Dietary astaxanthin alleviates microcystin-LR-induced hepatopancreatic digestive and absorptive dysfunction in red claw crayfish (Cherax quadricarinatus)

Astaxanthin is a functional feed additive with antioxidant and antistress properties in crustaceans. This study investigated the protective efficacy and underlying mechanisms of dietary astaxanthin against hepatopancreatic digestive and absorptive dysfunction caused by microcystin-LR (MC-LR) in red claw crayfish ( Cherax quadricarinatus ). Crayfish were fed diets containing 0, 3, 6, 9, or 12 mg/kg astaxanthin for 60 days. Growth performance was evaluated, after which crayfish from the control and 6 mg/kg groups were injected with saline or MC-LR (150 μg/kg body weight) and sampled after 24 h. MC-LR disrupted tubular architecture, reduced B cells, caused abnormal vacuolation in resorptive cells, and significantly decreased trypsin activity. Conversely, dietary astaxanthin preserved hepatopancreatic cell integrity and significantly elevated trypsin, lipase, and amylase activities during exposure. Transcriptomic analysis indicated that MC-LR suppressed genes involved in protein processing in endoplasmic reticulum (ER), proteasome, and protein digestion and absorption. Dietary astaxanthin restored the expression of key genes across these pathways, supporting protein folding, misfolded protein clearance, and nutrient transport. These findings demonstrate that dietary astaxanthin alleviates MC-LR-induced hepatopancreatic digestive and absorptive dysfunction by maintaining tissue structure, boosting digestive enzyme activities, and restoring protein homeostasis.