Characteristics of glycine receptors expressed by embryonic rat brain mRNAs
AUTOR(ES)
García-Alcocer, Guadalupe
FONTE
The National Academy of Sciences
RESUMO
A study was made of glycine (Gly) and γ-aminobutyric acid (GABA) receptors expressed in Xenopus oocytes injected with rat mRNAs isolated from the encephalon, midbrain, and brainstem of 18-day-old rat embryos. In oocytes injected with encephalon, midbrain, or brainstem mRNAs, the Gly-current amplitudes (membrane current elicited by Gly; 1 mM Gly) were respectively 115 ± 35, 346 ± 28, and 389 ± 22 nA, whereas the GABA-currents (1 mM GABA) were all ≤40 nA. Moreover, the Gly-currents desensitized faster in oocytes injected with encephalon or brainstem mRNAs. The EC50 for Gly was 611 ± 77 μM for encephalon, 661 ± 28 μM for midbrain, and 506 ± 18 μM for brainstem mRNA-injected oocytes, and the corresponding Hill coefficients were all ≈2. Strychnine inhibited all of the Gly-currents, with an IC50 of 56 ± 3 nM for encephalon, 97 ± 4 nM for midbrain, and 72 ± 4 nM for brainstem mRNAs. During repetitive Gly applications, the Gly-currents were potentiated by 1.6-fold for encephalon, 2.1-fold for midbrain, and 1.3-fold for brainstem RNA-injected oocytes. Raising the extracellular Ca2+ concentration significantly increased the Gly-currents in oocytes injected with midbrain and brainstem mRNAs. Reverse transcription–PCR studies showed differences in the Gly receptor (GlyR) α-subunits expressed, whereas the β-subunit was present in all three types of mRNA. These results indicate differential expression of GlyR mRNAs in the brain areas examined, and these mRNAs lead to the expression of GlyRs that have different properties. The modulation of GlyRs by Ca2+ could play important functions during brain development.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=30216Documentos Relacionados
- Widespread expression of glycine receptor subunit mRNAs in the adult and developing rat brain.
- Expressional potency of mRNAs encoding receptors and voltage-activated channels in the postmortem rat brain.
- Discrimination of heterogenous mRNAs encoding strychnine-sensitive glycine receptors in Xenopus oocytes by antisense oligonucleotides.
- Regulation of three beta-tubulin mRNAs during rat brain development.
- Structural characterization of a heterogeneous family of rat brain mRNAs.