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β-Catenin is a bifunctional molecule that is an effector of the wingless-related integration site (Wnt) signaling to control gene expression and contributes to the regulation of cytoskeleton and neurotransmitter vesicle trafficking. In its former role, β-catenin binds transcription factor 7-like 2 (TCF7L2), which shows strong genetic associations with the pathogenesis of obesity and type-2 diabetes. Here, we sought to determine whether β-catenin plays a role in the neuroendocrine regulation of body weight and glucose homeostasis. Bilateral injections of adeno-associated virus type-2 (AAV2)-mCherry-Cre were placed into the arcuate nucleus of adult male and female β-catenin flox mice, to specifically delete β-catenin expression in the mediobasal hypothalamus (MBH-β-cat KO). Metabolic parameters were then monitored under conditions of low-fat (LFD) and high-fat diet (HFD). On LFD, MBH-β-cat KO mice showed minimal metabolic disturbances, but on HFD, despite having only a small difference in weekly caloric intake, the MBH-β-cat KO mice were significantly heavier than the control mice in both sexes ( p  < 0.05). This deficit seemed to be due to a failure to show an adaptive increase in energy expenditure seen in controls, which served to offset the increased calories by HFD. Both male and female MBH-β-cat KO mice were highly glucose intolerant when on HFD and displayed a significant reduction in both leptin and insulin sensitivity compared with controls. This study highlights a critical role for β-catenin in the hypothalamic circuits regulating body weight and glucose homeostasis and reveals potential mechanisms by which genetic variation in this pathway could impact on development of metabolic disease., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 the authors.)

Objective: This retrospective (matched paired) clinical trial aimed to compare the efficacy of dexamethasone vs. methylprednisolone at equipotent (high) doses in patients with coronavirus disease 2019 (COVID-19)-associated acute respiratory distress syndrome (ARDS)., Methods: A total of 347 patients with moderate and severe COVID-19-associated ARDS were administered either a high (equipotent) dose of dexamethasone (32 mg) or methylprednisolone (180 mg) for a duration of up to 10 days. All participants received the standard of care for critically ill COVID-19 patients., Results: The primary outcomes included length of stay in the ICU, ICU mortality, and discharge from the hospital.   Based on the obtained results, a tendency towards more favorable clinical outcomes concerning the length of stay in the ICU (in the group of patients treated with non-invasive mechanical ventilation (NIV), p<0.05), ICU mortality, and discharge from the hospital (in the group of patients who were intubated, p<0.05) in patients receiving the high dose of dexamethasone compared to those receiving methylprednisolone was observed., Conclusion: It appears that severe cases of COVID-19, especially intubated ones, treated with high doses of dexamethasone have a more favorable clinical outcome than the use of equipotent doses of methylprednisolone. However, larger multicenter studies are needed to validate our observations., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Kovacevic et al.)

Background Opioid-induced constipation (OIC) has become more common in the intensive care unit (ICU) due to increased opioid utilization. Traditional laxatives often prove ineffective against OIC, leading to the increased utilization of naloxegol. However, further research is needed to confirm naloxegol's effectiveness and safety in critical care. This study aimed to explore the safety and efficacy of this intervention in critically ill OIC patients. Methods A single-center retrospective study was conducted on 353 patients who received one or more doses of naloxegol from January 1, 2019, to June 30, 2020, for OIC at a tertiary care center. The primary endpoint of this study was to evaluate serious adverse events such as reduced analgesic effect, gastrointestinal perforation, seizure, acute myocardial infarction (AMI), or ventricular arrhythmias using Naranjo Scale in critically ill patients. The secondary goal was to assess the efficacy of naloxegol, measured by the time of the first bowel movement. Results The average duration of naloxegol use was three days, with the first bowel movement occurring at an average of 11.3 hours. Furthermore, 59.8% of individuals had their first bowel movement within 20 hours of receiving naloxegol. There was a low level of causality between naloxegol use and adverse events such as gastrointestinal perforation, seizures, AMI, cardiovascular mortality, stroke, and ventricular arrhythmia. Additionally, reduction in analgesia showed no strong relationship with naloxegol use indicated by the Naranjo Scale assessment. Conclusion Naloxegol showed promising safety and efficacy profiles in treating OIC amongst critically ill patients, though our findings require further validation through prospective studies. This research paves the way for further investigation into naloxegol's role in OIC management, emphasizing the necessity of personalized treatment strategies in critical care settings., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Rizwan et al.)

