Altered hippocampal circuit function in C3H alpha7 null mutant heterozygous mice

Area of Science:

• Neuroscience
• Neuropharmacology

Background:

• The alpha7 nicotinic receptor is prevalent in the hippocampus.
• It is believed to regulate the release of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter.
• This regulation is hypothesized to be crucial for hippocampal auditory gating, which controls responses to repetitive auditory stimuli.

Purpose of the Study:

• To investigate the role of hippocampal alpha7 nicotinic receptors in auditory gating.
• To overcome the limitations of inter-strain comparisons by using genetically modified mice on a consistent background.

Main Methods:

• Comparison of hippocampal alpha-bungarotoxin binding and auditory gating in C3H wild type and C3H alpha7 receptor null mutant heterozygous mice.
• Assessment of CA3 pyramidal neuron responsivity.

Main Results:

• C3H alpha7 heterozygous mice showed reduced hippocampal alpha7 receptor levels.
• These mice also exhibited abnormal hippocampal auditory gating.
• An overall increase in CA3 pyramidal neuron responsivity was noted in heterozygous mice compared to wild type.

Conclusions:

• Decreasing hippocampal alpha7 nicotinic receptor density significantly alters hippocampal circuit function.
• Alpha7 nicotinic receptors play a key role in modulating hippocampal inhibitory neurotransmission and sensory gating.