Histologic, Histomorphometric and Acid Secretory Changes Accompanying Gastric Ulcer Healing in Lead-Exposed Rats

• S.B Olaleye

Reported cases of environmental lead exposure and its effects on the health of humans and livestock are on the increase globally. Lead affects many biological systems leading to death if it accumulates beyond certain limits. Previous reports have shown that experimental lead exposure predisposes the stomach to gastric ulceration. However, it is not known if Lead interferes with gastric ulcer healing process. In this study, the effects of chronic lead exposure on healing of gastric ulceration with focus on histologic and gastric acid secretory changes were investigated. Sixty rats (80-100 g) were randomly divided equally into control (tap water), low and high dose (Lead acetate, 100 ppm and 5,000 ppm respectively, p.o.) groups. Twenty weeks post-treatment, ulcers were induced in the stomachs of the animals by serosal application of 60% acetic acid after anesthesia (thiopental sodium: 50 mg/Kg). In the control animals, the ulcer area was 7.9±0.1mm² by day 7 and 4.8±0.1 mm² by day 14. Lead exposure significantly increased ulcer area for low (10.0±0.4mm² and 8.0±0.4mm²) and high (14.4±0.2mm² and 10.5±0.3mm²) doses respectively. Histomorphometry revealed increased ulcer width (120.8%) in the high lead group when compared with control (100%) on day 14. Histology revealed gastric ulceration in all groups on day 7 with presence of inflammatory cells at ulcer bed. By day 14, marked reduction in the inflammatory cells and greater fibroblast proliferation were observed in control compared with the treated groups. Basal acid secretion reduced over the healing period at a lower rate in the treated groups (30.4% for low, 40.0% for high lead groups) when compared with control (60.5%). Compared with control (44.2±2.0 and 55.2±1.8/unit area on days 7 and 14), lead exposure decreased Goblet Cell Count during healing in treated groups (32.8±0.9 and 33.2±0.9 for low lead and 33.8±1.2 and 35.6±1.2 for high lead) for the same days.

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