HISTOAUTORADIOGRAPHIC DETECTION OF OXYTOCIN-BINDING AND VASOPRESSIN-BINDING SITES IN THE TELENCEPHALON OF THE RAT

Localization of oxytocin- and vasopressin-binding sites has so far bee n studied in the rat brain by means of film autoradiographs. The dispo sal of iodinated ligands with high specificity has allowed us to devel op histoautoradiography on emulsion-coated sections and to reinvestiga te on a microscopic scale the distribution of these sites in the telen cephalon (septum, striatopallidal system, amygdala and hippocampus). T his technique showed that oxytocin and vasopressin labelling presented distinct distributions and coincided with delimited zones, correspond ing to anatomical subdivisions defined on cytoarchitectural and immuno cytochemical bases. Vasopressin sites were seen in the dorsal and inte rmediate parts of the lateral septum and the juxtacapsular nucleus of the bed nucleus of the stria terminalis. Oxytocin sites were located i n the ventral and intermediate parts of the lateral septum, the oval a nd the principal nuclei of the bed nucleus of the stria terminalis and the septofimbrial nucleus. In the striatopallidal system, vasopressin sites were found in the accumbens nucleus and the fundus striati, whe reas oxytocin sites were in the accumbens nucleus, the head, and the p osterolateral parts of the caudate-putamen, the striatal cell bridges, and the olfactory tubercle. In the amygdala, vasopressin sites were n ot found, but oxytocin sites were located in the central, medial, and basomedial nuclei. In the hippocampus, vasopressin sites were located in the dentate gyrus (polymorph and molecular layers), and oxytocin si tes, in the subiculum (molecular and pyramidal layers) and in the fiel d CA1 of Ammon's horn (lacunosum moleculare and pyramidal layers). The localization of the binding sites at the microscopic level permitted us to reinvestigate whether or not correlation existed in a same area between innervation, electrophysiological effects, and presence of bin ding sites. (C) 1993 Wiley-Liss, Inc.