Metformin reduces insulin resistance and the tendency toward hyperglycaemia and dyslipidaemia in dogs with hyperadrenocorticism.

Hypercortisolism induces a state of insulin resistance that can occur concurrently with fasting hyperglycaemia, dyslipidaemia and diabetes mellitus. Metformin reduces hepatic glucose production and insulin resistance of the skeletal muscle and adipose tissue. The aim of this study was to evaluate the effects of metformin on the control of metabolic disorders of dogs with hyperadrenocorticism (HAC). Twenty-three dogs with HAC were randomly divided into two groups, consisting of a control group and a metformin group (10 mg metformin/kg/12 h). Both groups received the same treatment for HAC. At baseline and 3 months, blood glucose, total cholesterol, triglycerides and insulin concentrations, in addition to urinary cortisol:creatinine ratio, Homeostatic Model Assessment (HOMA) for insulin sensitivity and ß-cell function were measured. Dogs treated with metformin showed significantly reduced glycaemia, cholesterolaemia and triglyceridaemia. They also presented reduced hyperinsulinism and insulin resistance, as well as improved pancreatic ß-cell function. The implementation of metformin as an adjuvant therapy is effective for the normalisation of metabolic disorders of dogs with HAC.

Decrease of nitric oxide and increase in diastolic blood pressure are two events that affect renal function in dogs with pituitary dependent hyperadrenocorticism.

Hyperadrenocorticism is a frequent disease in dogs. The excess of circulating cortisol affects different organs and metabolic pathways, producing severe adverse effects that endanger the animal's life. Among these effects, hypertension and renal damage can be mentioned. A group of 20 dogs with pituitary dependent hyperadrenocorticism (PDH) and 12 control dogs were used to study the following parameters: cortisol and nitric oxide (NO nit/nit) concentrations, diastolic and systolic blood pressure, renal artery resistance index by Doppler ultrasound, the rate of glomerular filtration by radio-renogram excretion and the presence of proteins in urine. Dogs with PDH showed a significantly lower NO nit/nit (P<0.0001) than the controls and this correlated with high values of diastolic and systolic pressure (r = -0.87; P<0.0001 and r = -0.81; P<0.0001 respectively). Most dogs (80%) are hypertensive mainly due to an increase in diastolic pressure, which correlated positively with the UPC (r = 0.8; P<0.001) and negatively with the glomerular rate of filtration (r = -0.58; P=0.007). Systolic pressure only increased in 60% of the cases and did not correlate with the mentioned variables. In PDH the decrease of NO affects blood pressure. The diastolic pressure would seem to have the greatest impact on the kidneys, therefore its evaluation and control are important to avoid and/or control renal damage.

Overexpression of 11ß-hydroxysteroid dehydrogenase 1 in visceral adipose tissue and underexpression of endothelial nitric oxide synthase in the adrenal cortex of dogs with hyperadrenocorticism.

11ß-Hydroxysteroid dehydrogenase 1 (11ß-HSD1) is an enzyme that activates cortisone into cortisol in tissues. Alterations in this enzyme are related to the development of metabolic syndrome, obesity and hyperadrenocorticism (HAC). Endothelial nitric oxide synthase (eNOS) produces nitric oxide and is related to the regulation of adrenal steroidogenesis. The aim of the study was to evaluate 11ß-HSD1 and eNOS expression in dogs with HAC. Visceral adipose tissue samples were taken to evaluate 11ß-HSD1 expression by immunohistochemistry and western blotting. In parallel, adrenal gland samples were collected to evaluate eNOS expression by immunohistochemistry. 11ß-HSD1 expression was significantly higher in the adipocytes of dogs with HAC than in those of the control dogs. eNOS expression in the adrenal cortex (zona fasciculata) was significantly lower in the dogs with HAC than in the control dogs. 11ß-HSD1 overexpression and eNOS underexpression could play a role in the maintenance of hypercortisolism in dogs with HAC.

Addison disease and normocalcemic primary hyperparathyroidism in a dog with multiple endocrine neoplasia.

A 12-year old dog with a 9-year history of primary adrenal insufficiency was referred to the service for hyporexia, muscle weakness, polyuria and polydipsia. Ultrasound examination showed an unresectable mass in the left adrenal gland, with local vascular invasion, which prompted the euthanasia of the animal. Additionally, necropsy revealed a nodular lesion in the right adrenal gland and enlargement of one of the four parathyroid glands. Parathyroid hormone levels were elevated, but ionized and total calcium levels were normal. Histopathology supported the diagnosis of parathyroid chief cell adenoma and bilateral pheochromocytoma. Immunohistochemical staining was positive for synaptophysin, and negative for Melan-A and calretinin, which confirmed the diagnosis of pheochromocytoma. This case highlights an unusual presentation of multiple endocrine neoplasias within the context of primary adrenal insufficiency and normocalcemic primary hyperparathyroidism.

Síndrome de Cushing adrenal dependiente de hormona luteinizante / Luteinising hormone-dependent Cushing's syndrome

La hormona luteinizante (LH) y la gonadotropina coriónica humana (hCG) puede inducir esteroidogénesis, hiperplasia y tumorigénesis adrenal a través del estímulo sobre el receptor constitutivo de la LH (R-LHCG) en la corteza adrenal. Los mecanismos fisiopatológicos del síndrome de Cushing adrenal dependiente de LH (SCa-LH) no se han establecido plenamente, pero es reconocida la relación ontogénica adrenal-gonadal con mutua participación de diversos genes, factores de transcripción y enzimas esteroidogénicas como posible causa. El SCa-LH fue descrito en mujeres durante la gestación por el estímulo de hCG y en la posmenopausia ante el aumento de LH, así como en hurones luego de la gonadectomía quirúrgica.

Luteinising hormone (LH) and human chorionic gonadotropin (hCG) can induce steroidogenesis, hyperplasia, and adrenal tumorigenesis through the stimulus of the constitutive LH receptor (R-LHCG) within the adrenal cortex. The pathophysiological mechanisms of luteinising hormone-dependent Cushing's syndrome are not completely understood, but the ontogenic relationship between the adrenal cortex and the gonads, with mutual participation of different genes, transcription factors and steroidogenic enzymes cited as a possible cause, is well-recognised. SCa-LH has been described in pregnant women, as a result of hCG stimulus, and in post-menopausal women, due to increased levels of LH, as well as in ferrets after gonadectomy.