Whale tear glands in the bowhead and the beluga whales: Source and function
dolphin tursiops-truncatus; fluid; glands; harderian-gland; lacrimal gland; lactoferrin; lipocalin; localization; morphology; ocular glands; orbital whales; pacinian corpuscles; secretions
Orbital glands are found in many tetrapod vertebrates, and are usually separate structures, consisting of individual glands lying in the eyelids and both canthi of the orbit. In cetaceans, however, the orbital glandular units are less distinct and have been described by numerous authors as a single, periorbital mass. There are few histochemical and immunhistochemical studies to date of these structures. In this study, we examined the orbital glandular region of both the bowhead whale (Balaena mysticetus: Mysticeti) and the beluga whale (Delphinapterus leucas: Odontoceti) using histological, histochemical, and immunohistochemical techniques. Histologically, in the bowhead, three glandular areas were noted (circumorbital, including Harderian and lacrimal poles), palpebral (midway in the lower eyelid), and rim (near the edge of the eyelid). In the beluga, there was only a large, continuous mass within the eyelid itself. Histochemical investigation suggests neither sexual dimorphism nor age-related differences, but both whales had two cell types freely intermingling with each other in all glandular masses. Large cells (cell type 1) were distended by four histochemically distinct intracellular secretory granules. Smaller cells (cell type 2) were not distended (fewer granules) and had two to three histochemically distinct intracellular secretory granules. The beluga orbital glands had additional lipid granules in cell type 1. Counterintuitively, both lipocalin and transferrin were localized to cell type 2 only. This intermingling of cell types is unusual for vertebrates in whom individual orbital glands usually have one cell type with one to two different secretory granules present. The heterogeneity of the orbital fluid produced by cetacean orbital glands implies a complex function, or series of functions, for these orbital glands and their role in producing the tear fluid.
Rehorek Susan J; Stimmelmayr Rapahela; George John C; Suydam Robert; McBurney Denise M; Thewissen J G M
Journal of Morphology
2020
2020-03
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journalArticle
<a href="http://doi.org/10.1002/jmor.21099" target="_blank" rel="noreferrer noopener">10.1002/jmor.21099</a>
Lipocalin‐2 Protects Against Diet‐Induced Nonalcoholic Fatty Liver Disease by Targeting Hepatocytes.
FATTY liver; LIPOCALIN; LIVER disease treatment
Hepatocytes are the major source of hepatic lipocalin‐2 (LCN2), which is up‐regulated in response to inflammation, injury, or metabolic stress. So far, the role of hepatocyte‐derived LCN2 in the development of nonalcoholic fatty liver disease (NAFLD) remains unknown. Herein we show that overexpression of human LCN2 in hepatocytes protects against high fat/high cholesterol/high fructose (HFCF) diet–induced liver steatosis and nonalcoholic steatohepatitis by promoting lipolysis and fatty acid oxidation (FAO) and inhibiting de novo lipogenesis (DNL), lipid peroxidation, and apoptosis. LCN2 fails to reduce triglyceride accumulation in hepatocytes lacking sterol regulatory element‐binding protein 1. In contrast, Lcn2−/− mice have defective lipolysis, increased lipid peroxidation and apoptosis, and exacerbated NAFLD after being fed an HFCF diet. In primary hepatocytes, Lcn2 deficiency stimulates de novo lipogenesis but inhibits FAO. Conclusion: The current study indicates that hepatocyte LCN2 protects against diet‐induced NAFLD by regulating lipolysis, FAO, DNL, lipid peroxidation, and apoptosis. Targeting hepatocyte LCN2 may be useful for treatment of NAFLD. [ABSTRACT FROM AUTHOR]
Xu Yanyong; Zhu Yingdong; Jadhav Kavita; Li Yuanyuan; Sun Huihui; Yin Liya; Kasumov Takhar; Chen Xiaoli; Zhang Yanqiao
Hepatology Communications
2019
2019-06
<a href="http://doi.org/10.1002/hep4.1341" target="_blank" rel="noreferrer noopener">10.1002/hep4.1341</a>