Toxicologic effect of short-term enrofloxacin exposure on brain of Carassius auratus var. Pengze.

To further explore short-term exposure of enrofloxacin (ENR) induced toxicity in crucian carp brain that has been reported by our previous work, as well as the possible toxicological mechanisms, this study investigated the blood-brain barrier (BBB) permeability to low dosage of ENR through comprehensively assessing expression of BBB constitutive molecules zonula occludens-1 (ZO-1) and permeability glycoprotein (P-gp), as well as ENR residue in brain of crucian carp. Toxicologic effect of ENR on brain tissue was determined through evaluating expression of brain-derived proteins S100B, neuron specific enolase (NSE) and glial fibrillary acidic protein (GFAP) in crucian carp brain tissue, as well as contents of the proteins in serum. The toxicological mechanisms were explored through analyzing transcriptome analysis data. Results showed that ENR possessed excellent permeability to crucian carp BBB, which was closely related to deranged BBB structure and declined ENR efflux that were attributed to downregulated expression of ZO-1 and P-gp by ENR exposure. Meanwhile, S100B, NSE and GFAP were upregulated in brain by ENR, and came out into blood across the damaged BBB. These data revealed that ENR induced disruption of BBB and damage of brain tissue in crucian carp. Transcriptome analysis data indicated that ENR induced toxicologic effect might be related to modification of metabolism, organismal systems, and genetic information processing, etc., and that PI3K/Akt, MAPK, HIF-1, and ubiquitin mediated proteolysis involved the mechanisms, most of the mechanisms were attributed to ENR induced oxidative stress in crucian carp brain.