REGIONAL DISTRIBUTION OF NEUROPEPTIDE-Y Y2 RECEPTOR MESSENGER-RNA IN THE HUMAN POST-MORTEM BRAIN

The neuropeptide Y Y2 receptor is one of six receptor subtypes mediati ng the multiform physiological actions of neuropeptide Y. The Y2 recep tor has been demonstrated to be the most predominant receptor subtype in the human brain and appears to be involved in many neuropeptide Y a ctions, such as the regulation of locomotor activity, cardiovascular f unctions, memory processing, circadian rhythms and release of other ne urotransmitters. We have recently demonstrated the widespread and abun dant distribution of neuropeptide Y Y1 receptor messenger RNA in the h uman cerebral cortex (different laminar patterns within distinct corti cal regions), hippocampal dentate gyrus and striatum. To assess a poss ible differential distribution of Y1 and Y2 receptor messenger RNAs, t he regional expression of neuropeptide Y Y2 messenger RNA-containing c ells in the human brain was analysed, in particular within the cerebra l cortex and striatum. In situ hybridization experiments revealed the localization of the Y2 messenger RNA signal throughout all cortical re gions, with the highest intensity per cell apparent in lamina TV, with the exception of the striate cortex, which showed an intense labellin g primarily in layer VI. The striatum expressed low to undetectable le vels of the Y2 receptor messenger RNA. The dentate gyrus and the CA2 r egion presented the highest hybridization signals, while a very weak Y 2 messenger RNA expression was found in the CA1 region and subiculum. Positive Y2 messenger RNA hybridization signals were also detected in the lateral geniculate nucleus, amygdala, substantia nigra, hypothalam us, cerebellum and choroid plexus. These results demonstrate the wides pread distribution of neuropeptide Y Y2 receptor messenger RNA in the human brain, with a pattern of expression distinct from the Y1 subtype , suggesting that these two receptor subtypes may mediate different ne uropeptide Y functions in the human brain, mainly through actions on d ifferent neuronal systems. (C) 1998 IBRO. Published by Elsevier Scienc e Ltd.