Snca and Bdnf gene expression in the VTA and raphe nuclei of midbrain in chronically victorious and defeated male mice

The study aimed to analyze the mRNA levels of Snca and Bdnf genes in the ventral tegmental area (VTA) and raphe nuclei of the midbrain in male mice that had each won or defeated 20 encounters in daily agonistic interactions. Groups of animals that had the same winning and losing track record followed by a no-fight period for 14 days were also studied. Snca mRNA levels were increased in the raphe nuclei in the losers and in the VTA of the winners. After fighting deprivation Snca mRNA levels were decreased to the control level in both groups. Snca mRNA levels were similar to the control level in the VTA of the losers and in the raphe nuclei of the winners. However Snca gene expression was increased in these areas after no-fight period in the winners and losers in comparison with respective mRNA levels in the undeprived animals. Significant positive correlations were found between the mRNA levels of Snca and Bdnf genes in the raphe nuclei. It was concluded, that social experience affects Snca gene expression depending on brain areas and functional activity of monoaminergic systems in chronically victorious or defeated mice

The normalized <i>Snca</i> and <i>Bdnf</i> mRNA levels in the VTA and raphe nuclei of midbrain of the controls (white columns), 20-time winners and 20-time losers (grey columns) and no-fighting winners and no-fighting losers (black columns).

<p>* <i>p</i><0.05; ** <i>p</i><0.01; *** <i>p</i><0.001; # - 0.05<<i>p</i><0.1 comparisons between respective groups.</p

Primer and probe sequences.

<p>Primer and probe sequences.</p

Significant correlations between the mRNA levels of the <i>Th</i>, <i>Dat1</i>, and <i>Snca</i> genes in the VTA of the “undeprived” and the “deprived” winners and the parameters of aggressive behavior during the 20^st confrontation.

<p>Solid lines – positive correlation; dotted line – negative correlations, P<0.05, Spearman's rank correlation coefficient.</p

Significant correlations between the mRNA levels of the <i>Th</i>, <i>Dat1</i>, <i>Snca</i> and <i>Bdnf</i> genes in the VTA of the control, the “undeprived” and the “deprived” winners and all groups in combinations.

<p>Positive correlations: * - P<0.05; ** - P<0.01; *** - P<0.001; Spearman's rank correlation coefficient.</p

Protocol of the experiment.

<p>Detailed explanations are given in the text. Behavior in “undeprived” and “deprived” winners as recorded during their respective last encounter.</p

The normalized <i>Th</i>, <i>Dat1</i>, <i>Snca</i> and <i>Bdnf</i> mRNA levels in the VTA of the controls, “undeprived” and “deprived” winners.

<p>* - P<0.05 vs the controls (Mann-Whitney test).</p

Behavioral data from winners in the “undeprived” and the “deprived” group during their respective last encounter.

<p>Behavioral data from winners in the “undeprived” and the “deprived” group during their respective last encounter.</p