Journal of Neuroendocrinology最新文献

Glucocorticoids are produced through activation of the hypothalamic–pituitary–adrenal (HPA) axis, initiated by the release of corticotropin-releasing factor (CRF) from the hypothalamus. CRF acts through two receptor subtypes, CRF1 and CRF2. However, the specific contributions of CRF₁ and CRF₂ receptors to age-related changes in brain glucocorticoid activity remain largely unexplored. In certain tissues, including the hippocampus, glucocorticoid signaling is further amplified by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which regenerates inactive glucocorticoid metabolites into their active form. Notably, prior research investigating the role of hippocampal 11β-HSD1 in aging has focused exclusively on male subjects. In this study, we used genetic mouse models lacking functional CRF₁ or CRF₂ receptors to investigate their respective roles in regulating hippocampal 11β-HSD1 activity and glucocorticoid levels across age and sex. Mice of both sexes at 6 and 18 months of age were analyzed. Hippocampal 11β-HSD1 activity was assessed by measuring the ratio of corticosterone to dehydrocorticosterone using mass spectrometry in tissue extracts from CRF₁ and CRF₂ wild-type (WT), heterozygous (HET), and knockout (KO) mice. Our results demonstrate that hippocampal 11β-HSD1 activity increases with age in female CRF₁ WT and HET mice but not in CRF₁ KO females. In contrast, aged males exhibit elevated 11β-HSD1 activity regardless of CRF₁ genotype. In CRF₁ males, the age-related increase in hippocampal 11β-HSD1 activity is associated with higher hippocampal corticosterone levels, whereas in CRF₁ females, it corresponds with a decrease in hippocampal dehydrocorticosterone. CRF₁ deficiency leads to reduced hippocampal levels of both corticosterone and dehydrocorticosterone in males and females at both ages. CRF₁ deficiency is also associated with decreased plasma corticosterone levels in both male and female mice. Male, but not female, CRF₂ mice show an age-dependent increase in hippocampal 11β-HSD1 activity, which is not altered by CRF₂ deficiency. Moreover, CRF₂ deficiency results in increased plasma corticosterone in female, but not in male, mice. Overall, our findings reveal that hippocampal 11β-HSD1 activity increases with age in both sexes. In females, this increase is dependent on the presence of functional CRF₁ receptors. In contrast, males exhibit age-related increases in 11β-HSD1 activity independent of CRF₁ function. These findings underscore the importance of considering sex as a biological variable when developing therapeutic strategies targeting 11β-HSD1 to mitigate age-related memory decline.

During development, there is a significant sex difference in the expression of progestin receptor (PR) in the medial preoptic nucleus (MPN) of rodents. Males express high levels of PR immunoreactivity (PR-ir) in the MPN beginning at embryonic day 19, whereas PR is virtually absent in females until the second postnatal week. This sex difference indicates a developmental window during which the male MPN is more sensitive to progestins than the female MPN. The two PR isoforms, full-length PRB and the truncated PRA, can differentially regulate the expression of specific genes. Yet, it is unknown how these isoforms contribute to the sex difference in PR expression. In the present study, we investigated the relative contributions of PRA and PRB expression in the MPN during development. PR-ir in neonatal male and female PRA knockout (PRAKO) or PRBKO mice were compared with their wildtype (WT) counterparts. In the MPN, levels of PR-ir were higher in WT males than in WT females consistent with previous results from our lab. Moreover, this sex difference was also detected in both PRAKO and PRBKO mice, suggesting that both isoforms contribute to PR expression in males. We also investigated the expression of PRA and PRB in the ventrolateral subdivision of the ventromedial nucleus of the hypothalamus (VMN) and arcuate nucleus (ARC), two additional brain regions implicated in progestin function in reproduction in which males expressed PR at higher levels than females. Interestingly, in the VMN and the ARC, PRA was the predominant isoform. These findings suggest that the differential expressions of PRA and PRB result in sex differences in PR in the brain regions associated with sexually dimorphic behaviors and neuroendocrine functions.

