Gene expression analysis of Arc mRNA as a neuronal cell activity marker in the hippocampus and amygdala in two-way active avoidance test in rats

• Published in: Journal of pharmacological and toxicological methods 2017-11, Vol.88 (Pt 2), p.140-146
• Main Authors: Yasuno, Kyohei, Takahashi, Erika, Igarashi, Isao, Iguchi, Takuma, Tsuchiya, Yoshimi, Kai, Kiyonori, Mori, Kazuhiko
• Format: Article
• Language: English
• Subjects: Amygdala - drug effects; Amygdala - metabolism; Animals; Arc; Avoidance Learning - drug effects; Avoidance Learning - physiology; Benzazepines - pharmacology; Cytoskeletal Proteins - biosynthesis; Cytoskeletal Proteins - genetics; Fear - drug effects; Fear - physiology; Fos; Gene Expression; Genes, Immediate-Early - drug effects; Genes, Immediate-Early - physiology; Hippocampus - drug effects; Hippocampus - metabolism; Immediate early gene; Male; Muscarinic Antagonists - pharmacology; Nerve Tissue Proteins - biosynthesis; Nerve Tissue Proteins - genetics; Neurons - drug effects; Neurons - metabolism; Rat; Rats; Rats, Inbred F344; Rats, Sprague-Dawley; Receptors, Dopamine D1 - antagonists & inhibitors; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; SCH 23390; Scopolamine; Scopolamine Hydrobromide - pharmacology; Two-way active avoidance test
• ISSN: 1056-8719; 1873-488X
• DOI: 10.1016/j.vascn.2017.09.255

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. 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). 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. 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.