General and comparative endocrinology最新文献

{"title":"Genetic analyses show frog metamorphosis requires thyroid hormone signaling increased by glucocorticoid receptor signaling.","authors":"Brett M Culbert, Mindy S Chen, Chamiska Hewa Uluwaduge, Lauren E Heininger, Hoang Anh Nguyen, Daniel R Buchholz","doi":"10.1016/j.ygcen.2026.114937","DOIUrl":"10.1016/j.ygcen.2026.114937","url":null,"abstract":"<p><p>Virtually all vertebrates experience a post-embryonic developmental transition dependent on thyroid and corticosteroid hormones. Molecular and developmental actions of these hormones are highly conserved among vertebrates, but the significance and nature of hormone interaction regulating the process has not been well understood. Frog metamorphosis is an excellent model for hormones in development due to the dramatic, sensitive, and readily manipulable changes occurring during the 2-week transition. In frogs, thyroid hormone initiates metamorphosis, and corticosteroid hormones accelerate thyroid hormone-induced changes. Sorting out precise roles of corticosteroid hormones and receptors has been challenging due to lack of genetic models. Here, we review results from four genetic frog models affecting corticosteroid signaling. Tadpoles with adrenocorticotropic hormone and glucocorticoid receptor mutations have low to no corticosteroid signaling and die during metamorphosis, but exogenous thyroid hormone allows them to complete metamorphosis. Tadpoles with 21-hydroxylase mutations survive through metamorphosis, despite lack of 21-hydroxyated corticosteroids, via corticosteroid signaling from high levels of low affinity steroid biosynthesis intermediates. Tadpoles with mineralocorticoid receptor mutations have no apparent metamorphic phenotype. These results indicate that survival through metamorphosis requires activation of the glucocorticoid receptor with no requirement for mineralocorticoid receptor activation. Further, these results show that the only vital role of corticosterone signaling through the glucocorticoid receptor is increasing tissue sensitivity to thyroid hormone thereby enabling endogenous thyroid hormone levels to accomplish metamorphic completion. These hormone interactions observed in frogs will inform similar examinations in other groups where developmental transitions may be highly influenced by such interactions but remain uncharacterized.</p>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":" ","pages":"114937"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147813620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoperiod effects on the expression of deep brain photoreceptors and gonadotrophin genes are sex- and age-dependent in Pekin ducks","authors":"E.M. Oluwagbenga,&nbsp;Nina Wilson,&nbsp;G.S. Fraley","doi":"10.1016/j.ygcen.2026.114928","DOIUrl":"10.1016/j.ygcen.2026.114928","url":null,"abstract":"<div><div>Birds rely on a specialized set of photoreceptive neurons called deep brain photoreceptors (DBPs) for the detection of light signals which are then integrated to modulate the expression of gonadotropin hormones. Therefore, we want to investigate DBPs expression, melanopsin (OPN 4), neuropsin (OPN5), and vertebrate ancient opsin (VAOpn), and their regulation of gonadotropin releasing hormone (GnRH) and gonadotropin inhibitory hormone (GnIH) genes in regards to sex and age in Pekin ducks. 460 hatchlings were randomly allocated to 4 rooms and exposed to 24 h light (LL) or photostimulation (PS; n = 30 hens and 7 drakes/pen; 4 pens/treatment) for 19 weeks. Ducks were euthanized via an intravenous injection of sodium pentobarbital (Fatal Plus; 396 mg/mL/kg body weight) at weeks 0, 5, 10, and 19 (n = 6/sex/treatment/timepoint) for brain sample collection which was further hemisected into diencephalon. Gene expressions of OPN 4, OPN5, and VAOpn, GnRH, and GnIH were quantified using qRT-PCR. In the hens, OPN4 expression was higher (p &lt; 0.05) in LL compared to PS at week 0, suggesting a rapid transcriptional response to continuous light but no difference in OPN5 expression. VAOpn expression was reduced (P &lt; 0.05) in PS compared to LL at week 10 in the hens. In parallel, GnRH expression was higher (p &lt; 0.05) under LL compared to PS at week 19, peaked at week 0 in both treatments and declined (p &lt; 0.05) thereafter in the hens. In contrast, GnIH expression increased (p &lt; 0.01) with age in both sexes, and was lower in the PS hens compared to LL hens at week 10. These findings demonstrate photoperiod-dependent variation in DBPs alongside GnRH and GnIH transcription which is consistent with a possible involvement in sex-specific reproductive development in ducks.