The neurohypophysis is a major central neuroendocrine interface regulating reproductive functions and water homeostasis. Distinct neurovascular cell types interact via evolutionarily conserved signaling molecules in the developing neurohypophysis, providing a model system for studying principles in neuroendocrine interface morphogenesis. This review provides an overview of neurohypophysis development with a focus on paracrine signaling and the intrinsic mechanisms that regulate the major cell types and neurovascular interface development.

In species where males provide parental care, the transition to fatherhood involves a shift in life history strategy in the direction of increased parenting and decreased mating effort. In non-human mammals, the transition to parenthood involves an increase in the motivation to approach and care for offspring, which is mediated by changes in a neural system that includes the medial preoptic area and the mesolimbic dopamine system. Whether humans experience increased activity in this parental brain system with the transition to parenthood has not been established. Here, we use an effort-based decision-making task to longitudinally track changes in parenting and mating motivation, and functional MRI to track accompanying changes in brain function across the transition to first-time fatherhood in men and compare these changes with those found in a sample of non-father control males. Fathers were generally less willing than non-fathers to exert effort to view female stimuli; however, there were no apparent changes in motivation to engage with either infant or female stimuli across the transition to fatherhood. On the other hand, changes in brain activation were evident. In response to cues predicting infant pictures, new fathers showed a pre- to post-natal increase in activation of brain regions that are part of the mesolimbic dopamine system, and this change was not found in non-father male controls. Fathers, but not non-fathers, also showed increases in activation to infant stimuli in brain regions implicated in empathy, such as the anterior insula. While univariate analyses showed no significant change in the neural response to pictures of adult females among fathers, a multivariate brain signature that was previously found to classify pleasure responses to a wide range of stimuli revealed that fathers showed an increase in pleasure-related activity to infant stimuli, as well as a decrease in pleasure-related activity to female stimuli. Our findings suggest that human fathers experience neurofunctional changes that may adapt them to their new parental role.

Neurons in the arcuate nucleus of the hypothalamus (ARH) that coexpress kisspeptin, neurokinin B, and dynorphin (KNDy neurons) are considered the gonadotropin-releasing hormone (GnRH) pulse generator necessary for fertility. KNDy neurons are also metabolic sensors controlling the hypothalamic–pituitary-gonadal (HPG) axis. Insulin-like growth factor-1 (IGF-1) secretion is influenced by nutritional status and may serve as a cue detected by neurons to regulate various physiological processes, including reproduction. However, whether IGF-1 modulates KNDy neuron activity remains unclear. RNAscope was used to assess the number of kisspeptin neurons expressing the IGF-1 receptor (IGF1R). Additionally, the effects of IGF-1 on LH secretion, Kiss1 mRNA levels, intracellular calcium concentration ([Ca²⁺]i) in KNDy neurons, and resting membrane potential of kisspeptin neurons were investigated. Kisspeptin cells located at the ARH and anteroventral periventricular and rostral periventricular nuclei (here designated as AVPV) expressed the Igf1r in male and female mice. Intracerebroventricular IGF-1 administration acutely increased LH secretion without altering hypothalamic Kiss1 mRNA in male mice. In brain slices, IGF-1 administration elevated [Ca²⁺]i in KNDy cells of male mice and depolarized KNDy neurons in both sexes. IGF-1-induced depolarization was abolished by TTX and amino acid receptor antagonists, indicating an indirect mechanism. In contrast, IGF-1 has no effect on the RMP of AVPV kisspeptin neurons in female mice. IGF-1 acutely stimulates KNDy neuron activity via indirect effects despite Igf1r expression in these cells. These findings identify IGF-1 as a metabolic signal that modulates KNDy neuron excitability and, consequently, influences the reproductive axis.

