http://precedings.nature.com/users/6e237c9878ce4137bc55fca8568f59f5/ Documents posted by Natalia Bondar Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://precedings.nature.com/documents/2682/version/1 One of the core symptoms of major depression in human is anhedonia. For that reason, one of the main requirements towards experimental depression models is that they be able to demonstrate anhedonia in animals, that have been exposed to stressful events, and other behavioral changes attributable to a depression-like state. However, the results presented in the literature are contradictory: sweet solution intake, which is considered as a parameter of hedonic/anhedonic behavior in animals, responds quite differently to stressful situations in that it is either unaffected or increased or decreased. Different experimental designs used for the study of anhedonia in male mice exposed to chronic social defeat stress were tried to understand the reasons for so contradictory responses. Anhedonia appears as an abrupt reduction in sweet solution consumption in stressed animals and by failure to attain recovery after deprivation. However, it was also demonstrated that sucrose solution intake and preference strongly depend on the experimental context; that the possible critical factor may be prior acquaintance with the hedonic stimulus – or the lack whereof. Analysis of literature data and ours allowed us to conclude that the lack of a significant decrease in sweet solution intake in stressed animals is no evidence of lack of depression. This decrease is evidence of anhedonia only provided other symptoms of depression are present. Hedonic consumable intake can be decreased over various motivations, conditions or diseases, in particular, a high level of anxiety or pathological aggression. http://precedings.nature.com/documents/2682/version/1 Fri, 19 Dec 2008 11:32:06 UTC Anhedonia in the shadow of chronic social defeat stress, or When the experimental context matters hdl:10101/npre.2008.2682.1 2008-12-19 Natalia N. Kudryavtseva Nature Precedings 2008-12-19T11:32:06Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/2042/version/1 Th, Dat1, Snca and Bdnf were the genes whose mRNA levels in the ventral tegmental area of the midbrain were measured in male mice that were victorious in 20 daily agonistic interactions and in a group of such victorious mice that had later not been allowed to fight for 14 days. This experiment demonstrated increased Th, Dat1 and Snca but not Bdnf mRNA levels in the former group as compared to the controls. In the latter group, the expression of the Th and Dat1 genes was still enhanced, while the level of Snca mRNA did not differ from that in the controls. These findings suggest that positive fighting experience enhances the expression of the genes concerned with dopaminergic systems and this enhanced expression is preserved for a long time afterwards. Significant positive correlations were found between the level of aggression and Th and Snca mRNA levels in the winners. http://precedings.nature.com/documents/2042/version/1 Thu, 10 Jul 2008 09:27:53 UTC Molecular implications of prolonged aggression experience: Th, Dat1, Snca and Bdnf gene expression in the ventral tegmental area of the victorious male mice hdl:10101/npre.2008.2042.1 2008-07-10 Natalia N. Kudryavtseva Nature Precedings 2008-07-10T09:27:53Z Manuscript Molecular Cell Biology Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/2043/version/1 Th, Dat1, Snca and Bdnf were the genes whose mRNA levels in the ventral tegmental area of the midbrain were measured in male mice that were victorious in 20 daily agonistic interactions and in a group of such victorious mice that had later not been allowed to fight for 14 days. This experiment demonstrated increased Th, Dat1 and Snca but not Bdnf mRNA levels in the former group as compared to the controls. In the latter group, the expression of the Th and Dat1 genes was still enhanced, while the level of Snca mRNA did not differ from that in the controls. These findings suggest that positive fighting experience enhances the expression of the genes concerned with dopaminergic systems and this enhanced expression is preserved for a long time afterwards. Significant positive correlations were found between the level of aggression and Th and Snca mRNA levels in the winners. http://precedings.nature.com/documents/2043/version/1 Mon, 07 Jul 2008 12:31:48 UTC Molecular implications of prolonged aggression experience: Th, Dat1, Snca and Bdnf gene expression in the ventral tegmental area of the victorious male mice hdl:10101/npre.2008.2043.1 2008-07-07 N. N. Kudryavtseva Nature Precedings 2008-07-07T12:31:48Z Manuscript Molecular Cell Biology Neuroscience http://creativecommons.org/licenses/by/3.0/