Effects of Gabapentin, Valsartan, and Codeine on hemato-biochemical and histological biomarkers of male catfish (Clarias gariepinus)

Abstract

Pharmaceutical residues in aquatic environments are emerging contaminants of concern due to their potential sublethal and chronic impacts on aquatic organisms. This study aimed to evaluate the subacute toxicological effects of three widely used pharmaceuticals-gabapentin (GAB), valsartan (VAL), and codeine (COD)-on male African catfish (Clarias gariepinus). Fish were randomly assigned to four groups: a control group and three treatment groups exposed for 15 days to environmentally relevant concentrations of GAB (79.86 µg/L), VAL (28.22 µg/L), and COD (5.27 µg/L), respectively. Hematological indices including hematocrit (Ht), hemoglobin (Hb), erythrocyte (RBC), leukocyte (WBC), and lymphocyte counts were significantly reduced in all exposed groups relative to controls. Biochemical analysis revealed elevated levels of AST, ALT, glucose, total protein, total cholesterol, uric acid, and creatinine in the GAB group, while VAL exposure led to increased total protein and creatinine levels and decreased alkaline phosphatase (ALP) activity. Antioxidant assessments showed a significant reduction in superoxide dismutase (SOD) following VAL exposure, with total antioxidant capacity (TAC) and catalase (CAT) activities significantly reduced across all treated groups. Histopathological and histochemical examinations of the liver revealed tissue degeneration, fibrosis, and glycogen depletion, with the most severe alterations observed in the VAL group. These findings highlight the potential adverse effects of chronic pharmaceutical exposure on fish physiology and liver function, with VAL demonstrating the most pronounced impact among the tested compounds.

Keywords: Clarias gariepinus; Antioxidant enzymes; Codeine; Gabapentin; Liver histopathology; Pharmaceuticals; Valsartan.

Fig. 1

Representative liver sections of Clarias gariepinus from all experimental groups stained with hematoxylin and eosin (H&E), magnification × 400. (a) Control group: Normal hepatic architecture showing hepatocytes (H), blood sinusoids (BS), central vein (CV), and Küpffer cells (KC). (b) Gabapentin-treated group (GAB): Marked pathological changes including infiltration of inflammatory cells (IFC), necrosis (N), hydropic degeneration (HD), hemorrhage (Hr), fatty deposition (FD), dilated blood vessels (DBV), and prominent melanomacrophage centers (MMCs). (c) Valsartan-treated group (VAL): Hepatic alterations include pyknotic nuclei (PK), HD, IFC infiltration, ruptured central vein wall (RCV), hemorrhage (Hr), increased MMCs, and activated KC. (d) Codeine-treated group (COD): Observed changes include dilated central vein (DCV), HD, Hr, increased IFC infiltration, and numerous MMCs

Fig. 2

Periodic acid–Schiff (PAS)-stained liver sections of Clarias gariepinus from all experimental groups, highlighting polysaccharide (glycogen) distribution (PAS, × 400). (a) Control group: Hepatocytes show intense PAS-positive staining indicating abundant cytoplasmic glycogen deposits (black arrow). (b) Gabapentin-treated group (GAB): Marked glycogen depletion is evident; most hepatocytes exhibit weak PAS staining. A few cells contain residual glycogen (star) and fat granules (FG). (c) Valsartan-treated group (VAL): Moderate PAS reactivity with a noticeable increase in cytoplasmic polysaccharide content compared to GAB. (d) Codeine-treated group (COD): Slight increase in PAS-positive staining; only a few hepatocytes retain visible glycogen granules (black arrow)

Fig. 3

a–d Picrosirius red-stained liver sections of Clarias gariepinus from all experimental groups, highlighting collagen fiber distribution (× 400). a Control group: Normal collagen distribution confined to the capsule (arrow) and central vein (CV). b Gabapentin-treated group (GAB): Increased collagen deposition observed around the wall of the central vein (CV). c Valsartan-treated group (VAL): Enhanced collagen intensity noted in the portal area (PA), indicating early fibrotic changes. d Codeine-treated group (COD): Extensive collagen accumulation surrounding the portal area (PA) and melanomacrophage centers (MMCs), suggesting marked fibrotic response