Central nervous system disorders represent a heterogeneous set of conditions triggered by genetic alterations, environmental exposures, infections, injuries, and even iatrogenic causes. These conditions impact a significant portion of the global population, posing serious concerns for public health. Even though progress has been made in understanding and treating some of these disorders, many others remain poorly understood, with research still in their early stages. For that, adapted experimental models are essential for deciphering the physiopathology of disorders and developing future therapeutic strategies. Within this context, zebrafish (Danio rerio) has emerged as a valuable model for central nervous system disorders, thanks to its high genetic and neuroanatomical homology with humans, the conservation in different aspects of cellular architecture and blood–brain barrier, and the remarkable regenerative ability of the CNS. This review presents the state of the art on zebrafish models for central nervous system disorders, presenting their potential in comprehending the pathophysiological processes and screening therapeutics.

Liquid whey (LW) is a nutrient-rich dairy by-product and a promising resource for animal nutrition. However, data regarding its impact on intestinal morphology and endocrine signaling are limited. Therefore, the current study aims to dissect those aspects. An experiment was conducted on 14 crossbred pigs divided into control (fed 3% of their body weight pelleted feed) and LW (fed 3% of their body weight supplemented with 1.5 L of LW) groups. The results show a significantly increased body weight gain in LW pigs during the second half of the experiment. Moreover, an increased ileal villus height, deeper crypts, and a thicker muscularis externa in the duodenum and jejunum have been reported in LW-fed pigs. Goblet cell count revealed a significant abundance of these cells in duodenal villi and jejunal crypts of the LW group, suggesting enhanced mucosal defense in all segments of LW-fed pigs. While Cholecystokinin8 and Galanin showed the same expression pattern among both groups and SI segments, the leptin expression was significantly higher in LW swine. These findings indicate that LW promotes growth, gut mucosa remodeling, and neuroendocrine signaling, thus supporting LW use as a functional dietary strategy with attention to the adaptation period.

Natural compounds are increasingly explored for their ability to modulate multiple molecular pathways involved in inflammation and oxidative stress and for their therapeutic potential. Among these, Opuntia ficus-indica (L.) Mill. has attracted growing interest due to its rich phytochemical profile; however, the biological properties of unripe fruits remain largely unexplored. In this study, a hydroalcoholic extract obtained from unripe O. ficus-indica fruits was characterized for its chemical composition, antioxidant capacity, and concentration-dependent embryotoxic profile and subsequently investigated in a zebrafish model of spinal cord injury (SCI). UHPLC-HRMS/MS analysis identified 14 secondary metabolites, mainly flavonoids and phenylpropanoid acids. Antioxidant activity was confirmed by DPPH and ABTS assays. An embryotoxicity assessment conducted according to OECD Test Guideline 236 revealed no mortality at concentrations below 100 µg mL⁻¹ and an LC₅₀ of 323.59 µg mL⁻¹ at 96 h post-fertilization, allowing the identification of non-toxic concentrations for subsequent in vivo experiments. Based on these results, the extract was tested in a larval zebrafish SCI transection model. Treated larvae showed improved locomotor recovery, particularly under continuous exposure, accompanied by modulation of molecular pathways involved in inflammation, neurotrophic support, and neurogenesis, including reduced pro-inflammatory cytokine expression and increased BDNF and Sonic Hedgehog signaling markers. Overall, these findings expand current knowledge on unripe O. ficus-indica and highlight its potential to modulate molecular pathways involved in SCI-induced damage and repair.

Ion channels play a crucial role in various physiological processes, yet their functions in the reproductive system remain underexplored. This study investigates the expression and the localization of ASIC2, ASIC4, and PIEZO2 ion channels in the reproductive tracts of prepubertal bitches. Western blotting on samples from eight prepubertal bitches confirmed the presence of these ion channels in ovarian, uterine, and uterine tubes tissues, and validated antibody specificity. Immunohistochemistry revealed that all primordial follicles expressed these ion channels, while only some developing follicles showed immunolabeling. These findings suggest ion channels’ potential involvement in oocyte differentiation and maturation. The localization of these channels in uterine tubes, uterine lining, and glandular epithelium suggests a role in tissue maintenance, oocyte transport, and embryo implantation. Additionally, their expression in the tunica media of reproductive vasculature points to a potential role in vascular regulation. Future studies are needed to elucidate the specific mechanisms underlying the role of these channels in reproductive physiology.

Flavonoids are a diverse group of natural polyphenolic compounds, recognized for their ability to modulate cellular pathways and mitigate the pathological processes of many neurodegenerative diseases. This study investigates the neurotrophic potential of a polyphenolic-rich lemon peel extract (Lpe) in a Zebrafish larvae spinal cord injury (SCI) model. To evaluate its potential effects, embryos were divided into six experimental groups: a baseline control group in which larvae were neither subjected to spinal cord injury nor treated (Ctrl Group); a group with larvae subjected to spinal cord injury at 3 dpf without treatment (SCI Group); a group treated continuously with Lpe (25 µg/mL) from 0 to 5 dpf without injury (Continuous Group); a group treated continuously with Lpe and injured at 3 dpf (Continuous SCI Group); a group treated with Lpe starting at 3 dpf without injury (Curative Group); and finally, a group injured at 3 dpf and treated simultaneously with Lpe (Curative SCI Group). Lpe treatment significantly downregulated proinflammatory cytokines (tnfa, il1b, and xcl8), and modulated the neuroregenerative pathways Wnt/β catenin, and neurotrophic factor Bdnf. Immunohistochemical analysis further revealed Sox2-positive cells localized around the central canal, consistent with activation of ependymal progenitor populations involved in injury-induced repair processes. These findings support the exploration of Lpe for mitigating SCI-induced damage.

Background/Aims: The Mediterranean killifish, Aphanius fasciatus (Valenciennes, 1821), is a small euryhaline and eurytherm cyprinodont. While its ecology and role as a bioindicator are well known, its anatomy remains poorly understood. This study aimed to provide the first detailed description of the digestive tract of A. fasciatus, from the oropharyngeal cavity to the rectum. Methods: An anatomical and morphological approach supported by light microscopy was applied to examine oral, pharyngeal, and intestinal structures in adult specimens. Results: The jaws bear tricuspids incisiform teeth, whereas the pharynx has caniniform teeth. The tongue forms a muscular thickening of the oral floor and aids swallowing. The oropharyngeal tract and esophagus lead to a dilated anterior intestinal region resembling a primitive stomach, with mucosal folds and mucus-secreting epithelium, but lacking gastric glands. This chamber functions mainly for food storage, absorption, and preparation rather than true gastric digestion. The intestine extends to the rectum, showing sexual dimorphism: females have a relaxed anus, males a more toned and folded structure. Conclusions: These findings provide essential baseline information for comparison with other experimental models and reinforce the suitability of A. fasciatus as a reliable model for anatomical and functional studies.