morphological traits, as well as changes in behavioral patterns. We examined transcriptional changes in three critical tissues (gonads, head kidney, and skeletal muscle) across the spawning migration in male and female Pink salmon (Oncorhynchus gorbuscha) to capture the molecular changes occurring in these tissues during maturation and senescence. Major transcriptional changes occurred around the time of spawning, while only modest transcriptional changes were found as the fish migrated between saltwater and freshwater. Examination of enriched biological pathways identified the signatures of semelparous catabolic processes in all tissues and a strong immune response in somatic tissues. Evidence of shifts in lipid energy mobilization were also seen in somatic tissues. A closer investigation of the expression patterns of endocrine hormone receptors showed that many endocrine pathways prioritized expression of specific dominant ohnologs to orchestrate much of the hormone response in the analyzed tissues. Our characterization of the transcriptional profiles in migrating pink salmon adds critical context to link the molecular changes occurring in tissues to the physiological transitions that define semelparous maturation in Pacific salmon. NEW & NOTEWORTHYLarge transcriptional changes occurred in the gonads, head kidney, and skeletal muscle of pink salmon during the final stages of their spawning migration. Across the tissues and sexes, spawning was marked by coordinated activation of catabolic programs (autophagy, proteolysis, cell death), and a strong immune response in somatic tissues, alongside lipid mobilization. Endocrine receptor expression analyses revealed that the response to hormones was primarily mediated by a limited number of dominant ohnologs.

Anorexia nervosa (AN) is a debilitating, often lethal, restrictive-type eating disorder without an effective cure. The underlying neural basis of AN has remained elusive without an animal model that has represented all typical AN symptoms. Here we show that aberrant activation of mediobasal hypothalamic (MBH) glutamatergic neurons led to lethal self-starvation, hyperactivity, anhedonia, social phobia, and increased anxiety, all of which represent typical symptoms of AN. These symptoms were selectively exhibited by targeted activation of MBH neurons expressing steroidogenic factor (SF1) and estrogen receptor alpha (ERa). Moreover, the elicited AN symptoms by activation of MBH glutamatergic or SF1/ERa neurons were rescued by removing release of glutamate or brain-derived neurotrophic factor (BDNF) from these neurons. Importantly, BDNF overexpression in SF1/ERa neurons promoted typical AN symptoms, which were suppressed by removing glutamate release. Thus, our findings identify aberrantly enhanced BDNF and consequent augmented glutamate release from SF1/ERa neurons as a neural basis underlying AN.

Voltage-gated sodium channels (VGSCs) are conventionally described as heterotrimers composed of one alpha and two beta subunits. However, the patterns of co-expression of alpha- and beta-subunits in neurons remain unclear. In the present study, we report that alpha- (Nav1.1, Nav1.2, and Nav1.6) and beta- (beta-1 and beta-2) subunits are densely expressed in axon initial segments (AISs) of neurons in the neocortex, hippocampus and cerebellum at postnatal days 14-15 (P14-15) and 8-9 weeks (8-9W). These distributions are largely unique and partially overlapping among brain regions. Notably, in the neocortex and hippocampus, AISs of presumptive parvalbumin-positive inhibitory neurons are positive for Nav1.1 and beta-1, whereas those of excitatory ones are positive for Nav1.2 and beta-2. Similarly, AISs of cerebellar basket cells, which are inhibitory neurons, are positive for Nav1.1 and beta-1, whereas those of granule cells, which are excitatory neurons, are positive for Nav1.2 and beta-2. Nav1.6 is expressed in many of these neurons. Some subunits exhibited distinct distribution patterns at the two postnatal stages analyzed, possibly because of their developmental changes of subcellular localizations. Taken together, these results indicate that combinations of VGSC subunits are largely unique among different neuronal subpopulations. These findings provide a useful reference for understanding the distribution and interactions of VGSC subunits in the brain.

Bilaterian animals exhibit operational (functional) asymmetry--population-level, directional left-right differences in physiology and behavior, including responses to spatially symmetric environmental challenges. Whether such symmetry-to-asymmetry conversion can be driven at the systems level by neurohormonal regulators remains unclear. Here we tested whether a spatially symmetric neuroendocrine challenge--water deprivation (WD)--can elicit a directional left-right physiological response in rats using hindlimb postural asymmetry (HL-PA), a binary readout that quantifies left- versus right-sided hindlimb flexion. Twenty-four hours of WD induced robust HL-PA with right hindlimb flexion, revealed under anesthesia. The asymmetry persisted after complete thoracic spinal cord transection, suggesting that humoral signaling, rather than descending neural commands, may maintain the postural bias. Because dehydration recruits the hypothalamic-neurohypophysial arginine vasopressin (AVP) system, we next tested AVP receptor involvement. Both a V1B antagonist (SSR-149415) and a V1A/V2 antagonist (conivaptan) abolished WD-induced HL-PA, supporting an AVP-dependent mechanism that likely operates at least two anatomical sites. AVP signaling may involve pituitary V1B-dependent endocrine output and spinal V1A actions; consistent with the latter, expression of AVP V1A receptors is right-biased in lumbar spinal cord. Together, these findings identify WD as a symmetric systemic challenge capable of imposing a directional peripheral set-point, and implicate vasopressin signaling in symmetry breaking and left-right physiological regulation. Visual summary O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/708998v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@10d6b3corg.highwire.dtl.DTLVardef@1fb4b5aorg.highwire.dtl.DTLVardef@11003c0org.highwire.dtl.DTLVardef@66671c_HPS_FORMAT_FIGEXP M_FIG C_FIG

