Gibberellic acid induced oxidative stress, mitochondrial division/fusion imbalance, and autophagy in the ovary of Carassius auratus.

Gibberellic acid (GA3), a widely used plant growth regulator, has the potential to enter the animal food chain. However, there is limited information regarding its reproductive toxicity in female fish. This study aimed to elucidate the potential mechanisms underlying GA3-induced reproductive toxicity in the ovaries of 120 female Carassius auratus (each weighing 10 ± 2 grams,) exposed to 0, 50, 100, and 150 mg/L of GA3 for 60 days. The results showed that GA3 exposure caused oxidative stress, hormonal imbalances, mitochondrial dysfunction, and autophagy in ovarian tissue. It also disrupted follicular development and lowered reproductive hormones LH and FSH. Additionally, GA3 down regulated steroidogenesis genes StAR and 3β-HSD, reduced antioxidant enzyme activity, and suppressed antioxidant gene expression (sod, gsh, gpx). It also inhibited Nrf2 signaling by reducing mRNA and protein levels of Nrf2, Nqo1, and Ho-1. GA3 disrupts mitochondrial division and fusion by altering genes like Drp1, Mff, Opa1, Mfn1, and Mfn2. It significantly upregulates autophagy-related genes (mTOR, p62, LC3-II, Atg5, Atg12) and activates the AMPK energy stress sensor, enhancing autophagy via the AMPK/ULK1/mTOR pathway. This study presents novel insights into GA3-induced oxidative stress, mitochondrial dysfunction, and autophagy, highlighting their critical roles in reproductive toxicity.