Cellular expression of P2Y and β-AR receptor mRNAs and proteins in freshly isolated astrocytes and tissue sections from the CA1 region of P8–12 rat hippocampus

Abstract

Although almost all GFAP(+) cells in primary astrocyte cultures show functional β-adrenergic (β-AR) and metabotropic purinergic (P2Y) receptors, the fewer studies on astrocytes in situ have shown that a much smaller proportion express these same receptor-mediated activities. Here we show, by multiplex single cell RT-PCR, that 44% of freshly isolated, GFAP(+) astrocytes (FIAs) from the CA1 of P8–12 rat hippocampus always co-express β-adrenergic receptor mRNA subtypes with metabotropic ATP receptor mRNA subtypes (P2Y1, P2Y2 or P2Y4). We also found that β2 mRNA was the dominant β-AR subtype expressed. P2Y1 mRNA always co-expresses with either one or two subtypes of P2U-like receptor (P2Y2 or P2Y4) mRNAs. Immunocytochemical studies showed a similar percentage of all FIAs expressed β-AR and P2Y1 protein (54% and 52%, respectively), as for the mRNAs (46% and 65%, respectively). The staining of hippocampal sections for β-AR or P2Y1 receptor plus GFAP shows that there are quite numerous, scattered star-shaped GFAP(+) astrocytes in the CA1 region of P9–10 rat hippocampus that stained positive for either of these receptors. These data show that astrocytes in situ express, and to a large extent likely co-express, β-AR and P2Y receptors.