ABSTRACT
Medial and lateral hypothalamic loci are known to suppress and enhance appetite, respectively, but their interactions and dynamics have not yet been explored. Here we report that, in zebrafish, serotonergic neurons of the ventromedial caudal hypothalamus (cH) become increasingly active during food deprivation, whereas activity in the lateral hypothalamus (LH) is reduced. Exposure to food sensory and consummatory cues reverses the activity states of these two nuclei, reflecting an opposing internal hunger state induced by food. An intermediate activity state is restored as satiety approaches. The overall antagonistic relationship of cH and LH was confirmed by simultaneous calcium imaging, and a causal relationship was established by targeted stimulation and ablation of the cH. The collective data allows us to propose a model in which activities in anti-correlated hypothalamic nuclei direct distinct phases of hunger, and thus coordinate energy balance via mutually antagonistic control of distinct behavioral outputs.
Footnotes
Corrected typos within the text and minor figure mistakes (particularly Figure 2 - S4 and 5). We have also made some minor clarifications within figure legends. One author was added.
