Arterial and venous supply of the Harderian gland in hens.

Background: The Harderian gland in domestic birds is a major paraocular excretory gland that has an important role in tear production as well as in the immune protection of the conjunctiva surface. Aim: The aim of this research was to investigate the arterial and venous supply of the gland in hens and provide valuable and useful information for future research. Methods: The research was conducted on 26 adult hens, provenience of Lohmann Brown. For the identification and determination of blood vessels, we used the vascular corrosion cast technique in conjunction with the transmission electron microscope (TEM). Results: The casts showed that the gland receives the arterial supply via branches of a. ophthalmotemporalis and a. nasalis communis and these arteries are accompanied by the corresponding veins. Ultrastructural analyses showed the presence of fenestrated capillaries, which indicates the possibility for permeability of larger molecules. Conclusion: The present research gives important and detailed information about the arterial and venous supply of the Harderian gland in hens that may serve as guidelines for future vascular and morphological investigations.

Dimorphic Regulation of the MafB Gene by Sex Steroids in Hamsters, Mesocricetus auratus.

MafB is a transcription factor that regulates macrophage differentiation. Macrophages are a traditional feature of the hamster Harderian gland (HG); however, studies pertaining to MafB expression in the HG are scant. Here, the full-length cDNA of the MafB gene in hamsters was cloned and sequenced. Molecular characterization revealed that MafB encodes a protein containing 323 amino acids with a DNA-binding domain, a transactivation domain, and a leucine zipper domain. qPCR assays indicated that MafB was expressed in different tissues of both sexes. The highest relative expression levels in endocrine tissues were identified in the pancreas. Gonadectomy in male hamsters was associated with significantly higher mRNA levels in the HG; replacement with dihydrotestosterone restored mRNA expression. The HG in male hamsters contained twofold more MafB mRNA than the HG of female hamsters. Adrenals revealed similar mRNA relative expression levels during the estrous cycle. The estrous phase was associated with higher mRNA levels in the ovary. A significantly up-regulated expression and sexual dimorphism of MafB was found in the pancreas. Therefore, MafB in the HG may play an active role in the macrophage differentiation required for phagocytosis activity and intraocular repair. Additionally, sex steroids appear to strongly influence the MafB expression in the HG and pancreas. These studies highlight the probable biological importance of MafB in immunological defense and pancreatic ß cell regulation.

Harderian Gland Development and Degeneration in the Fgf10-Deficient Heterozygous Mouse.

The mouse Harderian gland (HG) is a secretory gland that covers the posterior portion of the eyeball, opening at the base of the nictitating membrane. The HG serves to protect the eye surface from infection with its secretions. Mice open their eyelids at about 2 weeks of age, and the development of the HG primordium mechanically opens the eye by pushing the eyeball from its rear. Therefore, when HG formation is disturbed, the eye exhibits enophthalmos (the slit-eye phenotype), and a line of Fgf10+/- heterozygous loss-of-function mice exhibits slit-eye due to the HG atrophy. However, it has not been clarified how and when HGs degenerate and atrophy in Fgf10+/- mice. In this study, we observed the HGs in embryonic (E13.5 to E19), postnatal (P0.5 to P18) and 74-week-old Fgf10+/- mice. We found that more than half of the Fgf10+/- mice had markedly degenerated HGs, often unilaterally. The degenerated HG tissue had a melanized appearance and was replaced by connective tissue, which was observed by P10. The development of HGs was delayed or disrupted in the similar proportion of Fgf10+/- embryos, as revealed via histology and the loss of HG-marker expression. In situ hybridization showed Fgf10 expression was observed in the Harderian mesenchyme in wild-type as well as in the HG-lacking heterozygote at E19. These results show that the Fgf10 haploinsufficiency causes delayed or defective HG development, often unilaterally from the unexpectedly early neonatal period.

Breed and timepoint-based analysis of chicken harderian gland transcriptome during Newcastle disease virus challenge.