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114928"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147652962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elucidating the regulatory mechanism of differentially expressed miRNA in the proliferation and differentiation of bovine intramuscular fat preadipocytes","authors":"Diba Dedacha Jilo ,&nbsp;Belete Kuraz Abebe ,&nbsp;Juntao Guo ,&nbsp;Jianfang Wang ,&nbsp;Haobin Ma ,&nbsp;Zhimei Yang ,&nbsp;Haibing Liu ,&nbsp;Gong Cheng ,&nbsp;Anning Li ,&nbsp;Linsen Zan","doi":"10.1016/j.ygcen.2026.114935","DOIUrl":"10.1016/j.ygcen.2026.114935","url":null,"abstract":"<div><div>Meat quality characteristics such as juiciness, tenderness, and flavor are greatly enhanced by intramuscular fat (IMF). Improving intramuscular adipose tissue accumulation while maintaining stable lipid levels in fat depots has become a critical priority in the beef sector. Understanding the molecular mechanisms driving intramuscular fat deposition is critical because it can enable the utilization of genetic selection to produce high-quality beef. Emerging research suggests that miRNAs play essential roles in regulating IMF deposition, particularly through regulating preadipocyte dynamics such as proliferation and differentiation. Our study aimed to screen and explore the function of potential miRNA in bovine intramuscular preadipocytes and to delineate the underlying molecular mechanisms governing cell proliferation and differentiation. Through time series cluster analysis following by experimental validation by qPCR and Agarose gel PCR identified that bta-miR-380-3p was potential miRNA that highly related with intramuscular preadipocyes differentiation in beef cattle. Bta-miR-380-3p enhanced the proliferation of intramuscular pre-adipocytes by increasing the cell cycle progression and show dynamic time dependent regulation during proliferation and differentiation. It also boosted the formation of lipid droplets in intramuscular pre-adipocytes. The qPCR results revealed that bta-miR-380-3p mimic boosted the expression of PPARγ, FASN, FABP4, SREBP1, and DGAT2 differentiation marker genes. These results provide new insight on the regulatory processes of intramuscular adipogenesis and identify bta-miR-380-3p as a potential target for increasing beef quality through directional selection and molecular breeding. This finding provides a theoretical framework and molecular targets for increasing IMF content.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114935"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147768964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discovery and pleiotropic effects of a “Feeding Circuit-Activating Peptide”-type neuropeptide in the mollusk Lymnaea stagnalis","authors":"Tomohiro Osugi ,&nbsp;Anna Szántó ,&nbsp;Réka Svigruha ,&nbsp;Tamara Lena Tacey ,&nbsp;Zsolt Bozsó ,&nbsp;Gábor K. Tóth ,&nbsp;Shin Matsubara ,&nbsp;Honoo Satake ,&nbsp;István Fodor ,&nbsp;Zsolt Pirger","doi":"10.1016/j.ygcen.2026.114925","DOIUrl":"10.1016/j.ygcen.2026.114925","url":null,"abstract":"<div><div>Neuropeptides play a central role in the regulation of animal physiology and behavior. Mollusks have been pivotal in the discovery of neuropeptide signaling, yet the diversity and functional roles of neuropeptides remain incompletely understood across the phylum. In this study, we identified and characterized a novel Feeding Circuit-Activating Peptide (FCAP)-type neuropeptide in the widely used molluscan model, the great pond snail (<em>Lymnaea stagnalis</em>). Using mass spectrometry imaging (MSI), we detected a new peptide, ALDLSGGFNVHGW, which differs by a single amino acid from FCAPb (ALDLSGGFQVHGW) of <em>Aplysia californica</em>. Sequence analysis revealed that the FCAP precursor of <em>L. stagnalis</em> contains 20 copies of ALDLSGGFNVHGW and one copy of an active peptide identical to Ap-FCAPb. Subsequent MSI analysis indicated that ALDSLGGFNVHGW is the main active FCAP-type peptide, predominantly localized in the anterior lobe of the right cerebral ganglion and sparsely in the buccal ganglia. Furthermore, ALDLSGGFNVHGW co-localized with APGWamide, but not with FMRFamide or cardioexcitatory peptide. Behavioral assays demonstrated dose-dependent, pleiotropic effects of ALDLSGGFNVHGW: transient suppression of feeding, delayed enhancement of locomotor activity, and robust stimulation of egg-laying. Together, these anatomical, molecular, and behavioral data support the view that peptides of the FCAP family are not restricted to feeding modulation but instead act as multifunctional regulators. Future studies, including identification of the receptor(s) that mediate the effects of FCAP-type peptides, are required to deepen our understanding of their functions and evolutionary relationships with neuropeptides in other phyla.