Increase in Expression of Brain Serotonin Transporter and Monoamine Oxidase A Genes Induced by Repeated Experience of Social Defeats in Male Mice

M. L. Filipenko^1*, A. G. Beilina¹, O. V. Alekseyenko², V. V. Dolgov², and N. N. Kudryavtseva²

¹Institute of Bioorganic Chemistry, Siberian Division of the Russian Academy of Sciences, pr. Akademika Lavrentieva 8, Novosibirsk, 630090 Russia; fax: 3832-333-677; E-mail: max@niboch.nsc.ru

²Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Sciences, pr. Akademika Lavrentieva 10, Novosibirsk, 630090 Russia; fax: 3832-331-278; E-mail: natnik@bionet.nsc.ru

^* To whom correspondence should be addressed.

Received February 14, 2001; Revision received May 4, 2001

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Serotonin transporter and monoamine oxidase (MAO) A are involved in the inactivation of serotonin. The former is responsible for serotonin re-uptake from the synapse, whereas the latter catalyzes serotonin deamination in presynaptic terminals. Expression of serotonin transporter and MAO A genes was investigated in raphe nuclei of midbrain of CBA/Lac male mice with repeated experience of social victories or defeats in 10 daily aggressive confrontations. The amount of cDNA of these genes was evaluated using multiplex RT-PCR. Two independent experiments revealed that the defeated mice were characterized by significantly higher levels of serotonin transporter and MAO A mRNAs than the control and aggressive animals. Increased expression of MAO A and serotonin transporter genes is suggested to reflect the accelerated serotonin degradation in response to activation of the serotonergic system functioning induced by social stress. Significant positive correlation between MAO A and serotonin transporter mRNA levels suggests common pathways of regulation of transcriptional activity of these genes.

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KEY WORDS: gene expression, serotonin transporter, monoamine oxidase A, mouse, multiplex PCR, mRNA level

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