Daytime and Nighttime Disturbances Trigger Sex-Dependent Shifts in Sleep-Homeostatic Pathways, Neuromodulators, and Feeding Performance in Zebrafish (Danio rerio).

Introduction: Sleep and arousal are regulated by neurochemical networks, and disrupting these processes can affect downstream behaviors such as feeding. We evaluated daytime and nighttime mechanical disturbances on activity, sleep-homeostatic markers, regulatory pathways, and feeding in zebrafish. Methods: Adult males and females were subjected to 6-h mechanical vibrations (13:00–19:00 h or 21:00–03:00 h) over two days. Day and nighttime locomotor activity was recorded, and ratios were calculated relative to baseline. Food intake behavior was evaluated, and brains dissected for RT-qPCR analysis of purinergic sleep-homeostatic (ada, adora1, adora2), cholinergic (chat), catecholaminergic (th), and neuronal activation (cfos) markers. Results: Nighttime disturbances increased nocturnal activity in males and downregulated ada, while in females they only upregulated adora1 without altering activity. Daytime disturbances altered male activity transiently and reduced chat, whereas females showed delayed nocturnal hyperreactivity, increased ada and adora1, downregulated th and cfos, and a significantly slower food intake speed. Male feeding remained unaffected. Conclusion: Mechanical disturbances trigger sex-dependent responses in zebrafish. Males show immediate vulnerability affecting purinergic and cholinergic pathways, whereas females display a delayed impact after daytime disturbances, where shifts in sleep-homeostatic markers and regulatory pathways impair feeding performance.