EXPRESSION OF THE NEUROPEPTIDE-Y Y-1 RECEPTOR MESSENGER-RNA IN THE HUMAN BRAIN - AN IN-SITU HYBRIDIZATION STUDY

USING cRNA in situ hybridization, the regional distribution of mRNA en coding the human Y-1 receptor was investigated in the normal human bra in and compared with the autoradiographic distribution of putative Y-1 /[I-125][Leu(31),Pro(34)]PYY binding sites. Surprisingly, relatively h igh levels of Y-1 receptor mRNA, distributed in a ty laminar fashion, were detected in the frontal and temporal cortices; laminae I, IV and VI were particularly enriched. The claustrum and nucleus of the medial geniculate body also revealed high levels of Y-1 receptor mRNA signal s. Moderate levels of specific hybridization were detected in the caud ate nucleus, putamen, nucleus accumbens, amygdaloid nuclei, and arcuat e and paraventricular nuclei of the hypothalamus. In all these regions , only very low levels of specific [I-125][Leu(31),Pro(34)]PYY binding were detected with the exception of the dentate gyrus of the hippocam pal formation which expressed rather high levels of both the Y-1 recep tor mRNA and its translated protein. Accordingly, the human brain can express the Y-1 receptor mRNA but this may not necessarily translate i nto a functional receptor as revealed by low specific binding levels o bserved in most regions.