General and Comparative Endocrinology

The pituitary gland is a small endocrine gland located below the hypothalamus. This gland releases several important hormones and controls the function of many other endocrine system glands to release hormones. Fish pituitary hormonal cells are controlled by neuroendocrine and sex steroid feedback. To study the complex pituitary function in vivo, we established an in vitro pituitary spheroid assay and evaluated its suitability for monitoring the annual reproductive physiological conditions in Takifugu rubripes, also known as torafugu, is one of the most economically important species distributed in the northwestern part of the Pacific Ocean, in the western part of the East China Sea, and in more northern areas near Hokkaido, Japan...

Neuropeptide Y is known to be directly or indirectly involved in immune regulation. The immune effects of NPY include immune cell transport, helper T cell differentiation, cytokine secretion, staining and killer cell activity, phagocytosis and production of reactive oxygen species. In this study, we investigated the immunoprotective effect of synthetic NPY on largemouth bass larvae. For the first time, the dose and time effects of NPY injection on largemouth bass was explored, and then Poly I:C and LPS infection was carried out in juvenile largemouth bass, respectively, after the injection of NPY...

Gonadotropin-inhibitory hormone (GnIH) was the first reported hypothalamic neuropeptide inhibiting reproduction in vertebrates. Since its discovery in the quail brain, its orthologs have been identified in a variety of vertebrate species and even protochordates. Depending on the species, the GnIH precursor polypeptides comprise two, three or four mature peptides of the RFamide family. It has been well documented that GnIH inhibits reproduction at the brain-pituitary-gonadal levels and participates in metabolism, stress response, and social behaviors in birds and mammals...

Several metabolic hormones signal an organism's energy balance to the brain and modulate feeding behaviours accordingly. These metabolic signals may also regulate other behaviour related to energy balance, such as food caching or hoarding. Ghrelin is one such hormone, but it appears to exert different effects on appetite and fat levels in birds and mammals. Ghrelin treatment inhibits food intake and decreases fat stores in some bird species, but these effects may differ between acylated and unacylated (des-acyl) forms of ghrelin...

Several internal and external factors can influence animals' hormonal activity. Cortisol level in hair and wool determines chronic stress, which is connected with the long-term HPA axis effect. Wool cortisol levels in alpacas have never been determined to this time. The study aimed to assess the influence of selected factors on wool cortisol concentration in alpacas. The study included 36 alpacas. Wool samples were collected during shearing in June 2021, cut with an electric clipper from the right shoulder and the rump...

Although well established that several fishes including goldfish in the suborder Cypinoidei within the family Cypriniformes use the maturation-inducing steroid 17,20β-dihydroxy-pregn-4-ene-3-one (17,20βP) and its metabolites as a priming pheromone which they detect with sensitivity and specificity, it is unclear whether and how other Cypriniformes might have evolved to do so. This study examined this question in the family Xenocyprididae. Using electro-olfactogram recording we tested the olfactory sensitivity of silver (Hypophthalmichthys molitrix) and bighead carp (H...

Heart development is a delicate and complex process regulated by coordination of various signaling pathways. In this study, we investigated the role of sox18 in heart development by modulating Wnt/β-Catenin signaling pathways. Our spatiotemporal expression analysis revealed that sox18 is mainly expressed in the heart, branchial arch, pharyngeal arch, spinal cord, and intersegmental vessels at the tailbud stage of Xenopus tropicalis embryo. Overexpression of sox18 in the X. tropicalis embryos causes heart edema, while loss-of-function of sox18 can change the signal of developmental heart marker gata4 at different stages, suggesting that sox18 plays an essential role in the development of the heart...

Tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE) is the major TBBPA derivative. It has been detected in different environmental samples. Previous studies show that TBBPA-DHEE caused neurotoxicity in rats. In this study, juvenile zebrafish were exposed to various concentrations of TBBPA-DHEE to ascertain the potential neurotoxicity of TBBPA-DHEE, the chemical, and its possible molecular mechanism of action. Behavioral analysis revealed that TBBPA-DHEE could significantly increase the swimming distance and speed in the 1...

Chondrichthyans have a novel proglucagon-derived peptide, glucagon-like peptide (GLP)-3, in addition to GLP-1 and GLP-2 that occur in other vertebrates. Given that the GLPs are important regulators of metabolic homeostasis across vertebrates, we sought to investigate whether GLP-3 displays functional actions on metabolism within a representative chondrichthyan, the Pacific spiny dogfish Squalus suckleyi. There were no observed effects of GLP-3 perfusion (10 nM for 15 min) on the rate of glucose or oleic acid acquisition at the level of the spiral valve nor were there any measured effects on intermediary metabolism within this tissue...

Most environments exhibit predictable yearly changes, permitting animals to anticipate them. The hypothalamic-pituitary-adrenal (HPA) axis is a key physiological pathway that enables animals to cope with such changes. Monitoring glucocorticoid (the end products of the HPA axis) levels in wild animals throughout the year can improve our understanding of how this pathway responds to different conditions. For this study, we collected 18 months of data on two species of North American flying squirrels (Glaucomys sabrinus and G...

