Transcriptome analysis of tetrodotoxin sensing and tetrodotoxin action in the central nervous system of tiger puffer Takifugu rubripes juveniles

To reveal the sensing of tetrodotoxin (TTX) by tiger puffer Takifugu rubripes juveniles and its action in the central nervous system (CNS), we conducted transcriptome analysis using next-generation sequencing for the olfactory system and brain of non-toxic cultured juveniles administered TTX. Sixty-seven million reads from the nasal region (olfactory epithelium and skin) and the brain of each of three individuals of the control, TTX-sensing and TTX-administered juveniles were assembled into 153,958 contigs. Mapping raw reads from each sample onto the nucleotide sequences of predicted transcripts in the T. rubripes genome (FUGU version 4) and the de novo assembled contigs to investigate their frequency of expression revealed that the expression of 21 and 81 known genes significantly changed in TTX-sensing and TTX-administered juveniles in comparison with control juveniles, respectively. These genes included those related to feeding regulation and a reward system, and indicated that TTX ingestion of T. rubripes juveniles is controlled in the feeding center in the brain, that T. rubripes may sense TTX as a reward, and that accumulated TTX directly acts on the central nervous system to adjust TTX ingestion.