Introduction: Newcastle disease is a highly infectious disease caused by the Newcastle Disease Virus (NDV) and has a devastating financial impact on the global chicken industry. It was previously established that Leghorn and Fayoumi breeds of chicken exhibit variable resistance against NDV infection. The harderian gland is the less studied tissue of the chicken, known to play an essential role in the immune response. Methods: Our previous study, we reported differential gene expression and long noncoding RNAs (lncRNAs) between challenged and non-challenged chickens in the Harderian gland transcriptomic data. Now, we report the analysis of the same data studying the differential expression patterns between Leghorn and Fayoumi and between different timepoints during disease. First, the pipeline FHSpipe was used for identification of lncRNAs, followed by differential expression analysis by edgeR (GLM), functional annotation by OmicsBox, co-expression analysis using WGCNA and finally validation of selected lncRNAs and co-expressing genes using qRT-PCR. Results: Here, we observed that Leghorn showed a higher number of upregulated immune-related genes than Fayoumi in timepoint-based analysis, especially during the initial stages. Surprisingly, Fayoumi, being comparatively resistant, showed little difference between challenged and non-challenged conditions and different time points of the challenge. The breed-based analysis, which compared Leghorn with Fayoumi in both challenged and non-challenged conditions separately, identified several immune-related genes and positive co-expressing cis lncRNAs to be upregulated in Fayoumi when compared to Leghorn in both challenged and non-challenged conditions. Discussion: The current study shows that Leghorn, being comparatively more susceptible to NDV than Fayoumi, showed several immune-related genes and positive co-expressing cis lncRNAs upregulated in challenged Leghorn when compared to non-challenged Leghorn and also in different timepoints during challenge. While, breed-based analysis showed that there were more upregulated immune genes and positive cis-lncRNAs in Fayoumi than Leghorn. This result clearly shows that the differences in the expression of genes annotated with immune-related GO terms and pathways, i.e., immune-related genes and the co-expressing cis-lncRNAs between Leghorn and Fayoumi, and their role in the presence of differences in the resistance of Leghorn and Fayoumi chicken against NDV. Conclusion: These immune-genes and cis-lncRNAs could play a role in Fayoumi being comparatively more resistant to NDV than Leghorn. Our study elucidated the importance of lncRNAs during the host defense against NDV infection, paving the way for future research on the mechanisms governing the genetic improvement of chicken breeds.

Differential Impact of Massachusetts, Canadian 4/91, and California (Cal) 1737 Genotypes of Infectious Bronchitis Virus Infection on Lymphoid Organs of Chickens.

Infectious bronchitis virus (IBV) induces severe economic losses in chicken farms due to the emergence of new variants leading to vaccine breaks. The studied IBV strains belong to Massachusetts (Mass), Canadian 4/91, and California (Cal) 1737 genotypes that are prevalent globally. This study was designed to compare the impact of these three IBV genotypes on primary and secondary lymphoid organs. For this purpose, one-week-old specific pathogen-free chickens were inoculated with Mass, Canadian 4/91, or Cal 1737 IBV variants, keeping a mock-infected control. We examined the IBV replication in primary and secondary lymphoid organs. The molecular, histopathological, and immunohistochemical examinations revealed significant differences in lesion scores and viral distribution in these immune organs. In addition, we observed B-cell depletion in the bursa of Fabricius and the spleen with a significant elevation of T cells in these organs. Further studies are required to determine the functional consequences of IBV replication in lymphoid organs.

Enzyme histochemical characterization of orbital glands in fetuses of Indian buffalo (Bubalus bubalis).

