Toxic effects of nitrite and microplastics stress on histology, oxidative stress, and metabolic function in the gills of Pacific white shrimp, Litopenaeus vannamei

Nitrite and microplastics are environmental pollutants that threaten the health of aquatic animals and tend to affect the respiratory and metabolic functions of gills. In this study, we investigated the effects of nitrite and microplastic stress, individually and in combination, on the gills of Litopenaeus vannamei. After 14 days of exposure, both nitrite and microplastic stress caused gills deformation and vacuolization, while oxidative stress was induced by increasing the expression of catalase (CAT), superoxide dismutase (SOD), thioredoxin (Trx), heat shock protein 70 (HSP70) and heat shock protein 90 (HSP90) genes. The metabolism of carbohydrates, lipids and amino acids were altered, and 14 metabolite markers were identified. The expression of part of genes in PPAR signaling pathway was different. These results reveal that nitrite and microplastic stress adversely affect the gill physiological homeostasis of L. vannamei by causing histological damage, inducing oxidative stress and interfering with metabolic functions.