We compared the endocrine status of the pituitary-gonad axis of wild and captive-reared greater amberjack (Seriola dumerili) during the reproductive cycle (April - July), reporting on the expression and release of the two gonadotropins for the first time in the Mediterranean Sea. Ovaries from wild females were characterized histologically as DEVELOPING in early May and SPAWNING capable in late May-July, the latter having a 3 to 4-fold higher gonadosomatic index (GSI). SPAWNING capable wild females exhibited an increase in pituitary follicle stimulating hormone (Fsh) content, plasma testosterone (T) and 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P), while almost a 10-fold increase was observed in pituitary luteinizing hormone (Lh) content...

Some evidence showed differences between layer and broiler embryo development. We recently showed that two adipokines, adiponectin and visfatin are expressed in the extra embryonic membranes and fluids. However, their role in the embryo development is unknown. Thus, our objectives were 1. to compare the expression of AdipoQ and its receptors AdipoR1 and AdipoR2 and visfatin in extra-embryonic annexes in broiler and layer breeders during the embryo development and 2. to investigate the role of two adipokines in embryo development in both broiler and layer breed after in ovo injection of blocking antibodies against chicken adiponectin or visfatin...

Adrenaline is one of the most important neurotransmitters in the central nervous system and is produced during stress. In this study, we investigated the modulatory role of adrenaline and adrenergic receptors on the neuroendocrine Dahlgren cells in the caudal neurosecretory system (CNSS) of olive flounder. Ex vivo electrophysiological recordings revealed that adrenaline significantly increased the firing frequency and altered the firing pattern of Dahlgren cells. Moreover, treatment with adrenaline led to a significant upregulation of ion channels and major hormone secretion genes in CNSS at the mRNA levels...

As a new member of the insulin-like growth factors (Igfs), Igf3 was reported to play a vital role in fish reproduction. However, in spotted steed, the function of Igf3 remains largely unknown. In the present study, we identified and characterized Igf3 gene in spotted steed. Structural analysis showed that Igf3 contained five domains (B, C, A, D, E) and six conserved cysteine residues. The expression of Igf3 mRNA and protein were increased during ovary development and peaked in the maturation stage. The subcellular localization of IGF3 was highly expressed in granulosa cells and theca cells...

The prss59.1 gene was identified as one of 11 genes that were highly upregulated during the induction of ovulation in zebrafish by using an in vivo ovulation assay. Previously, we conducted biochemical characterization of Prss59.1 and revealed it to be a trypsin-like proteolytic enzyme. In this study, we established a prss59.1 gene knockout strain using the CRISPR/Cas9 system. Phenotypic analysis of prss59.1 knockout fish showed that prss59.1 is associated with chorion elevation, a prominent event in egg activation during fertilization...

Anti-mullerian hormone (AMH) plays a crucial role in follicle regulation in mammals by preventing premature primordial follicle activation and restricting follicle development through reduction of FSH sensitivity and inhibition of FSH-induced increase of steroidogenic enzymes. AMH is produced by granulosa cells from growing follicles and expression declines at the time of selection in both mammalian and avian species. The role of AMH in chicken granulosa cells remains unclear, as research is complicated because mammalian AMH is not bioactive in chickens and there is a lack of commercially available chicken AMH...

Resistin (RETN), a recently discovered adipokine, is a cysteine-rich and secretory protein produced by adipocytes. RETN has been detected in several tissues, including human and laboratory animals' pancreas, wherein impairs glucose tolerance and insulin (INS) action and causes INS resistance. This study aims to evaluate the presence and expression of RETN in the pancreas of 15 adult female sheep reared on Apennine pastures, which show a decrease in their nutritional value due to the drought stress linked to the increasing summer aridity...

In earlier studies, wild-caught greater amberjack Seriola dumerili (Risso, 1810) males reared in sea cages showed gametogenesis impairment and low sperm production and quality. Here, we (a) examined if F1 hatchery-produced males reared in sea cages also exhibit reproductive dysfunctions and (b) evaluated the effects of gonadotropin releasing hormone agonist (GnRHa) administration through injections (GnRHainj ) or sustained-release implants (GnRHaimpl ), and human chorionic gonadotropin (hGC) injections on spermatogenesis/spermiation enhancement...

Whether there is a relationship between bats' dietary patterns and evolutionary endocrine pancreas adaptation is not clearly understood. Aiming to contribute to this topic, we evaluated some metabolic and structural parameters in the following adult bats: the frugivorous Artibeus lituratus, the nectarivorous Anoura caudifer, the hematophagous Desmodus rotundus, and the insectivorous Molossus molossus. A. lituratus and A. caudifer diets consist of high amounts of simple carbohydrates, while D. rotundus and M...

The thymus is an energy-consuming organ, and its metabolism changes with atrophy. Testosterone regulates thymus remodeling (atrophy and regeneration). However, the characteristics of the energy metabolism during testosterone-mediated thymic atrophy and regeneration remain unclear. In this study, we demonstrated that testosterone ablation (implemented by immunocastration and surgical castration) induced global metabolic changes in the thymus. Kyoto Encyclopedia of Genes and Genomes pathway enrichment for differential metabolites and metabolite set enrichment analysis for total metabolites revealed that testosterone ablation affected thymic glycolysis, glutamate metabolism, and fatty acid β-oxidation...