Sub-chronic level FLX exposure and biomarker response in Labeo rohita.

Selective serotonin reuptake inhibitors (SSRIs) are among the most widely prescribed psychotropic medications globally used to treat depression, anxiety disorders, and related mental health conditions. Among these, Fluoxetine (FLX), recognized by its brand name Prozac, is frequently used. SSRIs increase serotonin levels in the brain, inhibiting its reuptake to enhance mood and emotional stability. However, their widespread production, consumption, and eventual environmental release are raising concerns among aquatic toxicologists and environmental biologists due to their potential impact on ecosystems and human health. This study investigated the long-term (35-days) antioxidant responses in Labeo rohita fingerlings exposed to varying concentrations of FLX (1, 10, and 100 μg/L). Compared to control groups, the activity of superoxide dismutase (SOD) in the brain significantly decreased (P < 0.05) in FLX-treated fish, except at the highest (100 μg/L) concentration on the 35^th day. Similarly, catalase (CAT) and glutathione S-transferase (GST) activity were significantly reduced (P < 0.05) across all treatments. Lipid peroxidation (LPO) levels were markedly elevated in FLX-treated fishes, signifying oxidative stress. Acetylcholinesterase activity in brain tissue decreased in FLX-treated groups. These findings provide critical baseline data for molecular toxicology, highlighting the potential effects of pharmaceutical pollutants on non-target aquatic organisms.