To induce diet-induced obesity (DIO) in rodents, diets high in saturated fat and/or carbohydrates are commonly used. In the laboratory, standardised diets evolved over time without paying particular attention to the effect of fat composition on metabolic alterations. In the present study, customised high-fat diets (HFD) enriched with a combination of lard and different concentrations of New Zealand green-lipped mussel (Perna canaliculus) oil or MSC Hoki (Macruronus novaezelandiae, blue grenadier) liver oil, important sources of n-3 PUFA, in comparison with a solely lard-based diet, were fed to lean and DIO male C57BL/6 mice and their effects on metabolic parameters were monitored. Intriguingly, an isoenergetic HFD containing 63 % of total fat in the form of mussel oil and only 28 % in the form of lard attenuated HFD-induced body weight gain after 1 and 4 weeks, respectively. Consistently, changing a lard-enriched HFD to the mussel oil diet reduced body weight markedly even after mice had been exposed to the former diet for 10 months. The weight-reducing effect of the diet was not caused by altered energy intake or expenditure, but was associated with reduced visceral fat mass. Collectively, these data suggest a novel weight-reducing potential of green-lipped mussel oil.

RF-amide related peptide 3 (RFRP-3) is a neuropeptide thought to inhibit central regulation of fertility. We investigated whether alterations in RFRP neuronal activity led to changes in puberty onset, fertility, and stress responses, including stress and glucocorticoid-induced suppression of pulsatile luteinizing hormone secretion. We first validated a novel RFRP-Cre mouse line, which we then used in combination with Cre-dependent neuronal ablation and DREADD technology to selectively ablate, stimulate, and inhibit RFRP neurons to interrogate their physiological roles in the regulation of fertility and stress responses. Chronic RFRP neuronal activation delayed male puberty onset and female reproductive cycle progression, but RFRP-activated and ablated mice exhibited apparently normal fertility. When subjected to either restraint- or glucocorticoid-induced stress paradigms. However, we observed a critical sex-specific role for RFRP neurons in mediating acute and chronic stress-induced reproductive suppression. Female mice exhibiting RFRP neuron ablation or silencing did not exhibit the stress-induced suppression in pulsatile luteinizing hormone secretion observed in control mice. Furthermore, RFRP neuronal activation markedly stimulated glucocorticoid secretion, demonstrating a feedback loop whereby stressful stimuli activate RFRP neurons, which in turn further activate the stress axis. These data provide evidence for a neuronal link between the stress and reproductive axes., Competing Interests: The authors declare no competing financial interests., (Copyright © 2021 the authors.)

Recent evidence suggests that the circadian timing system plays a role in energy and glucose homeostasis, and disruptions to this system are a risk factor for the development of metabolic disorders. We exposed animals to a constantly shifting lighting environment comprised of a 6-hour advance, occurring every 6 days, to chronically disrupt their circadian timing system. This treatment caused a gradual increase in body weight of 12 ± 2% after 12 phase shifts, compared with a 6 ± 1% increase in mice under control lighting conditions. Additionally, after the fifth phase shift, light cycle-disrupted (CD) animals showed a reversal in their diurnal pattern of energy homeostasis and locomotor activity, followed by a subsequent loss of this rhythm. To investigate potential molecular mechanisms mediating these metabolic alterations, we assessed central leptin and insulin sensitivity. We discovered that CD mice had a decrease in central leptin signaling, as indicated by a reduction in the number of phosphorylated signal transducer and activator of transcription 3 immunoreactive cells in the arcuate nucleus of the hypothalamus. Furthermore, CD animals exhibited a marked increase in fasting blood glucose (269.4 ± 21.1 mg/dL) compared with controls (108.8 ± 21.3 mg/dL). This dramatic increase in fasting glucose levels was not associated with an increase in insulin levels, suggesting impairments in pancreatic insulin release. Peripheral hyperglycemia was accompanied by central alterations in insulin signaling at the level of phospho Akt and insulin receptor substrate 1, suggesting that light cycle disruption alters central insulin signaling. These results provide mechanistic insights into the association between light cycle disruption and metabolic disease., (Copyright © 2019 Endocrine Society.)