Background: The orbital glands, viz. lacrimal gland, superficial and deep gland of third eyelid (LG, SGT and HG), are important for normal eye functions. These glands have different functions in various animals. The information about the enzyme histochemical nature of prenatal orbital glands in Indian buffalo seems to be unavailable. Therefore, the study was planned on orbital glands of six full term recently died fetuses from animals with dystocia. Methods: The frozen sections of all these glands were subjected to standard localization protocols for Alkaline Phosphatase (AKPase), Glucose 6 phosphatase (G-6-Pase), Lactate dehydrogenase (LDH), Succinate dehydrogenase (SDH), Glucose 6 phosphate dehydrogenase (G-6-PD), Nicotinamide Adenine Dinucleotide Hydrogen Diaphorase (NADHD), Nicotinamide Adenine Dinucleotide Phosphate Hydrogen diaphorase (NADPHD), Dihydroxy phenylalanine oxidase (DOPA-O), Tyrosinase, non-specific esterase (NSE) and Carbonic anhydrase (CAse). Results: The results revealed a mixed spectrum of reaction for the above enzymes in LG, SGT and HG which ranged from moderate (for LDH in SGT) to intense (for most of the enzymes in all three glands). However, DOPA-O, Tyrosinase and CAse did not show any reaction. From the present study, it can be postulated that the orbital glands of fetus have a high activity of metabolism as it has many developmental and functional activities which were mediated with the higher activity of the enzymes involved.

Dimorphic frataxin and its gene regulation by sex steroids in hamsters.

The role of frataxin (FXN) has been studied extensively in Friedreich ataxia patients, however, the molecular bases underlining the sex steroid-dependent gene expression profiles of FXN in adult tissues are unknown. I describe the molecular characterization of hamster FXN by examining the sexually dimorphic expression and its regulation by sex steroids. Sequence analysis of FXN cDNA showed 630 bp-long ORF encoding 209 amino acids. qPCR analysis revealed that FXN is detected in a wide range of tissues, with the highest expression in the heart, liver, and epididymis, and the weakest expression in the lung, spleen, uterus, and gut. In the male Harderian gland (HG), castration decreased FXN expression, while dihydrotestosterone (DHT) administration reestablished levels. FXN expression levels were higher in the male HG than the female HG. Expression levels in endocrine tissues showed a certain degree of sexual dimorphism; the transcript in the testis was significantly higher than those in the ovary. The effects of the estrous cycle on FXN expression remained unchanged in the HG, ovary, and adrenal glands; however, in the pancreas, the FXN mRNA was overexpressed during proestrus and exhibited sexual dimorphism as compared to the male pancreas. The mRNA expression results indicated that Harderian FXN may play a dynamic role in intracellular Fe of heme required for processing cytochromes and other hemeproteins, also suggesting that the moderate sexual dimorphism present in the HG and gonads could be regulated by androgens, while sexually dimorphic expression of FXN in the female pancreas may be controlled by sex steroids.

High-fat diet affects autophagy and mitochondrial compartment in rat Harderian gland.

The Harderian gland (HG) of Rattus norvegicus is an orbital gland secreting lipids that accumulate in excess under condition of increased lipid metabolism. To study the response elicitated by lipid overload in rat HG, we housed the animals in thermoneutral conditions (28-30°C) in association to high fat diet (HFD). In HFD rats alterated blood lipid levels result in lipid accumulation in HG as demonstrated by the increased gland weight and histochemical/ultrastructural analyses. The HFD-caused oxidative stress forces the gland to trigger antioxidant defense mechanisms and autophagic process, such as lipophagy and mitophagy. Induction of mitochondrial DNA (mtDNA) damage and repair was stronger in HFD-rat HGs. An increase in marker expression levels of mitochondrial biogenesis, fission, and fusion occurred to counteract mtDNA copy number reduction and mitophagy. Therefore, the results demonstrate that rat HG activates autophagy as survival strategy under conditions of increased lipid metabolism and suggest a key role for mitophagy and membrane dynamics in the mitochondrial adaptive response to HFD.

Morphological and functional relationship between the orbital gland and olfaction in Upupa epops (hoopoe) and Bubulcus ibis (cattle egret).

