Biology subjects

Iwakoshi-Ukena, E.

Publications and source records attributed to Iwakoshi-Ukena, E..

10 recordsLinked to original sources

bioRxiv2026

Hypothalamic neurosecretory protein GM causes fat deposition and suppresses gonadal maturation in Japanese quail

Introduction: Central regulation of energy homeostasis is essential for balancing lipid storage and reproductive investment; however, the hypothalamic factors governing this trade-off remain incompletely defined in birds. Neurosecretory protein GM (NPGM), an 83-amino acid hypothalamic factor, was investigated for its role in energy allocation during sexual maturation in Japanese quail (Coturnix japonica). Methods: Male and female quails at the onset of sexual maturation received chronic intracerebroventricular administration of NPGM for 13 days via osmotic pumps, during which their body mass, food intake, and water intake were monitored daily. At the endpoint, peripheral tissue and muscle masses, serum metabolite levels (glucose, fatty acids, triglycerides, testosterone, and 17{beta}-estradiol), hepatic triglyceride content, and gene expression profiles of hypothalamic feeding/reproductive genes and hepatic/adipose lipid metabolic genes were evaluated. Results: NPGM increased subcutaneous and abdominal fat in both sexes and was associated with suppressed gonadal maturation, as indicated by reduced testicular mass relative to body mass and lower testosterone levels in males, as well as a trend toward reduced ovarian mass and lower 17{beta}-estradiol levels in females. Sex-dependent metabolic phenotypes emerged: males exhibited increased body mass gain, hyperphagia, elevated water intake, enlarged liver, pancreas, and heart, higher serum and hepatic triglyceride levels, increased hepatic SCD1 expression, and reduced hepatic CGI-58, PPAR{gamma}, SLC2A2, and CD36. In contrast, females showed fat accumulation without hyperphagia or hepatic triglyceride elevation, accompanied by reduced hepatic VTG2 and APOV1 and decreased adipose ATGL, LPL, and FATP. Hypothalamic AGRP expression decreased in males, whereas both NPY and AGRP decreased in females. Discussion: These findings demonstrate that central NPGM shifts energy allocation from reproduction toward lipid storage through sex-dependent endocrine and metabolic mechanisms, identifying NPGM as a neuroendocrine regulator of energy allocation during sexual maturation in Japanese quails.

neuroscience↗

bioRxiv2026

Cold-induced hepatic metabolic change links gluconeogenesis, lipid remodeling, and redox regulation in Xenopus laevis

BackgroundEctothermic vertebrates exhibit substantial physiological plasticity in response to environmental temperature fluctuations. Among them, amphibians show particularly pronounced metabolic adjustments under cold conditions; however, the molecular mechanisms by which the liver adapts to low temperatures remain poorly understood. To address this gap, we investigated the hepatic transcriptional response to cold exposure in the African clawed frog (Xenopus laevis) using RNA sequencing (RNA-seq) and quantitative PCR. ResultsExposure to 5{degrees}C for five days in X. laevis resulted in pronounced hyperglycemia and extensive transcriptional reprogramming in the liver. RNA-seq analysis indicated that, relative to frogs maintained at 24{degrees}C, 2,392 genes were upregulated, whereas 2,031 genes were downregulated. Notably, genes associated with gluconeogenesis, such as foxo1, g6pc1, and pck1, exhibited significant upregulation, whereas genes related to glycolysis and glucose utilization, including gck, pfkm, and ldhb, were downregulated. Concurrently, cold exposure induced the expression of genes involved in fatty acid synthesis, desaturation, and cholesterol biosynthesis, such as srebf1, acaca, fasn, scd, fads2, srebf2, and hmgcr. Conversely, genes related to fatty acid {beta}-oxidation, including ppara, cpt1a, cpt1b, slc25a20, acadl, hadha, and hadhb, were significantly suppressed. In alignment with this pattern, multiple components of the mitochondrial electron transport chain and ATP synthesis machinery were also downregulated. Additionally, gene groups involved in antioxidant defenses, such as gpx4, gpx1, prdx2, prdx5, prdx6, and ferritin-related genes, were upregulated. Representative transcriptomic changes were validated using quantitative PCR analysis. ConclusionsExposure to cold temperatures induced coordinated metabolic reprogramming in the liver of X. laevis. This reprogramming was characterized by the activation of gluconeogenesis, suppression of glycolysis, fatty acid {beta}-oxidation, and oxidative phosphorylation, and induction of lipid and cholesterol biosynthetic pathways. These metabolic adjustments suggest that frogs acclimated to cold conditions adopt an energy-conserving metabolic strategy while sustaining glucose production and promoting lipid remodeling to adapt to low-temperature environments. These findings offer novel insights into the molecular mechanisms underlying cold adaptation in ectothermic vertebrates and underscore the pivotal role of the liver in managing transcriptional responses to cold stress.

