Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5923359 | Physiology & Behavior | 2015 | 6 Pages |
Abstract
Drinking behavior is regulated by endogenous factors such as the hydration condition of animals and exogenous factors such as the taste of ingested fluids. These factors have been suggested to interact with each other via serotonergic (5-HT) signaling to regulate drinking behavior. In the present study, we examined how dehydration affects the intake of bitter water, which suppresses drinking behavior, via 5-HT signaling. Water deprivation increased water intake for 1Â h, depending on the duration of water deprivation. The intake of 1Â mM quinine, which is a bitter tastant, was lower than that of water in mice deprived of water for 24Â h but not 48Â h. We next examined the involvement of the dorsal raphe nucleus (DRN) and median raphe nucleus (MRN), which contain a large population of 5-HT neurons, in changing tolerance for quinine intake after water deprivation. The intake of quinine following water deprivation for 24Â h, but not 48Â h, increased the number of tryptophan hydroxylase-positive neurons expressing c-Fos in the DRN, but not in the MRN. Moreover, administration of paroxetine, a selective serotonin reuptake inhibitor, decreased the intake of quinine solution, but not water, in mice deprived of water for 48Â h, indicating that paroxetine treatment restored the aversion to quinine. These results suggest that unresponsiveness of 5-HT neurons in the DRN may be involved in the dehydration-induced increase in tolerance for bitter water.
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Authors
Masaki Iwai, Yoshikage Muroi, Ken-ichi Kinoshita, Toshiaki Ishii,