This study used both anatomical and histological techniques to investigate the orbital gland's topographic relationship with the surrounding system, using the hoopoe and cattle egret as biological models. Hoopoe has a spindle-shaped lacrimal gland that is suspended on the lateral edge of the frontal bone, whereas cattle egret has a tiny lacrimal gland that is embedded posteriorly within the periorbital fascia. The hoopoe's lacrimal gland has a single duct that runs parallel to the nasolacrimal duct and opens into the posterior nostril hole. In the cattle egret, the tubule-alveolar secretory components comprise neutral and acid glycosaminoglycan. In addition, the Harderian gland is found in both these species, but their draining ducts differ; the Harderian gland of the hoopoe opens into the anterodorsal to the conjunctival fornix, whereas the Harderian gland of the egret opens anteriorly. In both hoopoe and egret, the secretions of Harderian gland include neutral and acid glycosaminoglycan. The Harderian gland is categorized as type II in hoopoe and type I in cattle egrets. The present results concluded that both orbital glands of two bird species studied play an essential role in eye health, where cleaning and lubrication of the cornea surface. Furthermore, the lacrimal gland's location and secretory features may strengthen the olfactory sensitivity of hoopoe, which relies heavily on scent to locate their food, whereas egret relies heavily on visual cues.

Lacrimal Gland and Orbital Lesions in LatY136F Knock-in Mice, a Model for Human IgG4-Related Ophthalmic Disease.

PURPOSE: LatY136F knock-in mice were recently proposed as an animal model for immunoglobulin G4 (IgG4)-related disease. In this study, we investigated whether LatY136F knock-in mice exhibit ophthalmic lesions, specifically in the lacrimal and Harderian glands. METHODS: Lacrimal glands, Harderian glands, and adherent lymphoid follicle lesions were dissected from LatY136F knock-in mice and wild type (WT) C57BL/6 mice between 6 and 24 weeks of age. Tissues were stained with hematoxylin-eosin, immunoglobulin G (IgG), and anti-IgG1, a homologue of human IgG4, for histopathological analysis. RESULTS: In LatY136F knock-in mice, IgG1-positive cells infiltrated the space between the lacrimal gland acinar cells at 6, 9, 12, and 20 weeks or order, and the number of IgG1-positive cells did not differ significantly between these age groups. Infiltration of IgG1-positive inflammatory cell was also observed in the Harderian glands of LatY136F knock-in mice at all ages. The ratio of IgG1/IgG-positive cells averaged 80 and 67% in the lacrimal and Harderian glands, respectively. Dense IgG1-positive lesions were also seen in tissues adjacent to the lacrimal and Harderian glands in some LatY136F knock-in mice. In contrast, there were almost no IgG1-positive cell infiltrates in the lacrimal and Harderian glands of WT mice. CONCLUSION: IgG1-positive cells infiltrate the lacrimal and Harderian glands of LatY136F knock-in mice, indicating that LatY136F knock-in mice could be a representative animal model for IgG4-related ophthalmic disease.

Preliminary study of the ameliorative effects of melatonin on cadmium-induced morphological and biochemical alterations in the rat Harderian gland.

Herein is reported, for the first time in the rat Harderian gland (HG), the counteractive action of melatonin (Mlt), a well-known antioxidant radical scavenger, on the increased oxidative stress damages induced by a pro-oxidant substance, cadmium (Cd), an environmental pollutant also considered as endocrine disruptor. HG, an infraorbital gland present in almost all terrestrial vertebrates, produces a lipid secretion to lubricate the eyeball, as well as porphyrin/Mlt as light transducers. Moreover, HG is an extra-gonadal source of steroid sex hormones. Via ex vivo experiments lasting for 24 h, we verified the increased lipid peroxidation in Cd-treated glands, producing morphological alteration of the glandular epithelium, as well as an increased porphyrins accumulation. Moreover, Cd also induced a decreased protein level of the steroidogenic enzymes steroidogenic acute regulatory (StAR) and 3ßHSD, and an increased mast cell number. Results obtained with Mlt cotreatment demonstrated that it decreased the levels of Cd-induced oxidative damage, with reversal of all the observed modification. Furthermore, the TUNEL assay showed that the increased number of apoptotic cells in Cd-treated HG was counteracted by the contemporaneous Mlt administration. Results confirmed that Mlt treatment restored the levels of two autophagy markers, LC3 and p62, counteracting the autophagy Cd-induced. Interestingly, the positive effects of Mlt alone were highlighted by the decreased rate of lipid peroxidation as compared with the control, confirming its antioxidant action. Combined data further confirmed the antioxidant action of Mlt in counteracting the degeneration provoked by reactive oxygen species (ROS) in the rat HG, a tissue extremely susceptible to oxidative stress condition.

