每週一篇
GABAA receptor-mediated signaling alters the structure of
spontaneous activity in developing retina
這是2007 neuroscience 的文章
summery:
Ambient GABA modulates firing patterns in adult neural circuits by
tonically activating extrasynaptic GABAA receptors. Here, we demonstrate
that during a developmental period when activation of GABAa receptors causes
membrane depolarization, tonic activation of GABAa receptors blocks all
spontaneous activity recorded in retinal ganglion cells(RGCs) and starburst
amacrine cells(SACs).
Bath application of the GABAa receptor agonist muscimol blocked spontaneous
correlated increases in intracellular calcium concertration and compound
postsynaptic currents in RGCs associated with retinal waves. In addition,
GABAa receptor agonists activated a tonic current in RGCs that significantly
reduced their excitability.
Using a transgenic mouse in which green fluorescent protein is expressed under
the metabotropic glutamate receptor subtype 2 promoter to target recordings
from SACs, we found that GABAa receptor agonists blocked componund postsynap-
tic currents and also activated a tonic current. GABAa receptor antagonists
reduced the holding current on SACs but not RGCs, indicating that ambient
levels of GABA tonically activate GABAa receptors in SACs. GABAa receptor
antagonists did not block retinal waves but ded alter the frepuency and
correlation structure of spontaneous RGC firing. Interestingly, the drug amino-
phylline, a general adenosine receptor antagonist used to block retinal waved,
induced a tonic GABAa receptor antagonist-sensitive current receptors.
These findings have implications for how various neuroactive drugs and neuroh-
ormones known to modulate extrasynaptic GABAa receptors may influence spontan-
eous firing patterns that are critical for the establishment of adult neural
circuits.
好長阿~~~
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