Integrated analyses of hepatopancreatic response induced by high temperature and its alleviation by astaxanthin in Sinosolenaia oleivora.

High temperature (HT) is a growing threat to freshwater mollusks under climate change, yet its toxicological mechanisms and mitigation strategies remain poorly understood. This study investigated the hepatopancreatic response of an endangered bivalve Sinosolenaia oleivora to acute HT stress (35 °C for 6 h) using transcriptomic, metabolomic, and physiological biomarker analyses. Significant hepatopancreatic injury was demonstrated by TUNEL assay and histological analysis. Moreover, HT triggered severe oxidative stress, indicated by elevated antioxidant enzyme activities (SOD, CAT, GSH, T‑AOC) and malondialdehyde (MDA) levels. Multi‑omics data revealed extensive metabolic reprogramming, activation of heat shock response pathways and immune‑inflammatory pathways. Integrated analysis demonstrated oxidative stress as a central hub linking protein damage to metabolic shifts, immune activation, and cell death. Furthermore, dietary astaxanthin (0.08%) effectively alleviated HT‑induced damage by enhancing antioxidant capacity, reducing apoptosis, and preserving tissue structure. These findings provide an ecotoxicological framework for understanding acute heat vulnerability in freshwater bivalves. They also identify astaxanthin as a potential intervention to mitigate such acute heat‑induced damage.