Dry eye symptoms in interferon regulatory factor 3-deficient mice due to herpes simplex virus infection in harderian gland and lacrimal gland.

PURPOSE: Dry eye syndrome (DES) is a multifactorial ocular disorder. The possible pathogens and pathogenic mechanisms for virus-related dry eye disease are largely unknown. The current study aimed to provide evidence for mechanisms contributing to DES induced by herpes simplex virus (HSV) infection in the harderian gland (HG) and lacrimal gland (LG). METHODS: We recorded the dry eye-like cornea pathology of irf3-/- mice infected with HSV-1 till 8 months of age. The slit-lamp and confocal microscopy was used to observe the corneal defects. TUNEL was used to detect the corneal apoptosis. Human corneas suffered from herpes stromal keratitis (HSK) were also analyzed as a comparison. Then, we measure the aqueous tear production with a phenol red thread test in irf3-/-mice, and recorded their tear film breakup time. HGs and LGs were sectioned and analyzed using HE and oil-red-O staining. For molecular signaling pathway analysis, we used mRNA sequencing to explore the related gene ontology. Western blotting (WB) and real-time reverse transcription-quantitative polymerase chain reaction were used to verify the level of the Akt signaling pathway and related inflammatory factors. RESULTS: Inoculated irf3-/- mice tended to develop dry eye-like symptoms, such as corneal keratinization, corneal cell apoptosis, and tear reduction. The HGs and LGs of irf3-/- mice showed increased level of HSV-1, and exhibited inflammatory pathological changes and impaired function, which explained the damaged tear film. WB and mRNA sequencing indicated that enhanced PI3K-Akt pathway in irf3-/- mice might account for the higher susceptibility to HSV infection. CONCLUSIONS: We observed evidence of DES in irf3-/- mice induced by HSV-1 infection in the HGs and LGs, which may introduce a potential novel target for DES treatment.

Hamster DAX1: Molecular insights, specific expression, and its role in the Harderian gland.

DAX1 plays an essential role in the differentiation and physiology of the Hypothalamic-Pituitary-Adrenal-Gonadal (HPAG) axis during embryogenesis. However, in adult tissues, in addition to the HPAG axis, evidence has not been found for its differential expression and function. We isolated the DAX1 cDNA to analyze its tissue localization and gene expression profiles in male and female hamsters' Harderian glands (HGs), Mesocricetus auratus. The isolated cDNA clone contains 1848 base pairs (bp), and a 1428-bp open reading frame (ORF) encodes a 476 amino acid protein. Sequence alignments and the phylogenetic tree display a relevant percentage of similarity with human (66%), rat (81%), and mouse (84%) sequences. In adult tissues, the mRNA distribution demonstrated that DAX1 is present in testis, ovaries, and male and female HGs. The highest expression profiles were identified in the adrenal glands, where females exhibit higher mRNA levels than males. The sexually dimorphic expression of DAX1 in adrenals suggests that its presence could be associated with regulating, functioning, and maintaining this endocrine tissue. These findings indicate that the DAX1 gene is limitedly expressed in adult tissues. In the HGs, we demonstrate the absence of sexually dimorphic gene expression. Our results suggest that DAX1 might have an additional physiological function outside of the HPAG axis, specifically in the HG, which may be required for the regulation of intracrine steroidogenesis, secretion, and maintenance of exocrine tissue.

Novel Lipids of the Rabbit Harderian Gland Improve Tear Stability in an Animal Model of Dry Eye Disease.