Menopausal hormone therapy (MHT) is prescribed for climacteric symptoms including hot flushes and weight gain and contains estrogens such as 17 beta-estradiol (17{beta}E2). However, estrogen receptor activation by MHT may increase reproductive cancers and cardiovascular event risk in some people. As the protective metabolic effects of 17{beta}E2 are partly mediated through the arcuate nucleus of the hypothalamus, restricting 17{beta}E2 actions to the brain could serve as a safer mechanism of MHT. 10{beta},17{beta}-Dihydroxyestra-1,4-dien-3-one (DHED) is a prodrug of 17{beta}E2 which is enzymatically converted to the parent hormone exclusively within the brain. DHED has demonstrated positive benefit in rodent models of centrally-mediated maladies including hot flushes, depression and cognitive decline, without peripheral hormonal burden. Therefore, we hypothesized that DHED treatment in obese female mice would act within the hypothalamus to provide the same beneficial metabolic effects as 17{beta}E2. Female mice were ovariectomized, placed on a high fat diet and split into either control, DHED, or 17{beta}E2 treatment groups. Body weight, uterus weight and glucose tolerance were recorded along with gonadal hormone receptor expression in the brain. Delivery of DHED at a similar dose as 17{beta}E2 failed to improve metabolic parameters or recapitulate the hypothalamic responses induced by 17{beta}E2. Delivery of DHED at higher doses, which elicited estrogen-like actions within the brain, still failed to improve metabolic health. Our findings suggest that peripheral actions, in addition to hypothalamic targets, may be required to mediate 17{beta}E2s protective effects on metabolism and that brain-targeted MHT may be unsuitable for improving metabolic health during menopause.

Anorexia nervosa is an eating disorder disproportionately found in female human teens and young adults. It is often resistant to treatment, has a significant chance of relapse and is more lethal than other eating disorders, such as bulimia nervosa or Avoidant/Restrictive Food Intake Disorder (ARFID). There is no specific medication for the treatment of anorexia nervosa. Treatment consists of psychosocial means, psychotherapy, psychoeducation, and nutritional counseling. Medication is usually used for treating comorbidities such as anxiety or to decrease obsessive-compulsive tendencies. These medications cannot help the patient regain weight or treat core symptoms. Metabotropic 2/3-glutamate (mGluR2/3) receptor agonist (LY379268) and antagonist (LY341495) are promising pharmacological agents to treat psychiatric disorders. Both agonists and antagonists have been reported to have anxiolytic effects in different animal models of anxiety, while antagonists have shown antidepressant-like effects in preclinical studies. The activity-based anorexia (ABA) paradigm is used to model anorexia nervosa. It consists of giving mice access to a running wheel and restricting their feeding time. This causes mice to exercise more than mice without feeding time restriction and to eat less than mice without access to a moving running wheel. In this study, we subcutaneously injected female ABA model mice with a metabotropic 2/3-glutamate receptor agonist (LY379268) and antagonist (LY341495) in two experiments. Both compounds exacerbated weight loss by decreasing food intake as well as increasing physical activity. It can be concluded that the manipulation of mGluR2/3 receptors is detrimental for the ABA model and likely for anorexia nervosa as well. HighlightsO_LImGluR2/3 agonist LY379268 decreases food intake and body weight of the ABA model C_LIO_LImGluR2/3 antagonist LY341495 decreases food intake and body weight of the ABA model C_LIO_LIBoth agonist and antagonist produce the effect within 48 hours C_LIO_LIBoth the agonist and antagonist are detrimental to the ABA-model C_LI

Emotion and mood regulation critically depends on interactions between the anterior cingulate cortex (ACC) and the amygdala. However, the detailed architecture of ACC projections to their major targets, the basal (BA) and accessory (AcBA) basal nuclei of the amygdala, remains unclear. To address this issue, a combined retrograde and anterograde tracing with viral vectors were performed in macaques to map the projection patterns from pregenual (pgACC), subgenual (sgACC), and dorsal (dACC) subareas. Data revealed that ACC neurons projecting to the BA arose predominantly from the superficial layers (II/III) of all subareas and the deep layers (V/VI) of the sgACC, whereas ACC neurons projecting to the AcBA originated mainly in the deep layers of the sgACC and dACC. The present study defines the topographic and layer-specific organization of ACC-amygdala connectivity in primates and subserves to provide an anatomical basis for future causal and translational approaches, such as targeted interventions against ACC-related mood disorders. TeaserPrimate anterior cingulate cortex has topographic and layer-specific projections to amygdala that are involved in emotion and mood regulation.