Biogenic Amine and Corticotrophin-Releasing Factor Concentrations in Hypothalamic Paraventricular Nucleus and Biogenic Amine Levels in the Median Eminence of Normal Dogs, Chronic Dexamethasone-Treated Dogs, and Dogs with Naturally-Occurring Pituitary-Dependent Hyperadrenocorticism (Canine Cushing's Disease)

We measured dopamine, norepinephrine, serotonin and epinephrine concentrations in the paraventricular nucleus and median eminence, and corticotrophin-releasing factor levels in the paraventricular nucleus. Tissue was isolated by micropunch technique from hypothalami of normal dogs, dogs treated for one week with dexamethasone (1 mg/kg/day) and dogs with spontaneous pituitary-dependent hyperadrenocorticism. Concentrations of corticotrophin-releasing factor and most of the neurotransmitters were found to be similar between our three groups of dogs. However, we found the mean dopamine concentration in the median eminence tissue to be significantly decreased in dogs with Cushing's disease and in steroid-treated dogs. Epinephrine levels were elevated in the hypothalamic paraventricular nucleus of steroid-treated dogs.