physiology↗

bioRxiv2025

Ion transport peptide regulates body water balance via a receptor guanylyl cyclase in the Drosophila hindgut

Maintaining internal water balance, including ionic and osmotic balance, is critical for animal development and survival. In insects, internal water balance is regulated through the Malpighian tubules and the hindgut, which transport water and ions across their epithelia under the regulation of multiple peptide hormones. One of these, ion transport peptide (ITP), a member of the highly conserved crustacean hyperglycemic hormone superfamily among ecdysozoans, is an anti-diuretic hormone in insects, but its mechanism of action remains largely unclear. Here, we show that the short amidated isoform of ITP (saITP), secreted from brain neurosecretory cells, regulates water absorption via the receptor guanylyl cyclase (rGC) Gyc76C in the hindgut of the fruit fly Drosophila melanogaster. Both ITP and Gyc76C are evolutionarily conserved and are essential for larval survival in D. melanogaster, as mutation or knockdown of either gene results in early larval lethality. In Drosophila S2 cells, synthetic saITP increases intracellular cyclic GMP (cGMP) in a Gyc76C-dependent manner, an effect abolished by deletion of its putative ligand-binding domain. Using the fluorescent cGMP biosensor RedcGull in ex vivo-cultured hindguts, we found that saITP increases epithelial cGMP levels, and this response requires Gyc76C. Consistently, saITP promotes hindgut water reabsorption via Gyc76C. Thus, saITP acts via Gyc76C in a brain-hindgut neuroendocrine axis that regulates internal water balance during development. Our study provides new insight into the neuroendocrine control of osmoregulation in ecdysozoans and supports a broader role for rGCs in peptide-hormone signaling.

physiology↗

bioRxiv2025

Neurosecretory protein GL stimulates feeding behavior and fat accumulation in Japanese quails (Coturnix japonica)

Neurosecretory protein GL (NPGL) is a novel hypothalamic neuropeptide that promotes fat accumulation in rats, mice, and neonatal chicks. However, its role in Japanese quails (Coturnix japonica) remains unclear. In this study, we investigated the effects of chronic intracerebroventricular infusion of NPGL on body mass, food intake, and fat accumulation in five-week-old male Japanese quails. A 13-day administration of NPGL significantly increased body mass, food intake, and the masses of subcutaneous fat, abdominal fat, and liver. In contrast, water intake and the masses of the pancreas, testes, heart, and muscle remained unchanged. Blood concentrations of triglyceride, glucose, and non-esterified fatty acid were unaffected. Real-time qPCR analysis revealed a significant upregulation of NPGM, a paralogous gene of NPGL, in the hypothalamus. Additionally, the expression of stearoyl-CoA desaturase 1 (SCD1), a key enzyme in lipogenesis, showed an increasing trend in the liver. Although the fatty acid ratio did not change in the SCD1 activity index (palmitoleate/palmitate), the de novo lipogenesis index (palmitate/linoleate) exhibited an upward trend in both the liver and abdominal fat. These results suggest that NPGL promotes fat accumulation in Japanese quails, highlighting its potential role as a contributing factor to obesity in avian species.

