PENETRATION OF PHOSPHOROTHIOATE OLIGODEOXYNUCLEOTIDES INTO RAINBOW-TROUT BRAIN IN-VIVO - A TECHNIQUE FOR CHRONIC INFUSION OF SUBSTANCES INTO THE BRAIN OF FREE-LIVING ADULT FISH

This paper describes a method for infusing chronically substances into the cranial cavity of free-living rainbow trout Oncorhynchus mykiss f or several weeks. The efficacy of the method was established by examin ing the penetration of radioactively labelled phosphorothioate oligode oxynucleotides and a blue-coloured dye, xylene cyanole, into brain tis sue. No problems with pump patency were encountered, and the contents of the pump diffused consistently throughout the brain ventricular sys tem, including the anterior lateral ventricles of the olfactory lobes, the third ventricle under the optic tecta and into the hypothalamus, including the lateral ventricular recesses. Autoradiographic examinati on of frozen sections demonstrated variable penetration of labelled pr obe into brain interstitium to a depth of up to approximately 200 mu m . At the end of the experiment, >50% of radioactivity within brain tis sue was shown to be of similar size to intact, labelled oligodeoxynucl eotides. (C) 1997 The Fisheries Society of the British Isles.