Effects of 4-methylbenzylidene camphor (4-MBC) on neuronal and muscular development in zebrafish (Danio rerio) embryos

Abstract

The effects of UV light on human is of increasing public concern. The majority of negative effects caused by over-exposure of sunlight include sunburn and light-induced cell injury. UV filter is used extensively in many sunscreen products to protect human skin from the negative effects of UV radiation. Methylbenzylidene camphor (4-MBC) is one of the active ingredients in sunscreens products. 4-MBC is a UV filter that dissipates the absorbed radiation energy as heat by photo-induced geometrical isomerization. Its adverse effects has been studied and it was found that 4-MBC has potential to act as endocrine disruptor. It has been shown to exert estrogenic effects in both in vitro and in vivo studies. However, little information is known about the neurotoxicity in early vertebrate development. In this study, the effects of 4-MBC exposure on zebrafish embryonic development were examined. Embryos exposed to 4-MBC at nominal concentration of 15uM displayed abnormal axial curvature and exhibited ineffective tail flip and muscle contractions along the body axis in response to tactile stimulation. 4-MBC exposed embryos showed abnormal notochord pattern and loss of muscle pioneer cells, which may lead to the disruption of motor axon innervations and slow muscle development during somitogenesis. Taking these results together, it can be proposed that 4-MBC causes locomotion defects by impairing muscular and neuronal development.