zoology↗

bioRxiv2023

Expression of mRNAs Encoding Hypothalamic Small Proteins, Neurosecretory Protein GL and Neurosecretory Protein GM, in the Japanese Quail, Coturnix japonica

Neurosecretory protein GL (NPGL) and neurosecretory protein GM (NPGM) are novel neuropeptides that have been discovered in the hypothalamic infundibulum of chickens. NPGL and NPGM play important roles in lipid metabolism in juvenile chickens. The physiological functions of NPGL and NPGM in sexually mature birds remain unknown. The Japanese quail (Coturnix japonica) seems to be an appropriate model for analyzing NPGL and NPGM during sexual maturity. However, studies on NPGL or NPGM have yet to be reported in the Japanese quail. In the present study, we identified cDNAs encoding precursor proteins of NPGL and NPGM in the quail hypothalamus. In situ hybridization revealed that NPGL mRNA-expressing cells in the hypothalamus were localized in the infundibular nucleus and median eminence, and NPGM mRNA-expressing cells were only found in the mammillary nucleus. Immunohistochemistry revealed that NPGM-like immunoreactive cells were distributed in the mammillary nucleus, whereas NPGL-like immunoreactive cells were not detected in the hypothalamus. Real-time PCR analysis indicated that the expression of NPGL mRNA was higher in the hypothalamus of females than in males, and NPGM mRNA expression showed no sex differences. NPGL and NPGM mRNA expression in males was upregulated after 24 h of food deprivation. In females, only NPGM mRNA expression was increased by fasting. These results suggest that the physiological functions of NPGL and NPGM are different in quail, and these factors are involved in sex differences in energy metabolism.

zoology↗

bioRxiv2021

Neurosecretory protein GL-induced fat accumulation is accompanied by repressing the immune-inflammatory response in the adipose tissue of mice

We have recently identified neurosecretory protein GL (NPGL), a small secretory protein expressed in the vertebrate hypothalamus, as an orexigenic factor with remarkable fat accumulation by overexpression of the NPGL precursor gene (Npgl) for two months. In the present study, we analyzed the effects of short-term Npgl overexpression for 18 days as the early stage of obesity to address the mechanisms underlying obese-like phenotype. Similar to previous studies, short-term Npgl overexpression stimulated food intake and fat accumulation in the white adipose tissues (WAT), whereas the masses of the brown adipose tissue, testis, liver, heart, and muscle remained unchanged. In addition, we observed increased blood insulin and leptin levels due to Npgl overexpression, while little changes were induced in blood glucose, free fatty acids, triglyceride, and cholesterol levels. Furthermore, transcriptome analysis of the inguinal WAT using RNA-sequencing technique revealed that overexpression of Npgl upregulated the genes involved in cytoskeleton regulation, whereas it decreased those involved in immune-inflammatory responses. These results suggest that NPGL plays a crucial role in enlarging adipocytes and suppressing inflammation to avoid metabolic abnormalities, eventually contributing to accelerating energy storage.

physiology↗

bioRxiv2021

A Novel Hypothalamic Factor, Neurosecretory Protein GM, Causes Fat Deposition in Chicks

We recently discovered a novel cDNA encoding the precursor of a small secretory protein, neurosecretory protein GM (NPGM), in the mediobasal hypothalamus of chickens. Although our previous study showed that subcutaneous infusion of NPGM for 6 days increased body mass in chicks, the chronic effect of intracerebroventricular (i.c.v.) infusion of NPGM remains unknown. In this study, chronic i.c.v. infusion of NPGM for 2 weeks significantly increased body mass, water intake, and the mass of abdominal fat in chicks, whereas NPGM did not affect food intake, muscle mass, or blood glucose concentration. Morphological analyses revealed that fat accumulation occurred in both liver and abdominal fat. These results indicate that NPGM may participate in fat storage in chicks.

physiology↗

bioRxiv2021

Overexpression of the gene encoding neurosecretory protein GL precursor prevents excessive fat accumulation in the adipose tissue of mice fed a long-term high-fat diet