Purpose: Instability of the tear film leads to evaporative dry eye disease (EDED), but the Harderian gland in some terrestrial vertebrates may produce novel lipids that stabilize the tear film and protect against dry eye. Here, the nonpolar lipids in the Harderian gland and tears of the rabbit but absent in human tears were identified and tested in preclinical studies to determine whether they could treat severe EDED. Methods: Lipids were identified primarily by atmospheric pressure chemical ionization mass spectrometry (MS) and fragmentation MS/MS. An identified lipid was synthesized and formulated as an emulsion and as a cyclodextrin (CD) clathrate. Following doses with test agents and controls, tear film breakup time (TBUT), tear production, corneal fluorescein staining, macrophage infiltration, and goblet cell survival were measured using standard tests at 0, 2 and 4 weeks in an animal model of EDED. Results: The lipid emulsion increased TBUT (P < 0.01) and tear production (P < 0.05), while it decreased corneal staining (P < 0.01) compared to controls. The lipid CD formulation increased TBUT (P < 0.05) and tear production (P < 0.05) but had no significant effect on the remaining test parameters. There were no differences in macrophage infiltration and conjunctival impression cytology scores between the formulations and their vehicle controls. Conclusions: Lipids in the rabbit Harderian gland and tears differ from those identified in human meibum and tears. These unique rabbit lipids may confer a protective effect against EDED and, as supplements to human tears, fulfill a similar role.

Melatonin Ameliorates Autophagy Impairment in a Metabolic Syndrome Model.

Metabolic syndrome is a global health problem in adults and its prevalence among children and adolescents is rising. It is strongly linked to a lifestyle with high-caloric food, which causes obesity and lipid metabolism anomalies. Molecular damage due to excessive oxidative stress plays a major role during the development of metabolic syndrome complications. Among the different hormones, melatonin presents strong antioxidant properties, and it is used to treat metabolic diseases. However, there is not a consensus about its use as a metabolic syndrome treatment. The aim of this study was to identify melatonin effects in a metabolic syndrome model. Golden hamsters were fed with 60% fructose-enriched food to induce metabolic syndrome and were compared to hamsters fed with regular chow diet. Both groups were also treated with melatonin. Fructose-fed hamsters showed altered blood lipid levels (increased cholesterol and LDL) and phenotypes restored with the melatonin treatment. The Harderian gland (HG), which is an ideal model to study autophagy modulation through oxidative stress, was the organ that was most affected by a fructose diet. Redox balance was altered in fructose-fed HG, inducing autophagic activation. However, since LC3-II was not increased, the impairment must be in the last steps of autophagy. Lipophagy HG markers were also disturbed, contributing to the dyslipidemia. Melatonin treatment improved possible oxidative homeostasis through autophagic induction. All these results point to melatonin as a possible treatment of the metabolic syndrome.

Harderian SOX9: Molecular characterization and its dimorphic expression in hamster.

The molecular action of SOX9 can promote lipogenesis. Because the hamster Harderian gland (HG) synthesizes lipids and exhibits sexual dimorphism, this study aimed to identify and characterize Harderian SOX9. We examined the tissue distribution and expression profiles of SOX9 in hamster Mesocricetus auratus HGs. The full-length SOX9 cDNA sequence [3649-base pairs (bp)] contains an 81-bp 5' untranslated region (UTR), a 3' UTR of 2044-bp, an open reading frame (ORF) of 1524-bp, and a polyadenylation signal (AATAAA) at 19-bp upstream of poly(A) tail. The cDNA encodes a 507 amino acid protein containing the potential DNA-binding domain known as the HMG box. BLAST analysis revealed 99%, 99%, and 97% identity with the SOX9 of mouse, rat, and human, respectively. High expression levels were also observed in the testis, cerebellum, and hypothalamus. qPCR analysis demonstrated that SOX9 is expressed more abundantly in the HGs of males than in females. Sexually dimorphic expression of SOX9 suggests that differential expression between male and female HGs could be under the regulation of sex steroids. SOX9 might play a similar role in regulating exocrine secretions of lipids; these could occur downstream of FGF signaling - as found during embryogenesis - and/or androgen signaling.

Change on apoptosis, autophagy and mitochondria of the Harderian gland in Cricetulus barabensis during age.

