Technical Aspects in the Study of Pathologic Lesions in the Hypothalamus of the Rat. In: Jones TC, Mohr U, Hunt RD, Capen CC, editors. Endocrine System. Berlin: Springer Berlin Heidelberg; 1983. pp. 311-6. [DOI: 10.1007/978-3-642-96720-7_63]

Pathologic effects of butylated triphenyl phosphate-based hydraulic fluid and tricresyl phosphate on the adrenal gland, ovary, and testis in the Fischer-344 rat

Triaryl phosphates including tricresyl phosphate (TCP) and butylated triphenyl phosphates (BTPs) are used in the commercial manufacture of plastics, lubricants, and hydraulic fluids. Recent reports implicate these compounds as endocrine and reproductive toxicants in rodents. The objectives of this study were to develop and characterize a rat model to investigate the mechanism(s) of toxicity of triaryl phosphate-based hydraulic fluids and to elucidate potential mechanistic pathways of toxicity through studies of structural/functional relationships. Groups of male and female rats received daily oral doses of either sesame oil alone or 1.7 g/kg of BTP or 0.4 g/kg TCP in sesame oil vehicle or 2.8 g/kg neat BTP for 20, 40, and 60 days. Light microscopic, morphometric, ultrastructural, and histochemical studies revealed hypertrophy and cholesteryl lipidosis of adrenocortical (both sexes) and ovarian interstitial cells that were progressive with duration of exposure. Minimal degeneration was observed in the adrenal cortex and ovary. TCP caused the most severe lesions in both the adrenal gland and ovary, but the morphologic and histochemical changes produced were similar for both compounds, suggesting a common mechanism of toxicity. Decreased testicular weight and degeneration of seminiferous tubules were detected only in TCP-treated rats. The Fischer-344 rat model using TCP and BTP administered by gavage is a valuable system to study mechanisms of endocrine and reproductive toxicity induced by triaryl phosphate-based hydraulic fluids.

Equine pituitary adenoma: a functional and morphological study

Clinico-pathological correlations in horses with pituitary adenomas are poorly understood. This paper describes the functional and morphological features of five cases of equine pituitary adenoma and of a case of multinodular pituitary hyperplasia. New findings reported include immunoreactivity for beta-lipotropin (beta-LPH), beta-melanocyte-stimulating hormone (beta-MSH), gamma 3-MSH, prolactin (PRL), and follicle-stimulating hormone (FSH) in neoplastic cells of the pituitary adenoma; and, in the multinodular hyperplasia, beta-LPH, beta-endorphin (beta-END), alpha-MSH, beta-MSH, gamma 3-MSH and FSH immunoreactivity. It is suggested that the equine pituitary syndrome does not correspond to human Cushing's disease, as generally accepted, but is related to the overproduction of several pro-opiomelanocortin (POMC)-derived peptides by the cells of the tumour or hyperplastic nodules.

Basement membrane of hypothalamus and cortex capillaries from normotensive and spontaneously hypertensive rats with streptozotocin-induced diabetes

Basement membrane (BM) thickness of hypothalamic arcuate nucleus capillaries was measured in normotensive (WKY) and hypertensive (SHR) rats 4 and 8 months after streptozotocin or saline injection. Three groups were studied: controls (C), diabetics (D), and animals with impaired glucose tolerance (L). For comparison, BM thickness of cortical capillaries of an occipital and a frontal area was measured in three different layers starting from the pial surface. Independently from strain, hypothalamic capillary BM was thicker in older than in younger animals. At both 4 and 8 months, BM thickness was lowest in C, highest in D, and intermediate (between C and D) in L. Hypertension combined with diabetes did not further increase BM thickness. In both C and D no difference was found between the two cortical areas. The BM thickness of C increased from the superficial to the deep layer. In C hypertension induced BM thickening in the superficial frontal and the deep occipital layer. In the intermediate and the deep layer of the frontal area BM was thicker in WKY-D than in WKY-C. In every layer BM was thicker in SHR-D than in corresponding controls. Hypertension combined with diabetes enhanced BM thickening in the intermediate and the deep layer of the frontal and in the intermediate layer of the occipital area. Degenerative changes occurred in hypothalamic and cortical pericytes. These changes were more frequent in hypertensive than in normotensive animals. In conclusion, a microangiopathy characterized by BM thickening and pericytic degeneration occurs in the brain of diabetic animals. Its intensity and enhancement by a concomitant hypertension vary from hypothalamus to cortex.