Oxytocin is involved in the regulation of maternal behavior by binding to the oxytocin receptor (OXTR) in various parts of the brain. Our previous studies demonstrated that OXTRs are specifically expressed in the anteroventral periventricular nucleus (AVPV) of female mice, but not in male mice. Furthermore, the activity of the OXTR neurons is essential for proper expression of maternal behavior. The present study aimed to characterize two different populations of OXTR neurons found in the AVPV in the previous study: tyrosine hydroxylase immunoreactive (TH⁺) and non-TH immunoreactive (TH⁻) neurons. Whole-cell patch clamp recordings were used to observe the intrinsic electrophysiological properties of the OXTR neurons. TH⁺ neurons displayed a pacemaker-like intrinsic rhythmic short bursting activity, whereas TH⁻ neurons displayed either no firing at all, irregular firing, or phasic firing. Some TH⁻ OXTR neurons could switch back and forth among these firing patterns. The differences in the firing patterns between these two populations were likely derived from the difference in their expression of afterpotentials. TH⁺ OXTR neurons showed more depolarizing afterpotential (DAP) than after-hyperpolarization (AHP), while TH⁻ OXTR neurons exhibited more AHP than DAP. Activation of OXTR by a specific agonist caused a steady state depolarization and increase in Ca²⁺ transient resulting in changes in the firing activity in both TH⁺ and TH⁻ neurons. Lastly, biocytin was injected into the OXTR neurons during the whole-cell recordings to visualize the recorded neurons for immuno-identification of neuron type and morphological analysis. TH⁻ neurons displayed significantly more dendritic arborization than TH⁺ neurons. Therefore, TH⁺ and TH⁻ neurons are electrophysiologically and morphologically distinct. Moreover, because activation of OXTR caused a change in the firing activity of these neurons, oxytocin likely modulates the firing activity of both TH⁺ and TH⁻ OXTR neurons to influence maternal behavior.

The hypothalamic control of fertility is a quintessential homeostatic function. Given that reproduction is metabolically demanding, coordination between energy status and reproductive function is essential. Since GnRH neurons lack receptors for key metabolic hormones, nutrient sensing must occur via presynaptic neurons. Among the candidates are anorexigenic POMC and orexigenic NPY/AgRP neurons, both of which are in close apposition to the median eminence, a circumventricular organ permissive to circulating signals. These neurons are inversely regulated by glucose and metabolic hormones, with POMC neurons generally excited by insulin and leptin, and NPY/AgRP neurons inhibited by them. However, their synaptic input to GnRH neurons is sparse, and GnRH neurons may lack the necessary postsynaptic receptors. The discovery of kisspeptin neurons in the early part of this century revolutionized our understanding of reproductive regulation. These neurons project to and control GnRH neuronal excitability. More recently, arcuate kisspeptin neurons (KNDy) have been identified as the command neurons driving pulsatile release of GnRH and are essential for the GnRH/LH surge. Notably, these neurons express both steroid hormone receptors and metabolic hormone receptors and, like POMC neurons, are excited by insulin and leptin. Therefore, arcuate kisspeptin neurons likely serve as a central hub in linking metabolic signals with reproduction. This review will examine how these vital neurons control pulsatile GnRH release, their reciprocal synaptic connections with POMC and NPY/AgRP neurons, and how E2 can regulate their excitability. Through integration of metabolic and hormonal cues, these neurons help align reproductive capacity with the organism's energy status.

