[Effect of bicuculline on first spike latency of the neurons in the inferior colliculus of mice].
OBJECTIVE
To evaluate the effect of bicuculline on the first spike latency of the neurons in the inferior colliculus of mice and investigate the role of GABA inhibition in sound signal processing of the neurons.


METHODS
In vivo extracellular recording was performed on the inferior colliculus of 13 BALB/c mice (4 to 5 weeks old) to record the neuronal response to pure tones. Bicuculline, a GABA-A receptor antagonist, was applied to the neurons iontophoretically through one channel in the three-barrel glass-pipettes. The first spike latency and other response properties of the characteristic frequency were recorded for analysis.


RESULTS
A total of 30 well-isolated single neurons were recorded. Increased spike counts characterized 96% of the neurons, with either increased (40%) or decreased (60%) latency of neuronal responses. Characteristic frequency alterations occurred in 50% of the neurons with increased spike latency, and the minimum threshold showed linear changes.


CONCLUSIONS
GABAergic inhibition may participate in the latency formation and increased frequency selectivity of mouse inferior colliculus neurons by lateral inhibition. The changes in the first spike latency can be indicative of the information integration in GABAergic neurons at the synaptic level.
Cong
Wen-dong
WD
Department of Physiology, Southern Medical University, Guangzhou 510515, China. gzcongwd@gmail.com
Xiao
Zhong-ju
ZJ
D000161:Acoustic Stimulation / Q000523:psychology; D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology*; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D007245:Inferior Colliculi / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009474:Neurons / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D018756:GABA Antagonists; D005680:gamma-Aminobutyric Acid; D001640:Bicuculline