Related Experiment Video
Updated: Feb 22, 2026
In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons
Published on: January 5, 2013
Gene expression analysis of Arc mRNA as a neuronal cell activity marker in the hippocampus and amygdala in two-way
Kyohei Yasuno1, Erika Takahashi1, Isao Igarashi1
1Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan.
Introduction:
Immediate early genes are widely used as neuronal cell activity markers in neuroscience. The present study investigated the relationship between their expression and abnormality in context fear conditioning.
Methods:
The learning test (two-way active avoidance test) was conducted in male rats administered with nonselective muscarinic antagonist scopolamine or selective dopamine D1-like receptor antagonist SCH 23390 at a dose level of 2.0 or 0.1mg/kg, respectively, for 4days. Expression levels of Arc and Fos mRNA in the hippocampus and amygdala were also evaluated on the second day of dosing by fluorescent in situ hybridization (FISH) and reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR).
Results:
Scopolamine had no effect on avoidance rate, but decreased freezing in the two-way active avoidance test. SCH 23390 decreased avoidance rate and increased freezing. In FISH and RT-qPCR assays, scopolamine decreased Arc mRNA in the hippocampus and amygdala, whereas SCH 23390 increased Arc mRNA in the hippocampus. By contrast, scopolamine and SCH 23390 did not change Fos mRNA expression compared to Arc mRNA expression.
Discussion:
The results of the learning test indicated that scopolamine or SCH 23390 respectively inhibited fear or context conditioning in rats. Furthermore, alteration of the expression of Arc mRNA but not of Fos mRNA in the hippocampus and amygdala of the brain was suggested to be a sensitive neuronal cell activity marker to detect behavioral abnormality in the two-way active avoidance test.
