Acute alkalinity stress triggers kidney histopathology, oxidative-immune dysregulation, and MAPK/TGF-β signaling pathways activation in Scatophagus argus

Saline-alkaline water aquaculture offers a promising approach to address water scarcity and increase aquatic product yields. This study investigates the effects of acute alkalinity stress on spotted scat ( Scatophagus argus ), a species known for its adaptability to various salinity conditions. We exposed S. argus to alkalinity stress for different durations (0, 12, 24, 48, 72, and 96 h) under two experimental conditions: a control group (C) with 30 ‰ salinity and 0 mmol/L alkalinity, and a treatment group (T) with 30 ‰ salinity and 30 mmol/L alkalinity. Following stress exposure, we conducted histological, biochemical, and transcriptomic analyses to assess the impact on kidney tissue. Histological results showed significant kidney damage resulting from acute alkalinity stress, characterized by enlarged nuclei, vacuolization, and necrosis of renal tubules and glomeruli. Biochemical assays revealed altered enzyme activities : levels of superoxide dismutase (SOD) and catalase (CAT) decreased, with SOD exhibiting a slight rebound at 72 h before declining again, indicating a disrupted redox homeostasis . In contrast, the activities of glutathione peroxidase (GSH-Px), malondialdehyde (MDA), acid phosphatase (ACP), and alkaline phosphatase (ALP) increased over time, reflecting oxidative stress and disruptions in metabolic and immune functions. Transcriptomic analysis identified 247 differentially expressed genes (DEGs), with 109 up-regulated and 138 down-regulated. These DEGs were significantly enriched in pathways related to immune response, cell adhesion , and protein folding , with the MAPK and TGF-β signaling pathways playing crucial roles in the stress response. These results suggest that acute alkalinity stress induces kidney damage, disrupts immune and oxidative homeostasis , and alters gene expression in S. argus , providing a deeper understanding of the molecular mechanisms underlying stress responses in saline-alkaline conditions. • Acute alkalinity stress caused histological damage in kidney of Scatophagus argus . • Acute alkalinity stress destroyed oxidative stress , immune function and metabolism of kidney in S. argus . • Acute alkalinity stress altered gene expression of pathways related to oxidative and immune in the kidney of S. argus .