Release of GABA following a single whisker stimulation in the adjacent barrels of rat somatosensory cortex.
The somatosensory cortex of rodents contains discrete groups of neurons in layer IV, called barrels, which are related in a one-to-one fashion to individual vibrissae. In order to examine the effect of a single vibrissa stimulation on the release of GABA in the barrel cortex, GABA was measured by brain microdialysis in the barrel cortex of anesthetized rats. The basal level of endogenous GABA release was 0.15 +/- 0.05 pmol/30 microliters dialysate (n = 15). Stimulation of a single vibrissa gave rise to a marked increase in GABA release above the basal level (80 +/- 56% of basal level, n = 8). Effects were limited to a single barrel representing the stimulated single vibrissa. The stimulus-evoked GABA release was completely suppressed by 10 microM TTX, while the basal release of GABA was not affected by TTX. Vibrissa stimulation often caused a significant decrease in the basal level of GABA in the neighboring barrel. These results suggest that the release of GABA evoked by a single vibrissa stimulation is regulated by an inter-barrel mechanism in the rat barrel cortex.
Shirokawa
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T
Department of Physiology, Akita University School of Medicine, Japan.
Ogawa
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T
D000818:Animals; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid