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

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.

Comparative study on picryl chloride (PCL)-induced contact dermatitis in female IQI/Jic and BALB/c mice

Ear skin responses to picryl chloride (PCL)-induced contact dermatitis were compared in detail between IQI/Jic mice developed in Japan and BALB/c mice often used for the investigation of contact dermatitis. PCL was applied to the left ear of each mouse 4 (1st), 11 (2nd), 18 (3rd) and 25 days (4th) after sensitization of the abdominal skin with PCL. Time course examinations were carried out on the ear swelling responses, total IgE levels, skin histology and immunohistochemistry for infiltrated cells after the 1st and 4th application. In IQI mice, the peak time of the ear swelling responses tended to shift from 24 h to 9 h with marked elevation of total IgE levels and marked increase of mast cells showing degranulation after the 4th application when CD8(+) cells as well as CD4(+) cells also prominently increased. In BALB/c mice, except for the total IgE levels and the number of mast cells, the degrees of ear swelling responses, histological changes and increase of CD4(+) and CD8(+) cells were much less severe. Female IQI mice are considered to be a useful mouse strain for further investigations on the role of CD4(+) and CD8(+) T cells in the pathogenesis of contact dermatitis.

The role of calretinin, inhibin, melan-A, BCL-2, and C-kit in differentiating adrenal cortical and medullary tumors: an immunohistochemical study

Morphologic distinction between adrenal cortical and medullary tumors can be difficult. Previous studies have shown inhibin, melan-A, and BCL-2 to be useful markers for adrenal cortical tumors. We have recently observed a high level of calretinin expression in normal adrenal cortex but not the medulla and therefore evaluated its diagnostic application for adrenal tumors in comparison with inhibin, melan-A, and BCL-2. C-kit is a transmembrane tyrosine kinase receptor. Immunodetection of c-kit expression has been recently used for tumor diagnosis, and c-kit-positive tumors can potentially benefit from kit kinase inhibitor treatment. Although c-kit expression was reported in adrenal medulla and pheochromocytoma, it has not been evaluated in adrenal cortical tumors. In this study, 28 adrenal cortical tumors (12 carcinomas, 16 adenomas), 20 pheochromocytomas, and 20 extraadrenal paragangliomas were evaluated for calretinin, inhibin, melan-A, BCL-2, and c-kit expression by standard immunohistochemical assays on paraffin sections. The percentage of immunoreactivity in adrenal cortical tumors was as follows: calretinin, 96%; melan-A, 89%; inhibin, 92%; BCL-2, 20%; and c-kit, 5%. Normal adrenal medulla did not stain for c-kit but was positive for BCL-2. Eighty-six percent of pheochromocytomas stained for BCL-2 and none for calretinin, with the exception of the ganglioneuromatous areas in composite pheochromocytomas (n = 5). Extraadrenal paragangliomas showed reactivity with calretinin in 25%, melan-A in 5%, inhibin in 16%, BCL-2 in 38%, and c-kit in 8% of the cases. Our results indicate that calretinin is the most sensitive among all the adrenal markers tested. Like melan-A and inhibin, calretinin is also a very specific marker in differentiating cortical from medullary adrenal tumors. In addition, calretinin can be used to confirm a composite pheochromocytoma. BCL-2 does not appear to be useful in differentiating adrenal cortical from medullary tumors. C-kit is not useful in the diagnosis of adrenal tumors, and kit kinase inhibitor might have a limited role in the treatment of adrenal tumors and paraganglioma because of the low frequency of c-kit expression in these tumors.