Correlation of mast cells with spindle cell hyperplasia in the adrenal cortex of IQI/Jic mice

Androgen Receptor Is Dispensable for X-Zone Regression in the Female Adrenal but Regulates Post-Partum Corticosterone Levels and Protects Cortex Integrity

Adrenal androgens are fundamental mediators of ovarian folliculogenesis, embryonic implantation, and breast development. Although adrenal androgen function in target tissues are well characterized, there is little research covering the role of androgen-signaling within the adrenal itself. Adrenal glands express AR which is essential for the regression of the X-zone in male mice. Female mice also undergo X-zone regression during their first pregnancy, however whether this is also controlled by AR signaling is unknown. To understand the role of the androgen receptor (AR) in the female adrenal, we utilized a Cyp11a1-Cre to specifically ablate AR from the mouse adrenal cortex. Results show that AR-signaling is dispensable for adrenal gland development in females, and for X-zone regression during pregnancy, but is required to suppress elevation of corticosterone levels post-partum. Additionally, following disruption to adrenal AR, aberrant spindle cell development is observed in young adult females. These results demonstrate sexually dimorphic regulation of the adrenal X-zone by AR and point to dysfunctional adrenal androgen signaling as a possible mechanism in the early development of adrenal spindle cell hyperplasia.

High Background Incidence of Spontaneous Subcapsular Adrenal Gland Hyperplasia of Tg.rasH2 Mice Used in 26-week Carcinogenicity Studies

The Tg.rasH2 model was accepted by regulatory agencies worldwide for 26-week carcinogenicity assays as an alternative to the standard 2-year assays in conventional mice in 2003. Several references documenting spontaneous nonneoplastic findings and incidences of spontaneous tumors in the Tg.rasH2 mice have been published. The purpose of this publication is to add adrenal gland subcapsular hyperplasia to the database pertaining to spontaneous lesions noted in Tg.rasH2 mice, review physiology related to this finding, and discuss its significance. The incidence of spontaneous subcapsular adrenal gland hyperplasia was determined in control Tg.rasH2 mice from nine 26-week carcinogenicity studies carried out within the last 5 years at two contract research organizations. Incidence of this finding ranged from 56% to 79% in males and 88% to 100% in females, with an incidence average of 62% in males and 93% in females. Adrenal gland subcapsular hyperplasia is a common finding in male and female Tg.rasH2 mice that did not progress to neoplasia in Tg.rasH2 mice. In general, it tends to be more frequent and severe in females in comparison to males.

The Environmental Pollutant Tributyltin Chloride Disrupts the Hypothalamic-Pituitary-Adrenal Axis at Different Levels in Female Rats

Tributyltin chloride (TBT) is an environmental contaminant that is used as a biocide in antifouling paints. TBT has been shown to induce endocrine-disrupting effects. However, studies evaluating the effects of TBT on the hypothalamus-pituitary-adrenal (HPA) axis are especially rare. The current study demonstrates that exposure to TBT is critically responsible for the improper function of the mammalian HPA axis as well as the development of abnormal morphophysiology in the pituitary and adrenal glands. Female rats were treated with TBT, and their HPA axis morphophysiology was assessed. High CRH and low ACTH expression and high plasma corticosterone levels were detected in TBT rats. In addition, TBT leads to an increased in the inducible nitric oxide synthase protein expression in the hypothalamus of TBT rats. Morphophysiological abnormalities, including increases in inflammation, a disrupted cellular redox balance, apoptosis, and collagen deposition in the pituitary and adrenal glands, were observed in TBT rats. Increases in adiposity and peroxisome proliferator-activated receptor-γ protein expression in the adrenal gland were observed in TBT rats. Together, these data provide in vivo evidence that TBT leads to functional dissociation between CRH, ACTH, and costicosterone, which could be associated an inflammation and increased of inducible nitric oxide synthase expression in hypothalamus. Thus, TBT exerts toxic effects at different levels on the HPA axis function.

