TITLE:
Reduction of serotonergic gene expression in the raphe nuclei of the midbrain under positive fighting experience in male mice
AUTHORS:
Dmitry A. Smagin, Ul’yana A. Boyarskikh, Natalya P. Bondar, Maxim L. Filipenko, Natalia N. Kudryavtseva
KEYWORDS:
Tph2; Sert; MaoA; Bdnf; Creb; mRNA; Repeated Aggression; Fighting Deprivation
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.4 No.10B,
October
8,
2013
ABSTRACT: The concept of a major inhibitory role of serotonin
in aggressive behavior is widely accepted by investigators. There was ample
evidence that a pharmacologically-induced increase in the serotonin activity
attenuates agonistic behavior in animals, and that the manipulations
inhibiting the brain serotonergic system can elicit aggressiveness in male
mice and rats. Repeated experience of aggression in daily agonistic
interactions has been shown to reduce serotonin activity in brain of
victorious male mice. The study aimed to analyze expression of the serotonergic
genes -Tph2, Sert, Maoa and Htr1a, as
well as the Bdnf and Creb genes in the midbrain raphe nuclei
of male mice with positive fighting experience in daily encounters and male
mice with the same track record of aggression followed by two-week no-fight
period. It has been shown that mRNA levels of the serotonergic and Creb genes are reduced in the winners in
comparison with male mice without consecutive positive fighting experience of
aggression. After the fighting deprivation the Tph2, Sert, Bdnf and Creb genes
recover their expression while mRNA
levels of the Maoa and Htr1a genes proceed at a significantly higher level as compared with the
respective controls. Downregulation of serotonergic genes is indicative of the
inhibition of serotonergic activity under repeated experience of aggression.
Nevertheless recovering of Tph2 and Sert gene expression and overexpression of the Maoa and Htr1a genes after no-fight period suggest that changes in brain
serotonergic activity are not main cause of the behavioral pathology developing
in male mice in this experimental context.