25-hydroxycholesterol impairs neuronal and muscular development in zebrafish

Area of Science:

• Neuroscience
• Developmental Biology
• Toxicology

Background:

• Oxysterols, like 25-hydroxycholesterol (25-HC), play crucial roles in brain homeostasis.
• Altered oxysterol levels are implicated in neurodegenerative and neuroinflammatory diseases.
• While 25-HC's cytotoxicity is known in cell lines, its in vivo effects on neurons are less understood.

Purpose of the Study:

• To investigate the impact of 25-HC exposure on nervous system development in zebrafish.
• To determine the dose-dependent effects and critical developmental windows for 25-HC toxicity.

Main Methods:

• Zebrafish embryos and larvae were exposed to varying concentrations of 25-HC.
• Assessed survival rates, larval motility, primary motor axon and muscle morphology.
• Quantified neuronal network integrity and HuC-positive neuronal populations in the brain.
• Analyzed cell death in the brain and spinal cord.

Main Results:

• Zebrafish survival significantly decreased at 25-HC doses above 40 μM.
• Exposure impaired larval motility, motor axon, and muscle development.
• Reduced neuronal network formation and decreased HuC-positive neurons were observed.
• Increased cell death occurred in the brain and spinal cord.
• Exposure at later developmental stages (24 and 48 hours post-fertilization) did not affect motor axons.

Conclusions:

• Elevated 25-HC levels during early development can severely impact zebrafish nervous system development.
• These findings highlight the potential consequences of oxysterol dysregulation on neuronal development and cell survival.
• The timing of exposure is critical, with early stages being most vulnerable to 25-HC's detrimental effects.