Melatonin Modulates Behavioral and Physiological Responses in a Concentration-dependent Manner in a...

Area of Science:

• Neuroscience
• Developmental Biology
• Toxicology

Background:

• Melatonin's antioxidant properties are known, but its safety and concentration-dependent effects require further study, especially in aquatic models.
• Understanding melatonin's impact is crucial for its use in experimental systems, including seizure models.

Purpose of the Study:

• To investigate the effects of melatonin on behavioral and physiological responses in a pilocarpine-induced seizure-like model in zebrafish larvae.
• To assess melatonin's safety profile and concentration-dependent effects in aquatic experimental systems.

Main Methods:

• Zebrafish larvae were exposed to various melatonin concentrations (0.14-18 µg/mL) in a pilocarpine-induced seizure model.
• Embryo-larval toxicity, behavioral responses (hyperlocomotion, seizure onset), and biochemical markers (ROS) were assessed up to 144 hours post-fertilization.

Main Results:

• Melatonin did not affect mortality or hatching rates across tested concentrations.
• Higher melatonin concentrations (9.0 and 18 µg/mL) altered spontaneous contractions and increased heart rate.
• Lower melatonin concentrations (2.25 and 4.50 µg/mL) reduced pilocarpine-induced hyperlocomotion, increased seizure latency, and lowered reactive oxygen species (ROS) levels.

Conclusions:

• Melatonin exhibits a concentration-dependent response profile in zebrafish larvae, influencing both physiological and behavioral endpoints.
• The study highlights the importance of dose selection for melatonin in experimental seizure models.
• Findings contribute to characterizing melatonin's effects in early developmental stages within aquatic systems.