We previously identified a novel small hypothalamic protein, neurosecretory protein GL (NPGL), which induces feeding behavior and fat accumulation in rodents depending on their diet. In the present study, we explored the effects of NPGL on feeding behavior and energy metabolism in mice placed on a long-term high-fat diet with 60% calories from fat (HFD 60). Overexpression of the NPGL precursor gene (Npgl) over 18 weeks increased food intake and body mass. The weekly body mass gain of Npgl-overexpressing mice was higher than that of controls until 7 weeks from induction of overexpression, after which it ceased to be so. Oral glucose tolerance tests showed that Npgl overexpression maintained glucose tolerance and increased blood insulin levels, and intraperitoneal insulin tolerance tests showed that it maintained insulin sensitivity. At the experimental endpoint, Npgl overexpression was associated with increased mass of the perirenal white adipose tissue (WAT) and decreased mass of the epididymal WAT (eWAT), resulting in little effect on the total WAT mass. These results suggest that under long-term HFD 60 feeding, Npgl overexpression may play a role in avoiding metabolic disturbance both by accelerating energy storage and by suppressing excess fat accumulation in certain tissues, such as the eWAT.

physiology↗

bioRxiv2021

Subcutaneous infusion of neurosecretory protein GL promotes fat accumulation in mice

We recently identified a novel small secretory protein, neurosecretory protein GL (NPGL), in the vertebrate hypothalamus. We revealed that NPGL is involved in energy homeostasis using intracerebroventricular infusion in rodents. However, the effect of NPGL through peripheral administration remains to be elucidated and may be important for therapeutic use. In this study, we performed subcutaneous infusion of NPGL in mice for 12 days and found that it accelerated fat accumulation in white adipose tissue (WAT) without increasing in body mass gain and food intake. The mass of the testis, liver, kidney, heart, and gastrocnemius muscle remained unchanged. Analysis of mRNA expression by quantitative reverse transcription-polymerase chain reaction showed that proopiomelanocortin was suppressed in the hypothalamus by the infusion of NPGL. We observed a decreasing tendency in serum triglyceride levels due to NPGL, while serum glucose, insulin, leptin, and free fatty acids levels were unchanged. These results suggest that the peripheral administration of NPGL induces fat accumulation in WAT via the hypothalamus.

physiology↗

bioRxiv2021

Hypothalamic Overexpression of Neurosecretory Protein GL Leads to Obesity in Mice

IntroductionThe mechanisms underlying obesity are not fully understood, necessitating the creation of novel animal models for investigation of metabolic disorders from the cellular-molecular to behavioral levels of analysis. We have previously found that neurosecretory protein GL (NPGL), a newly-identified hypothalamic neuropeptide, is involved in feeding behavior and fat accumulation in rats. Given the broad availability of genetic tools in mice, the present investigation sought to establish a mouse model of NPGL-induced obesity. MethodsWe overexpressed the NPGL-precursor gene (Npgl) in the hypothalamus using adeno-associated virus in C57BL/6J mice fed normal chow (NC) or a high-calorie diet (HCD). After 9 weeks of Npgl overexpression, we measured adipose tissues, muscle, and several organ masses in addition to food intake and body mass. To assess the effects of Npgl overexpression on peripheral tissues, we analyzed mRNA expression of lipid metabolism-related genes by quantitative RT-PCR. ResultsNpgl overexpression increased food intake, body mass, adipose tissues and liver masses, food efficiency, and circulating insulin levels under both NC and HCD, resulting in obesity observable within 8 weeks. Furthermore, we observed fat accumulation in adipose tissues and liver. Additionally, mRNA expression of lipid metabolism-related factors was increased in white adipose tissue and the liver after Npgl overexpression. ConclusionTaken together, the present study suggests that NPGL is an endogenous obesogenic factor that acts within a short period of time in mice. As a result, this animal model can be widely applied to study the etiology of obesity from genes to behavior.

neuroscience↗