Neuroscience depends heavily on research done in mice (Mus musculus), yet the field has done little to address the chronic cold stress mice perpetually face during conventional “room temperature” housing (20°C–22°C). Contributions from other biomedical fields, such as immunology, oncology, and metabolic physiology, have shown that housing mice at room temperature substantially impacts broad and fundamental aspects of murine biology in ways that negatively affect the translational value of the research derived from these animals. Prairie voles (Microtus ochragaster) are an alternative small rodent model for neuroscience that are adapted for cold weather and better tolerate the ambient temperature of conventional housing. Here, we examined the effect of 3 days of housing at one of three ambient temperature conditions: 20°C, 25°C, or 30°C on oxytocin and vasopressin immunoreactivity within the paraventricular nucleus of the hypothalamus in both mice and voles. We found that increases in ambient temperature above 20°C led to a 32% reduction in oxytocin immunoreactivity in mice, while having no effect in voles. Vasopressin was unaffected in either species. Since oxytocin is a pleiotropic neuropeptide, responsible for regulating a number of homeostatic, emotional, and social circuits, this work calls into question whether findings from mice housed at 20°C can be reliably translated to humans living in thermoneutral conditions. This finding should spur further neuroscience research to reconcile how the assumptions of conventional housing have shaped murine neurobiology.

Prolactin is fundamental for pregnancy and lactation, and also has numerous metabolic roles including the stimulation of appetite. Mice with chronic hyperprolactinemia display increased food intake, enhanced expression of orexigenic genes in hypothalamic brain centers, and also develop obesity. Here, we tested whether the consumption of a rewarding high-fat diet (HFD) is altered in a mouse model of chronic hyperprolactinemia: LacDrd2KO mice, which lack dopamine Drd2 receptors in lactotrophs, preventing dopamine inhibition of prolactin secretion. We exposed control and LacDrd2KO mice to a binge-like eating protocol in which satiated mice have access to a HFD pellet for 2-h on four consecutive days. We found that both control and LacDrd2KO animals displayed binge-like eating of HFD, and that hyperprolactinemic mice nearly doubled their HFD intake compared to controls. Subsequently, we analyzed the activation of mesocorticolimbic brain nuclei involved in reward processing. We observed that, in response to HFD consumption, c-Fos levels were higher in dopaminergic neurons of the parabrachial pigmented area within the ventral tegmental area (VTA), a key brain center involved in reward regulation, and also in the core subdivision of the nucleus accumbens (Acb), the main target of dopaminergic VTA neurons. Furthermore, hyperprolactinemic mice had greater c-Fos activation in dopaminergic neurons of the VTA in response to HFD consumption, compared to control animals. Finally, c-Fos levels in the hypothalamic arcuate nucleus, mainly involved in the control of homeostatic food intake, were lower in LacDrd2KO mice and unaffected by HFD exposure. Current results suggest that chronic hyperprolactinemia is associated with increased consumption of a rewarding stimulus, engaging the activation of dopaminergic neurons in the VTA.

Early detection of metastases and timely surgical intervention play a crucial role in the management of neuroendocrine tumors. In large-sized pheochromocytomas and sympathetic paragangliomas (PPGL), functional imaging with positron emission tomography (PET) is recommended, as it improves the detection of metastases, which may go undetected on conventional radiologic imaging. ¹¹C-hydroxyephedrine binds to the norepinephrine transporter receptor and is detected by PET/CT (HED-PET/CT). It has previously demonstrated high accuracy in detecting primary and metastatic PPGL; however, its impact on preoperative staging is unclear. In this study, we retrospectively analyzed a selected cohort of 44 patients with large PPGL to evaluate whether HED-PET/CT influences preoperative clinical decision-making. All patients who underwent HED-PET/CT at Uppsala University Hospital between 2004 and 2024 were screened for inclusion. In total, 44 patients with pheochromocytomas >5 cm and paragangliomas >4 cm were included. HED-PET/CT results were compared with CT/MR findings, and a final consensus was reached on whether preoperative HED-PET/CT would have altered clinical decision-making. HED-PET/CT identified previously undetected metastatic disease in three patients (6.8%), which had not been visualized on CT/MR. Additionally, two patients had discordant findings, where HED-PET/CT revealed additional metastases. In one case, a liver metastasis was identified postoperatively with HED-PET/CT, leading to a metastasectomy that could have potentially been avoided. These findings suggest that HED-PET/CT is highly accurate in detecting metastases; however, its routine preoperative use may be limited and appears to provide significant clinical benefit only in selected patients.