Neural regulation of the homeostasis depends on healthy synaptic function. Adaptation of synaptic functions to physiological needs manifests in various forms of synaptic plasticity (SP), regulated by the normal hormonal regulatory circuits. During the past several decades, the hormonal regulation of animal and human organisms have become targets of thousands of chemicals that have the potential to act as agonists or antagonists of the endogenous hormones. As the action mechanism of these endocrine disrupting chemicals (EDCs) came into the focus of research, a growing number of studies suggest that one of the regulatory avenues of hormones, the morphological form of SP, may well be a neural mechanism affected by EDCs. The present review discusses known and potential effects of some of the best known EDCs on morphological synaptic plasticity (MSP). We highlight molecular mechanisms altered by EDCs and indicate the growing need for more research in this area of neuroendocrinology.

Background: Gold nanoparticles (AuNPs) have several beneficial properties that make them effective as intracellular drug carriers, and their potential for various diagnostic and therapeutic applications is gaining recognition. Depending on their size and shape, AuNPs can cross the central nervous system (CNS) through the blood–brain barrier (BBB). In the CNS, they can exert a variety of influences on neuronal and glial cells, which can be both supportive—promoting cell health and function—and cytotoxic, potentially leading to cellular damage. The hypothalamus (HT) is the first region where nanoparticles (NPs) interact, as this neuroendocrine center is particularly sensitive to factors in the systemic circulation due to its function and location. This area is affected by systemic factors, including pro-opiomelanocortin (POMC) neurons, which regulate metabolic function and maintain homeostasis. The activity of mitochondria within these cells influences their response to both external factors and the presence of AuNPs, thereby facilitating a complex interplay between nanoparticle interactions and cellular metabolism in this vital brain region. Aims: This study investigates how AuNPs, at different concentrations and exposure times under in vitro conditions, affect the mitochondrial activity of POMC neurons, aiming to provide a comprehensive understanding of the mechanisms in the HT. Methods: The study investigates the effect of varying gold nanoparticle concentrations on the mitochondrial activity of POMC neurons over treatment periods of 1, 15, 24, and 48 h. Mitochondrial activity was measured using a Seahorse XFp Analyzer to provide high-resolution insights. Additionally, mitochondrial functionality was assessed through the detection of reactive oxygen species (ROS) and cell viability. Results: The findings indicated that the effects of gold nanoparticles on mitochondrial activity depend significantly on their concentration and exposure time. Specifically, exposure leads to an increase in early response systems, the citric acid cycle, and proton efflux, ultimately resulting in the inhibition of mitochondrial function and ATP production in POMC cells. This disruption may affect hypothalamic regulation and energy metabolism.

Veterinary metabolomics has redefined bile acids (BAs) from simple digestive surfactants to systemic endocrine signals within a microbial–host metabolic axis. This review aims to evaluate how BA dysmetabolism acts as a central pathogenic factor in canine and feline disease. We analyze the BA pool’s integrity, which depends on a specialized functional guild, primarily Peptacetobacter hiranonis, responsible for 7α-dehydroxylation. We delineate two principal pathological profiles: (1) microbial collapse, characterized by secondary bile acid (SBA) depletion and compromised farnesoid X receptor (FXR) and Takeda G protein-coupled receptor 5 (TGR5) signaling, which exacerbates inflammation in chronic enteropathy (CE), protein-losing enteropathy (PLE), and exocrine pancreatic insufficiency (EPI); and (2) hepato-biliary spillover, wherein host-induced dysfunction results in primary bile acid (PBA) excess. Recent data have linked these disruptions to skeletal health, feline renal fibrosis, cardiac remodeling in myxomatous mitral valve disease (MMVD), and neuroinflammation in epilepsy and hepatic encephalopathy. The discovery of microbially conjugated bile acids (MCBAs) and microbial extracellular vesicles (MEVs) reveals highly specific, vesicle-mediated communication pathways impacting systemic health. Diagnostic protocols should prioritize functional profiling, including the dysbiosis index (DI), serum conjugated BA analysis, and SBA/PBA ratios. Clinical management is moving beyond empirical fecal microbiota transplantation (FMT), towards precision synthetic microbial consortia (SynComs), neuroprotective BAs like tauroursodeoxycholic acid (TUDCA), and molecular postbiotics to restore the collaborative metabolome.

