Abstract

Aims: (1) To investigate the histological changes in lingual papillae following lead toxicity in experimental rats. (2) To assess the possible protective effects of honey and black seed using light microscopy (LM) and scanning electron microscopy (SEM). Materials and Methods: Forty adult male albino rats were divided into four groups, 10 rats/group. Group I (control): 1 ml distilled water. Group II (lead): 16.5 mg lead acetate. Group III (honey + lead): 16.5 mg lead acetate + 50 mg/kg honey. Group IV (black seed + lead): 16.5 mg lead acetate + 50 mg/kg black seed aqueous suspension. All doses were given by oral intubation daily/6 weeks. After 6 weeks, rats were terminated, and tongues were decimated for LM and SEM. Results: True filiform papillae in Group II were distorted. Some appeared shorter while others had eroded tips and hyperkeratosis. Areas of epithelial erosion with complete loss of papillae and keratin were seen in some samples. Disfigured fungiform papillae with swollen taste buds were seen. In Group III, filiform and fungiform papillae appeared close to normal with minimal changes. However, in Group IV papillae were distorted with hyperkeratosis and limited areas of epithelial erosions were seen. Conclusion: The atrophy observed in Group II could be explained by lead-induced oxidative stress. Lead toxicity had a dual effect where increased free radical formation together with depletion of endogenous antioxidant enzymes resulted in inflammation and increased cell injury. Lead causes anemia and decreased salivary secretion, which may explain the epithelial erosion. Honey exerted its protective role through restoring enzymatic activity and through its antioxidant mechanism. Black seed offered lower protection than honey. Increased dose and/or duration of co-administration of black seed may improve protection.

Key words: Occupational lead toxicity, honey, black seed, filiform papillae, epithelial erosion, fungiform papillae, taste bud, SEM, antioxidant.