Increase in excitability of hippocampal neurons during novelty-induced hyperlocomotion in dopamine-deficient mice

Dopamine is involved in many important brain functions, including voluntary motor movement. Dysfunction of the dopaminergic system can induce motor impairments, including Parkinson's disease. We previously found that dopamine-deficient (DD) mice became hyperactive in a novel environment 72 h af...

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Bibliographic Details
Published in:Molecular brain 2020-09, Vol.13 (1), p.126-126, Article 126
Main Authors: Fujita, Masayo, Ochiai, Yukiko, Takeda, Taishi-Clark, Hagino, Yoko, Kobayashi, Kazuto, Ikeda, Kazutaka
Format: Article
Language:English
Subjects:
Animal memory
Brain
Dentate gyrus
Dihydroxyphenylalanine
Dopamine
Dopamine receptors
Excitability
Hippocampus
Hyperactivity
Immunohistochemistry
Injection
Levodopa
Micro Report
Movement disorders
Neurodegenerative diseases
Neurons
Neurophysiology
Parkinson's disease
Phenols (Class of compounds)
Rodents
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Summary:Dopamine is involved in many important brain functions, including voluntary motor movement. Dysfunction of the dopaminergic system can induce motor impairments, including Parkinson's disease. We previously found that dopamine-deficient (DD) mice became hyperactive in a novel environment 72 h after the last injection of L-3,4-dihydroxyphenylalanine (L-DOPA) when dopamine was almost completely depleted. In the present study, we investigated neuronal activity in hippocampal subregions during hyperactivity by measuring Fos expression levels using immunohistochemistry. Dopamine-deficient mice were maintained on daily intraperitoneal injections of 50 mg/kg L-DOPA. Seventy-two hours after the last L-DOPA injection, DD mice were exposed to a novel environment for 1, 2, or 4 h, and then brains were collected. In wildtype mice, the number of Fos-immunopositive neurons significantly increased in the hippocampal CA1 region after 1 h of exposure to the novel environment and then decreased. In DD mice, the number of Fos-immunopositive neurons gradually increased and then significantly increased after 4 h of exposure to the novel environment. The number of Fos-immunopositive neurons also significantly increased in the CA3 region and dentate gyrus in DD mice after 4 h of exposure to the novel environment. These results indicate that the delayed and prolonged excitation of hippocampal neurons in the CA1, CA3, and dentate gyrus that is caused by dopamine depletion might be involved in hyperactivity in DD mice.
ISSN:1756-6606
1756-6606
DOI:10.1186/s13041-020-00664-8