Laboratory of Fish Biology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya, Aichi, 464-8601, Japan.
Laboratory of Organic Chemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya, Aichi, 464-8601, Japan.
Sci Rep. 2022 Sep 5;12(1):15087. doi: 10.1038/s41598-022-19355-6.
Toxic puffers contain the potent neurotoxin, tetrodotoxin (TTX). Although TTX is considered to serve as a defense substance, previous behavioral studies have demonstrated that TTX acts as an attractive pheromone for some toxic puffers. To elucidate the physiological mechanism of putative pheromonal action of TTX, we examined whether grass puffers Takifugu alboplumbeus can detect TTX. Electroolfactogram (EOG) results suggest that the olfactory epithelium (OE) of grass puffers responded to a type of TTX analog (5,6,11-trideoxyTTX), although it did not respond to TTX. We also examined the attractive action of 5,6,11-trideoxyTTX on grass puffers by recording their swimming behavior under dark conditions. Grass puffers preferred to stay on the side of the aquarium where 5,6,11-trideoxyTTX was administered, and their swimming speed decreased. Additionally, odorant-induced labeling of olfactory sensory neurons by immunohistochemistry against neural activity marker (phosphorylated extracellular signal regulated kinase; pERK) revealed that labeled olfactory sensory neurons were localized in the region surrounding "islets" where there was considered as nonsensory epithelium. 5,6,11-trideoxyTTX has been known to accumulate in grass puffers, but its toxicity is much lower (almost nontoxic) than TTX. Our results suggest that toxic puffers may positively use this TTX analog, which has been present in their body with TTX but whose function was unknown, as an odorant for chemical communication or effective TTX accumulation.
含有强烈神经毒素——河豚毒素（TTX）的毒性河豚。虽然 TTX 被认为是一种防御物质，但之前的行为研究表明，TTX 对某些毒性河豚具有吸引力。为了阐明 TTX 潜在的信息素作用的生理机制，我们检查了草河豚 Takifugu alboplumbeus 是否能够检测到 TTX。电生理学（EOG）结果表明，草河豚的嗅觉上皮（OE）对一种 TTX 类似物（5,6,11-去氧TTX）有反应，尽管它对 TTX 没有反应。我们还通过记录草河豚在黑暗条件下的游泳行为，检查了 5,6,11-去氧 TTX 对草河豚的吸引力。草河豚更喜欢停留在施用药剂的水族箱一侧，且其游泳速度减慢。此外，通过针对神经活性标志物（磷酸化细胞外信号调节激酶；pERK）的免疫组织化学方法对气味感应神经元进行的标记显示，标记的嗅觉感觉神经元位于被认为是非感觉上皮的“胰岛”周围区域。已知 5,6,11-去氧 TTX 会在草河豚中积累，但它的毒性比 TTX 低得多（几乎无毒）。我们的结果表明，毒性河豚可能会积极利用这种 TTX 类似物，尽管它与 TTX 一起存在于其体内，但作用未知，但将其作为化学通讯或有效 TTX 积累的气味物质。
