In vivo evaluation of ₂-adrenoceptors in cats with idiopathic cystitis

203 D affecting the lower portion of the urinary tract of cats are characterized by variable combinations of stranguria, hematuria, urinations in inappropriate locations (periuria), and pollakiuria. There are several differential diagnoses for these clinical signs, including urolithiasis, urinary tract infections, and primary behavioral abnormalities. When no underlying cause for these clinical signs can be found, a diagnosis of FIC is often made. The etiology of this disease is unknown, and it appears to affect male and female cats equally. The clinical signs of FIC wax and wane and are often reported by owners to be exacerbated by stressful circumstances. Chronic stress from internal and external sources can increase tyrosine hydroxylase activity, the rate-limiting step in catecholamine synthesis, in the LC with accompanying increases in autonomic outflow. Increased tyrosine hydroxylase immunoreactivity in the LC of cats with FIC has been reported. Increased plasma catecholamine concentrations, including dihydroxyphenylalanine, norepinephrine, and dihyroxyphenylglycol, in cats with FIC, compared with healthy cats, also have been reported. In vivo evaluation of α2-adrenoceptors in cats with idiopathic cystitis