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114925"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147638496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diurnal variation of plasma corticosterone, glucose, and protein levels in captive rice field frog Hoplobatrachus rugulosus (Wiegmann, 1834)","authors":"Artit Apibanpathomrat ,&nbsp;Wichase Khonsue ,&nbsp;Khattapan Jantawongsri ,&nbsp;Noppadon Kitana","doi":"10.1016/j.ygcen.2026.114933","DOIUrl":"10.1016/j.ygcen.2026.114933","url":null,"abstract":"<div><div>Corticosterone (CORT) is a major stress hormone in amphibians that shows rhythmic daily variation and plays a central role in metabolic regulation. Those responses can potentially be altered under captive conditions. This study aimed to investigate daily variations in plasma CORT, glucose, and total protein (TP) levels in captive <em>Hoplobatrachus rugulosus</em> during wet and dry seasons. Blood samples were collected every 4 h over a 24-h period from adult male and female frogs and analyzed, revealing sex-specific diurnal and seasonal patterns in these physiological parameters. In males, plasma CORT levels exhibited significant diurnal variation in both seasons, with lower levels at night compared to the afternoon, whereas females showed significant seasonal differences in CORT levels. Glucose levels differed between seasons in males, suggesting seasonal changes in metabolic demand, while females showed diurnal variation during the wet season, likely associated with feeding schedules. The TP levels varied seasonally in males, whereas females displayed diurnal variation during the dry season, indicating sex-specific strategies in energy allocation and physiological regulation under contrasting environmental conditions. These findings highlight seasonal and sex-specific physiological adjustments in captive <em>H. rugulosus</em>, providing insights that could improve frog rearing practices in Thailand.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114933"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147716541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hormonal actions of relaxin-like gonad-stimulating peptide in starfish","authors":"Masatoshi Mita","doi":"10.1016/j.ygcen.2026.114930","DOIUrl":"10.1016/j.ygcen.2026.114930","url":null,"abstract":"<div><div>Oocyte maturation is a process that occurs in the ovaries, where immature oocytes resume meiosis to attain competence for normal fertilization after ovulation/spawning. Gonadotropic hormone (GTH) is the initial trigger of this process. Relaxin-like gonad-stimulating peptide (RGP) in starfish is the first neuropeptide hormone with GTH-like activity identified in invertebrates. RGP is a heterodimeric peptide consisting of A- and B-chains, belonging to the insulin superfamily, particularly the relaxin group. This review describes the mechanism of action of RGP from oocyte maturation to ovulation in starfish. Recently, RGP has been found to be distributed in the nerve plexus around gonoducts connecting gonads and gonopores. This suggests that RGP secreted from the gonoducts stimulates ovarian follicle cells and testicular interstitial cells to produce the maturation-inducing hormone, 1-methyladenine (1-MeAde). RGP acts on receptors, G proteins, and adenylyl cyclase in these target cells, increasing intracellular cyclic AMP levels and resulting in 1-MeAde production. The RGP receptor is a rhodopsin-like G protein-coupled receptor which is homologous to human relaxin family peptide receptor and <em>Drosophila</em> leucine-rich repeat G protein-coupled receptor 3. Interestingly, the Gαs protein, which is important for RGP signal transduction, is absent from follicle cells surrounding the small oocytes before the breeding season, but is expressed during the breeding season. Neither RGP nor 1-MeAde is directly involved in the gonadal contraction required for ovulation. While some neuropeptides may be involved in gonadal contraction and relaxation, 1-MeAde likely induces the secretion of non-neuronal acetylcholine in the ovaries and testes, resulting in muscle contraction of the gonadal wall to release mature oocytes and sperm.