The sex of crocodilians is determined by the temperature to which the eggs, and hence the developing embryo are exposed during critical periods of development. Temperature-dependent sex determination is a process that occurs in all crocodilians and numerous other reptile taxa. The study of artificial incubation temperatures in different species of crocodiles and alligators has determined the specific temperature ranges that result in altered sex ratios. It has also revealed the precise temperature thresholds at which an equal number of males and females are generated, as well as the specific developmental period during which the sex of the hatchlings may be shifted. This review will examine the molecular basis of the sex-determination mechanism in crocodilians elucidated during recent decades. It will focus on the many patterns and theories associated with this process. Additionally, we will examine the consequences that arise after hatching due to changes in incubation temperatures, as well as the potential benefits and dangers of a changing climate for crocodilians who display sex determination based on temperature.

Extracellular vesicles (EVs) are key mediators of intercellular communication across biological kingdoms, with central roles in immune regulation and disease processes. Despite shared structural features, EVs derived from bacteria, plants, and mammalian cells differ substantially in their biogenesis, molecular composition, and immunological functions. EV formation pathways generate vesicles with distinct cargo profiles, including pathogen-associated molecular patterns (PAMPs) in bacterial EVs, regulatory small RNAs in plant-derived vesicles, and cytokines, microRNAs, and antigen-presenting complexes in mammalian EVs. Differences in cargo result in divergent immune outcomes. Bacterial EVs predominantly activate innate immunity via pattern recognition receptors such as Toll-like receptors, whereas plant-derived EVs exhibit low immunogenicity and mediate cross-kingdom RNA interference. In contrast, mammalian EVs primarily regulate immune responses by modulating antigen presentation and cytokine signaling. These findings support a framework in which EV origin determines immunological function and therapeutic applicability. This perspective highlights the importance of selecting appropriate EV sources for vaccine development, regenerative medicine, and targeted delivery strategies, while addressing current challenges related to heterogeneity, standardization, and safety.

Collagen, long regarded as the inert structural scaffold of the extracellular matrix, is now recognised as a source of bioactive signaling molecules: enzymatic hydrolysis releases low-molecular-weight bioactive collagen peptides that act systemically. This narrative review synthesises in vitro, animal-model, and veterinary clinical evidence with explicit differentiation of evidence levels; literature was identified through structured searches of PubMed, Web of Science, and Google Scholar, covering peer-reviewed, English-language reports published between 2000 and January 2026, without a formal systematic protocol. Across rodent, porcine, and human pharmacokinetic studies, orally administered collagen hydrolysate is efficiently absorbed, with a fraction reaching the circulation as intact prolyl-hydroxyproline and hydroxyprolyl-glycine through the conserved PEPT1/PEPT2 transporters; reported bioavailability varies with source, dose, and method, so no single value generalises across species. Native collagen and larger collagen fragments engage structure-dependent receptors in vitro (α2β1 integrins, DDR1/DDR2, GPVI, LAIR-1/2) that require triple-helical or Gly-Pro-Hyp presentation, whereas it is not established that the di- and tripeptides that reach the circulation after oral dosing engage them; their systemic actions are partly attributable to intracellular routes, including the Keap1–Nrf2 axis, HDAC/HAT modulation, and glycine-dependent glutathione synthesis. The gut–collagen peptide axis, a model derived from rodent and cell-culture data, links microbial bile acid remodeling and FXR/TGR5 signaling to systemic effects. Current evidence supports validated use in canine and equine osteoarthritis; species-specific bioavailability studies in dogs and cats remain the priority.