neuropeptide-y and linsidomine

To establish which type of nerves (parasympathetic, sympathetic or sensory) produce nitric oxide in the rat lower urinary tract, chemical denervation of primary afferents and sympathetic nerves was carried out by systemic treatment with capsaicin and 6-hydroxydopamine, respectively, followed by identification of neuronal nitric oxide synthase immunoreactivity. Functional in vitro studies were also performed to examine whether the synthesis and release of nitric oxide was affected following treatment with the respective neurotoxins. Nerve fibres immunoreactive for substance P and calcitonin gene-related peptide were found in control tissue, but could not be detected following capsaicin treatment. In comparison, nitric oxide synthase-immunoreactive fibres appeared to be unaffected by capsaicin treatment. Administration of 6-hydroxydopamine resulted in a complete disappearance of tyrosine hydroxylase-immunoreactive nerves, whereas nitric oxide synthase-containing nerve fibres did not appear to be affected by the treatment. In ultrastructural studies, nitric oxide synthase immunoreactivity, as studied by colloidal gold particles, was found in the axoplasm and not in association with intraneuronal structures or synaptic vesicles. Gold particles representing substance P immunoreactivity were seen as clusters associated with large granular vesicles. In consecutive sections of nerve fibres, substance P and nitric oxide synthase were not found in the same axon profile. In functional studies on urethral tissue, application of capsaicin (1 microM) produced a long-lasting relaxation. The nitric oxide synthase inhibitor NG-nitro-L-arginine (0.1 mM) had no effect on this response. Systemic treatment with capsaicin or 6-hydroxydopamine had no effect on nerve-evoked, nitric oxide-mediated relaxations. The data suggest that nitric oxide synthase-containing nerves in the rat lower urinary tract do not belong to nerve populations sensitive to either the sympathetic neurotoxin, 6-hydroxydopamine, or the sensory neurotoxin, capsaicin.

Topics: Acetylcholinesterase; Animals; Antibody Specificity; Arginine Vasopressin; Calcitonin Gene-Related Peptide; Capsaicin; Enzyme Inhibitors; Female; Gold Colloid; Microscopy, Electron; Molsidomine; Neurons, Afferent; Neuropeptide Y; Nitric Oxide Synthase; Nitroarginine; Oxidopamine; Rats; Rats, Sprague-Dawley; Substance P; Sympathectomy, Chemical; Sympathetic Fibers, Postganglionic; Sympatholytics; Tyrosine 3-Monooxygenase; Urethra; Urothelium; Vasoconstrictor Agents; Vasodilator Agents

Neuropeptide Y and nitric oxide (NO) synthase are colocalized in nervous tissues. We tested the hypothesis whether or not NO might be involved in the release of neuropeptide Y. Neuropeptide Y concentration in the supernatant of PC12 rat pheochromocytoma cells, shown to express NO synthase I by immunohistochemistry, rose threefold in a time- and dose-dependent manner following sodiumnitroprusside and 3-morpholinosydnonimine (SIN-1) incubation. Neuropeptide Y mRNA expression was induced by NO-donors as a function of incubation-time. Neuropeptide Y production rose fivefold with zaprinast, an inhibitor of the phosphodiesterase V and threefold with nerve growth factor (NGF). Combined application of zaprinast and NGF did not further increase neuropeptide Y production while combination of zaprinast and sodiumnitroprusside potentiated the NO effect on neuropeptide Y release. The data suggest that NO regulates neuropeptide Y secretion of PC12 pheochromocytoma cells on the mRNA level.

Topics: Animals; Blotting, Northern; Enzyme Inhibitors; Immunohistochemistry; Molsidomine; Nerve Growth Factors; Neuropeptide Y; Nitric Oxide; Nitric Oxide Synthase; Nitroprusside; PC12 Cells; Pheochromocytoma; Phosphodiesterase Inhibitors; Purinones; Radioimmunoassay; Rats; RNA; Sodium-Potassium-Exchanging ATPase