Harderian gland (HG) plays an important role in the physiological adaptation to terrestrial life, however, the mechanisms underlying the changes in the structure and function of the HG during aging remain unclear. This study investigated autophagy and apoptosis in the HG of striped dwarf hamsters (Cricetulus barabensis) of different ages (sub-adult, adult and aged groups) in both males and females. The results showed that LC3II/LC3I and puncta of LC3 were significantly higher in adult and aged individuals than sub-adults, whereas P62 decreased with age. Bax/bcl2was the highest in sub-adults of male and female individuals. Caspase3 activity was the highest in sub-adults of male and female individuals, and the citrate synthase activity was highest in sub-adults of females. ATP synthase, citrate synthase, dynamin-related protein 1 and mitochondrial fission factor (Mff) were the highest in sub-adults of females. Peptidylglycine α-amidating monooxygenase were the highest in the aged group, and those of gonadotropin-releasing hormone was the highest in the adult group. LC3II/LC3I, P62, Drp1, Fis, and bax/bcl2 were higher in males than that in females. These results suggest that apoptosis mainly affects growth and development in the HG, whereas autophagy affects aging. The difference of the HG weight and mitochondrial function between sexes is mainly related to the apoptosis.

The Harderian gland: Endocrine function and hormonal control.

The Harderian gland (HG) is an exocrine gland located within the eye socket in a variety of tetrapods. During the 1980s and 1990s the HG elicited great interest in the scientific community due to its morphological and functional complexity, and from a phylogenetic point of view. A comparative approach has contributed to a better understanding of its physiology. Whereas the chemical nature of its secretions (mucous, serous or lipids) varies between different groups of tetrapods, the lipids represent the more common component among different species. Indeed, besides being an accessory to lubricate the nictitating membrane, the lipids may have a pheromonal function. Porphyrins and melatonin secretion is a feature of the rodent HG. The porphyrins, being phototransducers, could modulate HG melatonin production. The melatonin synthesis suggests an involvement of the HG in the retinal-pineal axis. Finally, StAR protein and steroidogenic enzyme activities in the rat HG suggests that the gland contributes to steroid hormone synthesis. Over the past twenty years, much has become known on the hamster (Mesocricetus auratus) HG, unique among rodents in displaying a remarkable sexual dimorphism concerning the contents of porphyrins and melatonin. Mainly for this reason, the hamster HG has been used as a model to compare, under normal conditions, the physiological oxidative stress between females (strong) and males (moderate). Androgens are responsible for the sexual dimorphism in hamster and they are known to control the HG secretory activity in different species. Furthermore, HG is a target of pituitary, pineal and thyroid hormones. This review offers a comparative panorama of the endocrine activity of the HG as well as the hormonal control of its secretory activity, with a particular emphasis on the sex dimorphic aspects of the hamster HG.

Immunomodulatory effect of ginseng stem-leaf saponins and selenium on Harderian gland in immunization of chickens to Newcastle disease vaccine.

Our previous study demonstrated that ginseng stem-leaf saponins (GSLS) in combination with selenium (GSLS-Se) have adjuvant effect on the live vaccine of Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) in intraocular-and-intranasal immunization in chickens. The present study was to investigate the potential molecular mechanisms involved in the immunomodulation of GSLS-Se on the Harderian gland (HG). It was found that the window allowing animals susceptible to infections due to low antibody titers became smaller or even completely closed because of increased NDV-specific HI titers when NDV vaccine and GSLS-Se were coadministered for immunization at early life in chickens. In addition, NDV-specific sIgA and the numbers of IgG+, IgA+, IgM+ plasma cells were significantly more in GSLS-Se group than the control in the HGs. Transcriptome analysis of HGs identified 1184 differentially expressed genes (DEGs) between GSLS-Se treated and non-treated groups. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses identified 42 significantly enriched GO terms and 13 canonical immune pathways. These findings indicated that GSLS-Se might exert immunomodulatory effects through influencing the antioxidant regulation and modulating the activity of immune related enzymes. Besides, Toll-like receptor (TLR) signaling pathway and mitogen-activated protein kinase (MAPK) signaling pathway might be involved primarily in the immunomodulation. Therefore, enhanced antibody responses in GSLS-Se group may be attributed to the immunomodulatory effects of GSLS-Se on the immune-related gene profile expressed in the immunocompetent cells of the HGs.