Lasting changes induced by mild alcohol exposure during embryonic development in BDNF, NCAM and synaptophysin‐positive neurons quantified in adult zebrafish. (15th June 2018) - Mahabir, Samantha
Abstract: Fetal alcohol spectrum disorder is one of the leading causes of mental health issues worldwide. Analysis of zebrafish exposed to alcohol during embryonic development confirmed that even low concentrations of alcohol for a short period of time may have lasting behavioral consequences at the adult or old age. The mechanism of this alteration has not been studied. Here, we immersed zebrafish embryos into 1% alcohol solution (vol/vol%) at 24 hr post‐fertilization (hpf) for 2 hr and analyzed potential changes using immunohistochemistry. We measured the number of BDNF (brain‐derived neurotrophic factor) and NCAM (neuronal cell adhesion molecule)‐positive neurons and the intensity of synaptophysin staining in eight brain regions: lateral zone of the dorsal telencephalic area, medial zone of the dorsal telencephalic area, dorsal nucleus of the ventral telencephalic area, ventral nucleus of the ventral telencephalic area, parvocellular preoptic nucleus, ventral habenular nucleus, corpus cerebella and inferior reticular formation. We found embryonic alcohol exposure to significantly reduce the number of BDNF‐ and NCAM‐positive cells in all brain areas studied as compared to control. We also found alcohol to significantly reduce the intensity of synaptophysin staining in all brain areas except the cerebellum and preoptic area. These neuroanatomical changes correlated with previously demonstrated reduction of social behavior in embryonic alcohol‐exposed zebrafish, raising the possibility of a causal link. Given the evolutionary conservation across fish and mammals, we emphasize the implication of our current study for human health: even small amount of alcohol consumption may be unsafe during pregnancy. Abstract : A single, 2h long, exposure of zebrafish embryos to a low dose of ethanol at 24th hour post‐fertilization is found to lead to lasting changes in BDNF, NCAM and synaptophysin immunoreactivity. These changes are detectable in the adult zebrafish brain, and may explain the impaired social and dopaminergic neurotransmitter system responses previously reported to result from embryonic ethanol exposure in zebrafish. The zebrafish may be a useful model organism for the analysis of the mechanisms of fetal alcohol spectrum disorders.