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114930"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147662338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constitutive activation of MC1R in the large-billed crow (Corvus macrorhynchos) and its potential role in black plumage","authors":"Saya Nakano ,&nbsp;Yuichi Tashiro ,&nbsp;Hibiki Fukuchi ,&nbsp;Sayaka Aizawa ,&nbsp;Sakae Takeuchi","doi":"10.1016/j.ygcen.2026.114924","DOIUrl":"10.1016/j.ygcen.2026.114924","url":null,"abstract":"<div><div>Melanin-based plumage coloration in birds is largely regulated by the melanocortin 1 receptor (MC1R), a G protein–coupled receptor that promotes eumelanin synthesis via cAMP signaling. In domestic chickens, constitutively activating mutations such as the MC1R^E (E92K) allele cause melanistic phenotypes, demonstrating that persistent MC1R activation can drive generalized darkening. However, to our knowledge, no experimental study has directly demonstrated constitutive MC1R activation in wild birds exhibiting uniformly black plumage. We investigated the sequence and signaling properties of MC1R from the Large-billed Crow (<em>Corvus macrorhynchos</em>), a species with strongly eumelanin-dominant plumage. Crow MC1R exhibited elevated basal cAMP signaling and minimal responsiveness to α-melanocyte-stimulating hormone (α-MSH) in both stable Chinese hamster ovary (CHO-K1) cells and transient CRE-luciferase assays in HEK293T cells, demonstrating ligand-independent activation comparable to that observed in the melanizing chicken MC1R^E (E92K) allele. Comparative sequence analysis identified multiple substitutions conserved across <em>Corvus</em> species. Among these, E12K and E18K were functionally evaluated based on prior associations with melanism in other birds. Although E12K modestly increased basal signaling in chicken MC1R, E18K alone or in combination with E12K did not reproduce crow-level constitutive activity, and reciprocal substitutions in crow MC1R failed to abolish ligand-independent activation. These findings demonstrate that crow MC1R possesses constitutive activity and suggest that this phenotype reflects lineage-specific modifications rather than a single activating substitution. Our results provide experimental evidence that constitutive MC1R activation is a plausible molecular mechanism that may contribute to the black plumage in the Large-billed Crow, although a direct causal relationship remains to be established.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114924"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147620722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measuring diurnal and lifespan variations of Brain-derived neurotrophic factor in titi monkeys (Plecturocebus cupreus)","authors":"L.A. Meckler ,&nbsp;M.J. Sosnowski ,&nbsp;K.L. Bales","doi":"10.1016/j.ygcen.2026.114936","DOIUrl":"10.1016/j.ygcen.2026.114936","url":null,"abstract":"<div><div>Pair bonding requires substantial neural flexibility to form and maintain complex social relationships in dynamic environments over time. Due to its involvement in synaptic plasticity, Brain-derived neurotrophic factor (BDNF) is a promising candidate for modulating this flexibility, although it has never been studied within the context of pair bonding. The present study sought analytically and biologically validate an enzyme-linked immunosorbent assay (ELISA) to measure BDNF in coppery titi monkeys (<em>Plecturocebus cupreus</em>), a pair bonding non-human primate model. We first validated a commercially available ELISA to detect and measure BDNF in titi monkey serum, and then subsequently characterized the natural decline of BDNF in titi monkeys throughout the day (morning to evening) and across the lifespan (into old age). Titi monkeys showed significantly lower serum levels of BDNF at the end of the day, suggesting a consistent diurnal cycle, and in older age, suggesting age-related decline. This work establishes the foundation for examining BDNF’s role within the behavioral endocrinology of pair bonding.