Carrageenan-Induced Non-Painful Inflammation Reduces Voluntary Sucrose Consumption in a Two-Bottle Choice Paradigm: A New Model of Inflammation Induced Anhedonia

Anhedonia, the presence of diminished pleasure or decreased motivation for rewards is considered one of the core symptoms of depression. Studies have shown that anhedonia and reduced reward learning predict a poor prognosis with a higher prevalence of treatment failure among patients. Several mechanisms have been implicated in the onset and progression of depression; furthermore, an important amount of evidence supports not only the importance of the reward circuitry in the development of depressive anhedonia but also, that it is closely related with the presence of inflammation. In the current paper we show that 500 ul carrageenan administration in the right hind paw after deafferentation surgery leads to anhedonia, which is evident by a decrease in saccharine consumption in a two-bottle choice test; these findings suggest that carrageenan mediated inflammation is a reliable model of anhedonia that could lead to a better understanding of the immune-neural axis in motivation.