Estradiol and leptin are critical hormones in the regulation of body weight. The aim of this study was to determine whether this cross talk between leptin receptor (LepRb) and estrogen receptor-α (ERα) signaling is critical for estradiol's anorexigenic effects. Leprb-Cre mice were crossed with Cre-dependent Tau-green fluorescent protein (GFP) reporter, Stat3-flox or Erα-flox mice to generate female mice with GFP expression, signal transducer and activator of transcription 3 (STAT3) knockout (KO), or ERα KO, specifically in LepRb-expressing cells. The proportion of Leprb-GFP cells colocalizing ERα was high (∼80%) in the preoptic area but low (∼10%) in the mediobasal hypothalamus, suggesting that intracellular cross talk between these receptors is minimal for metabolic regulation. To test whether estradiol enhanced arcuate leptin sensitivity, ovarectomized mice received varying levels of estradiol replacement. Increasing estrogenic states did not increase the degree of leptin-induced STAT3 phosphorylation. LepRb-specific STAT3 KO mice and controls were ovarectomized and given either chronic estradiol or vehicle treatment to test whether STAT3 is required for estrogen-induced body weight suppression. Both groups of estradiol-treated mice showed an equivalent reduction in body weight and fat content compared with vehicle controls. Finally, mice lacking ERα specifically in LepRb-expressing neurons also showed no increase in body weight or impairments in metabolic function compared with controls, indicating that estradiol acts independently of leptin-responsive cells to regulate body weight. However, fecundity was impaired in in Leprb-ERα KO females. Contrary to the current dogma, we report that estradiol has minimal direct actions on LepRb cells in the mediodasal hypothalamus and that its anorexigenic effects can occur entirely independently of LepRb-STAT3 signaling in female mice.

Insulin signaling in the brain plays an important role in the central regulation of energy homeostasis and fertility, such that mice exhibiting brain-specific deletion of insulin receptors (InsRs) display a diet-sensitive obesogenic phenotype and hypothalamic hypogonadism. However, the specific neurons mediating insulin's central effects on fertility remain largely unidentified. The neurotransmitters γ-aminobutyric acid (GABA) and glutamate are important modulators of fertility and energy homeostasis and are widely distributed in the hypothalamus. We therefore investigated whether insulin signaling via GABAergic or glutamatergic neurons plays an important role in the metabolic regulation of fertility. We used the Cre-loxP system to generate mice with a selective inactivation of the Insr gene from GABAergic (Vgat(+)) or glutamatergic (Vglut2(+)) cells by crossing Insr-flox mice with Vgat-Cre or Vglut2-Cre mice, respectively. Multiple reproductive and metabolic parameters were then compared between male and female Insr-flox/Vgat-Cre(+) (VgatIRKO), Insr-flox/Vglut2-Cre(+) (VglutIRKO), and Insr-flox/Cre-negative control (CON) mice. Female VgatIRKO mice exhibited a significant increase in adult body weight, abdominal fat mass, and fasting plasma insulin and leptin concentrations, but normal fasting glucose concentration and glucose tolerance compared with CON mice. Surprisingly, VgatIRKO and VglutIRKO mice exhibited normal reproductive maturation and function compared with CONs. No differences in the age of puberty onset, estrous cyclicity, or fertility were observed between VgatIRKO, VglutIRKO, and CON mice. However, male VgatIRKO mice exhibited significantly augmented LH concentration and a trend toward reduced seminal vesicle weight compared with CON mice, which may be indicative of primary hypogonadism. Our results therefore demonstrate that insulin signaling via GABAergic and glutamatergic cells is not required for fertility in mice, but show that GABAergic neurons encompass circuitry through which insulin acts to modulate energy homeostasis.