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"381 ","pages":"Article 114936"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147807943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PFOA effects on osteoblast differentiation: Involvement of oxidative stress and endocannabinoid receptors","authors":"Fiorenza Sella ,&nbsp;Christian Giommi ,&nbsp;Damiano Carbonari ,&nbsp;Marta Lombó ,&nbsp;Oliana Carnevali","doi":"10.1016/j.ygcen.2026.114932","DOIUrl":"10.1016/j.ygcen.2026.114932","url":null,"abstract":"<div><div>Perfluorooctanoic acid (PFOA), a persistent perfluoroalkyl substance (PFAS), has been implicated in bone mineral density loss and defective osteogenesis. In this study, by employing human fetal osteoblast (hFOB1.19), we investigated whether PFOA interferes with osteoblast differentiation by altering the transcription of genes involved in osteogenesis, and protein levels of oxidative stress defense and cannabinoid receptors (CBs). The hFOB 1.19 were exposed to increasing PFOA concentrations (1–100 µM) for seven days, representing supra-environmental concentration commonly used in mechanistic <em>in vitro</em> studies. Osteogenic markers were then evaluated at transcriptional level together with matrix deposition, and the results were compared to an untreated control group. Exposure to PFOA at 10 µM increased the expression of osteocalcin (<em>BGLAP</em>) encoding for a protein involved in calcium deposition. Catalase (CAT) protein levels were upregulated at 1 µM PFOA, while superoxide dismutase (SOD1) did not change, suggesting a selective antioxidant response to oxidative perturbation. Notably, this increase in CAT correlated with a trend toward <em>RUNX2</em> upregulation, possibly representing a compensatory mechanism to preserve differentiation under oxidative stress. In addition, the highest concentration of PFOA modulated the endocannabinoid system (ECS), reducing CB1 and CB2 protein levels. Despite these molecular changes, Alizarin Red staining revealed a borderline and not statistically significant enhanced calcium deposition only at 50 µM PFOA, suggesting potentially aberrant mineralization. Overall, our findings suggest that PFOA perturbs osteoblast differentiation through oxidative stress-linked mechanisms and CBs modulation, with catalase emerging as a key protective mediator of osteogenic competence under environmental contaminants. Furthermore, the observed dysregulation of CB1 and CB2 receptors indicates that the ECS itself may represent a direct target of PFOA action in osteoblasts.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114932"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147705499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Motilin in amphibians","authors":"Takio Kitazawa ,&nbsp;Hiroyuki Kaiya","doi":"10.1016/j.ygcen.2026.114917","DOIUrl":"10.1016/j.ygcen.2026.114917","url":null,"abstract":"<div><div>Motilin was first identified as a gastrointestinal (GI) motility-stimulating peptide and was later shown to mediate the gastric migrating motor complexes (MMCs) in several mammals. Motilin and its receptor have also been identified in non-mammalian vertebrates, including birds, reptiles, amphibians and fish. This discovery has prompted comparative studies on its physiological roles in GI motility. This review focused on amphibian motilin and its role in GI contractions. Like those of mammals, birds, and reptiles, amphibian motilin is a 22-amino-acid peptide produced in the mucosa of the upper small intestine. There is structural variation within amphibians: the N-terminal residue is phenylalanine in Caudata (newts and salamanders) but tyrosine in Apoda (caecilians). Interestingly, motilin receptors have been found in Anura (frogs), yet the endogenous motilin remains undiscovered, even though database searches. This discrepancy leaves the physiological role of the motilin system in anurans a subject of ongoing debate. Functional studies reveal that motilin receptors exist in the central nervous system and the GI tract of vertebrates, and demonstrate an evolutionarily related shift in localization. Motilin receptors are restricted to intestinal mucosal cells in fish but expand to GI smooth muscle cells and enteric neurons in amphibians. This marks a pivotal transition toward the regulation of GI motility. This trajectory culminates in birds and mammals, where receptors are present across the mucosa, smooth muscle, and myenteric plexus. However, the mechanisms driving this receptor expansion, the definitive status of motilin in Anuras, and the specific roles of motilin receptor or motilin-like receptor in these species remain unclear. Addressing these questions will provide deeper insights into the evolutionary endocrinology of the gut–brain axis, establishing amphibian motilin research as a compelling frontier.</div></div>","PeriodicalId":12582,"journal":{"name":"General and comparative endocrinology","volume":"380 ","pages":"Article 114917"},"PeriodicalIF":1.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147618612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}