Electron microscopic study of subcapsular cell hyperplasia in the adrenal glands of IQI/Jic mice

Hyperplastic cells in subcapsular cell hyperplasia (SCH) lesion in adrenal glands of female IQI/Jic mice were examined by electron microscopy. These cells were small and polygonal, and had irregular nuclei, elongated mitochondria with lamellar cristae and dense lipid droplets. While these cells showed different features, some of them had desmosomes and basement membranes, and a few round mitochondria with tubular cristae as endocrine cells. These findings suggest that hyperplastic cells in SCH lesions might originate from endocrine blastemic cells.

Picryl chloride-induced allergic dermatitis in IQI/Jic female mice

IQI/Jic (IQI) mice are an ICR-derived inbred strain developed in Japan, and it is known that aged females of this strain develop allergic dermatitis of spontaneous nature. In the present study, young IQI female mice which were sensitized with picryl chloride (PCL) to the shaved skin of abdomen and then topically applied with PCL to the ear at 4, 11, 18 and 25 days after the sensitization were examined. The ear swelling response increased rapidly after the 1st application, peaked after the 2nd one, and then gradually decreased. Histopathologically, edema with inflammatory cell infiltration developed after the 1st application and progressed after the 2nd one. The number of mast cells, CD4-positive cells and MHC class II-positive cells became prominent accompanied with epidermal thickening and dermal fibroplasia after the 4th application when clear elevation of total serum IgE levels was observed in many mice. Compared with the dermatitis induced in the same way in BALB/c female mice, the nature was similar with each other but the degree was obviously severer in IQI female mice. IQI female mice are considered to be a useful laboratory animal for the investigation of allergic dermatitis.

Expression of cytokines and proteases in mast cells in the lesion of subcapsular cell hyperplasia in mouse adrenal glands

To examine the possible roles of mast cells in the pathogenesis of subcapsular cell hyperplasia (SCH) in the adrenal glands of mice, we investigated the expression of certain cytokines, including stem cell factor (SCF), tumor necrosis factor-alpha (TNF-alpha), nerve growth factor (NGF), and basic fibroblast growth factor (bFGF), and mast cell-specific proteases, such as mouse mast cell protease (mMCP)-2 and mMCP-7. The mRNAs of c-kit (SCF receptor), bFGF, TNF-alpha, mMCP-2, and mMCP-7 were expressed in both the adrenal glands and the mouse bone marrow-derived mast cells (mBMMCs). Immunoreactivities for cytokines (SCF, NGF, TNF-alpha) and proteases (mMCP-2, mMCP-7) were exclusively located in the mast cells in SCH lesions. The immature mBMMCs did not express the mRNAs of SCF and NGF, whereas the mast cells in the SCH lesions showed the expression of SCF and NGF. These findings suggest that SCH may provide a favorable microenvironment for functional maturation of mast cells to produce SCF and NGF, and the mast cells in SCH lesions synthesize SCF and NGF and may, in part, use them in autocrine fashion for their survival and differentiation. Therefore, mast cells may contribute to SCH pathogenesis by producing a range of multifunctional cytokines and proteases.

Subcapsular cell hyperplasia and mast cell infiltration in the adrenal cortex of mice: comparative study in 7 inbred strains

Subcapsular cell hyperplasia (SCH) in the adrenal cortex of aged mice (13-15 months old) was frequent in both sexes of BALB/c, C3H/He, DBA/2J and IQI/Jic mice and in the females of A/J and C57BL/6, although the incidence and severity of SCH were considerably different among mouse strains. Mast cells were closely associated with SCH in the A/J, BALB/c, C57BL/6, DBA/2J and IQI/Jic mice, but not in the C3H/He strain. Compared with other strains, IQI/Jic mice had a significantly larger number of mast cells in the adrenal glands. Our findings suggest that mast cells may participate in the development of SCH, and IQI/Jic would be suitable for studying the pathogenesis of SCH and the role of mast cells in this lesion.