COLCHICINE DIFFERENTIALLY INDUCES THE EXPRESSIONS OF NITRIC-OXIDE SYNTHASES IN CENTRAL AND PERIPHERAL CATECHOLAMINERGIC NEURONS

This study was aimed at elucidating differences in nerve injury induce d expression of nitric oxide synthases (NOS) between the peripheral an d central catecholaminergic neurons. Colchicine was used to disrupt ch emically the neuronal cytoskeletal integrity. A marked increase in the expression of neuronal NOS-IR and NADPH-diaphorase activity, a marker of neuronal NOS (nNOS), was seen in distinct populations of postgangl ionic sympathetic neurons of the superior cervical ganglion after intr aganglionic colchicine injection. Similarly, immunoreactivity for the inducible form of NOS (iNOS) was induced in some sympathetic neuron so mata. However, this immunoreactivity did not coincide with nNOS-IR, In contrast to the sympathetic neurons, hypothalamic arcuate and periven tricular dopaminergic neurons did not show NOS-IR or NADPH-DA either i n intact animals or in animals treated with an intracerebroventricular injection of colchicine. Immunoreactivity for the inducible form of N OS revealed no neuronal staining in the hypothalamic neurons in either group, while a large number of glia-resembling cells around the third ventricle showed slight expression of iNOS-IR. The present results sh ow that expression of both neuronal and inducible forms of NOS may be induced by colchicine in some catecholaminergic neurons. It is suggest ed that these inductions are specific to certain catecholaminergic neu ronal systems, like the sympathetic neurons, rather than a general pro perty of catecholaminergic neurons. (C) 1998 Academic Press.