A bidirectional network for appetite control in larval zebrafish

Area of Science:

• Neuroscience
• Neuroendocrinology
• Behavioral Biology

Background:

• The medial and lateral hypothalamus are recognized for their roles in appetite suppression and enhancement, respectively.
• The dynamic interplay and functional significance of these hypothalamic regions in regulating feeding behavior remain underexplored.

Purpose of the Study:

• To investigate the interaction between hypothalamic nuclei during feeding and fasting states.
• To elucidate the functional significance of these interactions in regulating energy balance and feeding behavior.

Main Methods:

• Monitoring neural activity in the caudal hypothalamus (cH) and lateral hypothalamus (LH) of larval zebrafish during food deprivation and refeeding.
• Utilizing food sensory and consummatory cues to observe changes in hypothalamic activity.
• Employing targeted stimulation and ablation of cH neurons to confirm functional relationships.

Main Results:

• Food deprivation increased activity in serotonergic neurons of the ventromedial caudal hypothalamus (cH) and decreased activity in the lateral hypothalamus (LH).
• Exposure to food cues reversed these activity patterns, aligning with opposing internal hunger states.
• Baseline activity was restored upon refeeding and return to satiety.

Conclusions:

• The caudal hypothalamus (cH) and lateral hypothalamus (LH) exhibit antagonistic activity patterns that are crucial for regulating hunger and satiety.
• These hypothalamic nuclei coordinate energy balance through the antagonistic control of distinct behavioral outputs.
• A model is proposed where cH and LH neurons regulate different phases of hunger and satiety.