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Metabotropic glutamate receptors in acutely isolated hippocampal astrocytes: Developmental changes of mGluR5 mRNA and functional expression
Author(s) -
Cai Zhaohui,
Schools Gary P.,
Kimelberg Harold K.
Publication year - 2000
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(20000101)29:1<70::aid-glia7>3.0.co;2-v
Subject(s) - metabotropic glutamate receptor 5 , biology , glutamate receptor , astrocyte , glial fibrillary acidic protein , metabotropic glutamate receptor , hippocampal formation , endocrinology , metabotropic glutamate receptor 6 , metabotropic receptor , receptor , medicine , metabotropic glutamate receptor 1 , neuroscience , microbiology and biotechnology , biochemistry , central nervous system , immunohistochemistry , immunology
We previously found that 82% of glial fibrillary acidic protein (GFAP)‐positive hippocampal astrocytes acutely isolated from P1–10 rats responded to glutamate (Glu) with transient intracellular calcium increases via activation of a Group I metabotropic glutamate receptor (mGluR). Fewer cells responded to ATP and none to serotonin (5‐HT). In this study we asked the question whether hippocampal astrocytes in older animals retain this relative pattern of expression. We have found that 77% of GFAP (+) cells from P11–20 rats responded to 50 μM Glu, 43% to ATP, and none to 5‐HT. Thirty‐three percent of GFAP (+) cells from P25–35 rats responded to Glu, 12% to ATP and 3% to 5‐HT. In the case of the responses to Glu, pharmacological characterization and single‐cell RT‐PCR data confirmed that these responses were mediated by the mGluR5 subtype of group I mGluRs. Also, fewer (36%) GFAP mRNA (+) cells from P25–35 rats expressed detectable mGluR5 mRNA than those from P11–20 rats (77%). This number essentially corresponds to the number of GFAP(+) showing a Ca 2+ response to Glu. Both mGluR5a and b were expressed with equal frequency in cells from P11–20 rats, but the b form predominated in cells from older animals. Overall, our studies show that expression of mGluR5 in hippocampal astrocytes decreases with increasing age and the “a” splice variant declines to a greater extent than the “b” splice variant, corresponding to the developmental changes shown in total tissue for mGluR5. GLIA 29:70–80, 2000. © 2000 Wiley‐Liss, Inc.