RFamide-related peptide-3 (RFRP-3) is known to inhibit the activity of GnRH neurons. It is not yet clear whether its G protein-coupled receptors, GPR147 and GPR74, are present on GnRH neurons or on afferent inputs of the GnRH neuronal network or whether RFRP-3 can inhibit gonadotropin secretion independently of GnRH. We tested the following: 1) whether GnRH is essential for the effects of RFRP-3 on LH secretion; 2) whether RFRP-3 neurons project to GnRH and rostral periventricular kisspeptin neurons in mice, and 3) whether Gpr147 and Gpr74 are expressed by these neurons. Intravenous treatment with the GPR147 antagonist RF9 increased plasma LH concentration in castrated male rats but was unable to do so in the presence of the GnRH antagonist cetrorelix. Dual-label immunohistochemistry revealed that approximately 26% of GnRH neurons from male and diestrous female mice were apposed by RFRP-3 fibers, and 19% of kisspeptin neurons from proestrous female mice were apposed by RFRP-3 fibers. Using immunomagnetic purification of GnRH and kisspeptin cells, single-cell nested RT-PCR, and in situ hybridization, we showed that 33% of GnRH neurons and 9-16% of rostral periventricular kisspeptin neurons expressed Gpr147, whereas Gpr74 was not expressed in either population. These data reveal that RFRP-3 can act at two levels of the GnRH neuronal network (i.e. the GnRH neurons and the rostral periventricular kisspeptin neurons) to modulate reproduction but is unable to inhibit gonadotropin secretion independently of GnRH.

Hypothalamic RFamide-related peptide-3 (RFRP-3) neurons inhibit LH secretion via a central action. A direct hypophysiotropic action on the gonadotropes has also been suggested. To assess central RFRP-3 effects on the GnRH/LH surge that induces ovulation, ovariectomized rats were subjected to an estradiol plus progesterone surge-induction protocol. Chronic infusion of RFRP-3 (2.5 or 25 ng/h, intracerebroventricularly) caused a dose-dependent 50-60% inhibition of GnRH neuronal activation (assessed by colocalization with the immediate early gene c-Fos) at the surge peak compared with vehicle-treated controls. RFRP-3 also suppressed neuronal activation in the anteroventral periventricular region, which provides stimulatory input to GnRH neurons, by 50-80% compared with control values. To test whether centrally administered RFRP-3 inhibits pulsatile GnRH/LH secretion, chronically ovariectomized, low-level estradiol-treated rats without surge induction were blood sampled every 10 min for 4 h. Bolus injection of RFRP-3 (0, 2.5, or 25 microg, intracerebroventricularly) after 1.5 h did not affect subsequent LH pulse frequency, pulse amplitude, or the mean concentrations of LH or prolactin. RFRP-3 treatment of isolated anterior pituitary cells at moderate doses of up to 10(-7) m did not significantly inhibit LH release, either with or without GnRH cotreatment. These data reveal a central inhibitory effect of RFRP-3 on the hypothalamo-pituitary gonadal axis specifically during the estradiol-induced GnRH/LH surge. This effect may include actions of RFRP-3 on GnRH neurons and/or their anteroventral periventricular afferent inputs but is unlikely to involve direct inhibition of LH secretion at the level of the gonadotrope.

An RFamide peptide named gonadotropin-inhibitory hormone, which directly inhibits gonadotropin synthesis and secretion from the anterior pituitary gland, has recently been discovered in the avian hypothalamus. It is not known whether the mammalian orthologs of gonadotropin-inhibitory hormone and RFamide-related peptide (RFRP)-1 and -3 act in the same way. We used a newly generated antibody against the rat RFRP precursor combined with retrograde tract tracing to characterize the cell body distribution and fiber projections of RFRP-1 and -3 neurons in rats. RFRP-1/3-immunoreactive cell bodies were found exclusively within the dorsomedial hypothalamus. Immunoreactive fibers were observed in the septal-preoptic area, hypothalamus, midbrain, brainstem, and hippocampus but not in the external zone of the median eminence. Intraperitoneal injection of the retrograde tracer Fluoro-Gold in rats resulted in the labeling of the majority of GnRH neurons but essentially no RFRP-1/3 neurons. In contrast, intracerebral injections of Fluoro-Gold into the rostral preoptic area and CA2/CA3 hippocampus resulted in the labeling of 75 +/- 5% and 21 +/- 8% of RFRP-1/3 cell bodies, respectively. To assess actions at the pituitary in vivo, RFRP-3 was administered as an iv bolus to ovariectomized rats and plasma LH concentration measured at 0, 2.5, 5, 10, and 30 min. RFRP-3 had no effects on basal secretion, but GnRH-stimulated LH release was reduced by about 25% at 5 min. Together these observations suggest that RFRP-3 is not a hypophysiotropic neuroendocrine hormone in rats.