Immunohistochemical localization of the P2Y1purinergic receptor in Alzheimer's disease

The biological actions of extracellular nucleotides are mediated by two distinct classes of P2 receptor, P2X and P2Y. The G protein-coupled P2Y receptors comprise five mammalian subtypes, P2Y1-11.The P2Y1subtype is expressed abundantly throughout the human brain and is specifically localized to neuronal structures. In the present study, the distribution of the P2Y1receptor was investigated in Alzheimer's disease (AD) brains. In contrast to control human brain, the P2Y1receptor was localized to a number of characteristic AD structures such as neurofibrillary tangles, neuritic plaques and neuropil threads. Immunoblot analysis showed that this specific immunostaining observed over tangles was not a result of cross-reactivity between the anti-P2Y1antiserum and abnormal tau protein, the major constituent of tangles. The significance of this altered P2Y1cellular distribution in AD brains is at present unclear.