Abstract
Whey protein is widely used as a nutritional supplement because of its high biological value, rapid digestibility, and rich content of essential and branched-chain amino acids. However, its hepatic effects may vary according to dose and duration of administration. This study aimed to evaluate the histological and histochemical alterations in the liver of adult male rats following six weeks of whey protein feeding. Fifteen adult male albino rats were randomly divided into three equal groups (n = 5 per group): a control group receiving distilled water, a low-dose whey protein group receiving 5 g/kg body weight, and a high-dose whey protein group receiving 10 g/kg body weight. Liver specimens were processed using the routine paraffin technique. Hematoxylin and Eosin staining was used to assess general hepatic architecture, hepatocyte arrangement, steatosis, inflammatory infiltration, and cellular alterations, while Masson’s Trichrome staining was applied to evaluate collagen deposition and fibrotic remodeling. The control group showed well-preserved hepatic lobular architecture, regularly arranged hepatocyte cords radiating from the central vein, and no evidence of steatosis, inflammation, necrosis, or fibrotic change. In the 5 g/kg whey protein group, liver sections showed mild to moderate macrovesicular steatosis with focal inflammatory cell infiltration, while the general hepatic architecture remained relatively preserved. Masson’s Trichrome staining revealed moderate collagen deposition, mainly in the perisinusoidal and portal/periportal regions. In contrast, the 10 g/kg whey protein group exhibited marked macrovesicular steatosis, large cytoplasmic vacuolation, peripheral displacement or fading of hepatocyte nuclei, extensive inflammatory infiltration, disruption of hepatocyte cords, and more advanced collagen deposition with bridging fibrotic changes. These findings indicate that six weeks of whey protein feeding induced dose-dependent histological and histochemical liver alterations in male rats. The lower dose produced moderate steatotic, inflammatory, and fibrotic changes, whereas the higher dose caused more severe hepatic tissue injury, architectural disruption, and advanced fibrotic remodeling. The results suggest that excessive whey protein intake may impose a progressive hepatic tissue burden under the conditions of this experimental model.