The Harderian gland of the Mexican volcano mouse Neotomodon alstoni alstoni (Merriam 1898): a morphological and biochemical approach

Short-term High Fructose Intake Reprograms the Transcriptional Clock Rhythm of the Murine Extraorbital Lacrimal Gland

Purpose

To determine whether high fructose intake (HFI) influences the daily transcriptional clock rhythms of murine extraorbital lacrimal glands (ELGs).

Methods

Timed ELGs were collected from two groups of C57BL/6J mice subjected to a 12-hour light/12-hour dark (LD) cycle for 10 days; the first group received water-only feeding and the second received water with 15% fructose. Total RNA was extracted and subjected to RNA sequencing. A JTK_CYCLE algorithm and computational software were used to determine the periodicity, rhythmicity, and amplitude of the cycling transcripts. The rhythmic transcripts from different conditions were analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.

Results

HFI feeding caused massive remodeling of the preexisting rhythmic genes in the normal control (NC)-fed ELGs. The induced transcripts in HFI-fed mice resulted in a profound reorganization of the coordinated transcriptional oscillations and KEGG pathways. Moreover, HFI feeding significantly altered the distribution of the KEGG pathways over an LD in the ELGs. Finally, we found that the ELGs have a robust core clock machinery and HFI feeding altered amplitude and the peak phase of clock gene transcriptional oscillation in ELGs.

Conclusions

Short-term HFI reprograms the daily transcriptomic oscillation of murine ELGs. This information may deepen our understanding of the outcomes of lacrimal glands altered by nutritional challenge.

The volcano mouse Neotomodon alstoni of central Mexico, a biological model in the study of breeding, obesity and circadian rhythms

The "Mexican volcano mouse" Neotomodon alstoni, is endemic of the Transverse Neovolcanic Ridge in central Mexico. It is considered as least concern species and has been studied as a potential laboratory model from different perspectives. Two lines of research in neuroendocrinology have been addressed: reproduction and parental care, particularly focused on paternal attention and the influence of testosterone, and studies on physiology and behavior of circadian rhythms, focused on the circadian biology of the species, its circadian locomotor activity and daily neuroendocrine regulation of metabolic parameters related to energy balance. Some mice, when captive, spontaneously develop obesity, which allows for comparisons between lean and obese mice of daily changes in neuronal and metabolic parameters associated with changes in food intake and locomotor activity. This review includes studies that consider this species an attractive animal model where the alteration of circadian rhythms influences the pathogenesis of obesity, specifically with the basic regulation of food intake and metabolism and differences related to sex. This study can be considered as a reference to the comparative animal physiology among rodents.

Obesity alters circadian behavior and metabolism in sex dependent manner in the volcano mouse Neotomodon alstoni

The aim of the present study is to evaluate whether circadian locomotor activity, and the daily profile of plasma parameters related to metabolic syndrome (nutrients: glucose and triacylglycerides, and hormones: insulin and leptin), differ between male and female Neotomodon alstoni mice, both lean and obese. Young adult animals were captured in the field and kept at the laboratory animal facility. After 6 to 7 months feeding the animals ad libitum with a regular diet for laboratory rodents, 50-60% of mice became obese. Comparisons between sexes indicated that lean females were more active than males; however obese females reduced their nocturnal activity either in LD or DD, and advanced the phase of their activity-onset with respect to lights off. No differences in food intake between lean and obese mice, either during the day or night, were observed. Daily profiles of metabolic syndrome-related plasma parameters showed differences between sexes, and obesity was associated with increased values, especially leptin (500% in females and 273% in males) and insulin (150% in both females and males), as compared with lean mice. Our results indicate that lean mice display behavioral and endocrine differences between sexes, and obesity affects the parameters tested in a sex-dependent manner. The aforementioned leads us to propose N. alstoni, studied in captivity, could be an interesting model for the study of sex differences in the effects of obesity.

Barx2 and Fgf10 regulate ocular glands branching morphogenesis by controlling extracellular matrix remodeling

The lacrimal gland (LG) develops through branching morphogenesis and produces secretions, including tears, that lubricate and protect the ocular surface. Despite the prevalence of LG disorders such as dry eye, relatively little is known about the regulation of LG development. In this study, we show that the homeobox transcription factor Barx2 is highly expressed in conjunctival epithelium, eyelids and ocular [lacrimal, harderian (HG), and meibomian (MG)] glands and is necessary for normal ocular gland and eyelid development. Barx2(-/-) mice show defective LG morphogenesis, absence of the HG, and defects in MG and eyelid fusion. Ex vivo antisense assays confirm the requirement for Barx2 in LG bud elongation and branching. Gene expression profiles reveal decreased expression of several adhesion and matrix remodeling molecules in Barx2(-/-) LGs. In culture, Barx2 regulates expression of matrix metalloproteinases (MMPs) and epithelial cell migration through the extracellular matrix. Fibroblast growth factors are crucial regulators of LG development and we show that Barx2 is required for Fgf10-induced LG bud elongation and that both Barx2 and Fgf10 cooperate in the regulation of MMPs. Together, these data suggest a mechanism for the effects of loss of Barx2 on ocular gland development. Intriguingly, salivary glands that also express a high level of Barx2 develop normally in Barx2(-/-) mice and do not show altered levels of MMPs. Thus, the function of Barx2 is specific to ocular gland development. Based on our data, we propose a functional network involving Barx2, Fgf10 and MMPs that plays an essential role in regulating branching morphogenesis of the ocular glands.

Histomorphology of the Harderian gland in the Angora rabbit

This study was aimed to demonstrate the morphological and histochemical properties of the Harderian gland in the Angora rabbit. Ten healthy adult Angora rabbits obtained from private breeders constituted the material of the study. The Harderian gland, which is composed of the pink and white lobes, consists of cells that produce a secretion of lipid character. The pink lobe contained type I cells with large lipid vacuoles. Cells with small lipid vacuoles (type II) were found in the white lobe. Type III cells containing both large and small lipid vacuoles were not observed. While type I cells reacted strongly to staining with Oil red O, type II cells reacted weakly to this stain. The number of plasma cells was greater in the white lobe when compared to the pink lobe. The apical granules within the epithelial cells lining the intralobular and inter-lobular excretory ducts of the gland were positive for periodic acid-Schiff (PAS), periodic acid-Schiff/alcian blue (PAS/AB), alcian blue (AB) and performic acid/alcian blue (PA/AB). Electron microscopic examination revealed that type I cells contain large electron-light lipid vacuoles and an eccentric heterochromatic nucleus, due to the presence of these vacuoles. The cells, which were connected by tight junctions, possessed apically located microfolds. The nucleus of type II cells was situated basally and had an oval shape. Type II cells had apical microvilli-like cytoplasmic protrusions, longer than those of type I cells. Oval shaped myoepithelial cells were observed between the glandular epithelial cells and their basal lamina. The epithelium lining the excretory ducts of the gland contained two types of granules, which were dark and lightly coloured. Histochemical and ultrastructural examinations revealed no difference in the structure of the Harderian gland between female and male Angora rabbits.