Immunohistochemical localisation of neuronal nitric oxide synthase in the rainbow trout kidney

The distribution of nitrergic nervous structures in the trout kidney was st udied by peroxidase-linked ABC immunostaining procedures using a polyclonal antibody raised against the neuronal isoform of nitric oxide synthase. The nitrergic plexus reaches the kidney along the vasculature, mainly running with the postcardinal vein where nitrergic fibres, microganglia like cellul ar clusters and isolated neurones were detected. The atubular head-kidney o nly showed isolated nitrergic fibres close to the: larger arteries. On the other hand, the collecting tubules, collecting ducts, large arteries and gl omerular arterioles of the tubular middle and posterior trunks were innerva ted by nitrergic fibres even though immunoreactive neurones were also obser ved in close apposition to some tubular elements and large arteries. These results suggest that, according to morphofunctional differences between the fish and mammalian kidneys, nitrergic neural structures may be involved in the control of particular renal functions in the rainbow trout. (C) 2001 E lsevier Science B.V. All rights reserved.