Dehydration is a powerful stimulus causing disequilibrium in homeostasis of water and
electrolytes resulting from depletion in total body water. Most studies have focused on domestic and laboratory animals; however, the study of desert animals allows improved understanding about water balance and resistance to
dehydration and associated behavioral changes, including those related to
mood disorders. Meriones shawi (Shaw's Jird) is a desert rodent characterized by its resistance to long periods of thirst that can extend for several months. In the present study, M. shawi were subjected to water deprivation for 1 and 3 months. We used
5-HT immunohistochemistry to evaluate the effects of prolonged
dehydration on the serotoninergic system in both dorsal and median raphe nuclei (DRN, MRN), which are the main sources of
5-HT input to several brain areas. In addition, a dark/light box was used to evaluate the
anxiolytic-like or anxiogenic-like effects of
dehydration on M. shawi. The results showed a reduction in the
5-HT immunolabelling in both DRN and MRN following 1 and 3 months of
dehydration. This diminution of
serotonin immunoreactivity was accompanied by noticeable changes in anxiety behavior of Meriones, with animals spending more time in the light box, suggesting anxiogenic-like effects caused by
dehydration. Overall, the results indicate that
dehydration is able to reduce serotoninergic neurotransmission, which might be involved in generating anxiety behavior in this desert animal.