Regional distribution of nitric oxide synthase and NADPH-diaphorase activities in the central nervous system of teleosts

Neuronal nitric oxide synthase (nNOS) and NADPH-diaphorase activities were investigated in discrete areas of the central nervous system of goldfish an d brown trout. Both species showed a similar distribution pattern of nNOS a ctivity with regional differences in all examined areas. Telencephalon and hypothalamus showed the highest nNOS values, while in the goldfish cerebell um and its valvula nNOS was not detectable. In both species, NADPH-diaphora se activity showed a lower regional variability, compared to nNOS. The high est activity was measured in the olfactory bulbs where, conversely, low lev els of nNOS activity were present. The non close correspondence between NOS and NADPH-diaphorase activities confirms the discrepancies indicated by mo rphological data. Western blot analysis revealed the presence of a nNOS iso form of about 150 kDa mel. wt. corresponding to that of mammals. The patter n of nNOS expression in the considered brain regions of the goldfish and tr out was comparable to the levels of the nNOS activity. (C) 2001 Elsevier Sc ience B.V. All rights reserved.