We surgically prepared a hypergastrinemia model in rats and studied the effects of hypergastrinemia on chemically induced carcinogenesis in the esophagus. Operations were performed on 5-week-old male Donryu rats as follows: (1) truncal vagotomy plus pyloroplasty (group V), (2) segmental gastrectomy plus pyloroplasty (group G), (3) antrectomy (group A), and (4) no operation (group C) as a control. From the age of 6 weeks, the animals were given 0.003% N-methyl- N-amylnitrosamine (MAN) solution as drinking water for 8 weeks. After 20 weeks of MAN administration, the animals were bled and killed. The average serum gastrin levels in groups V and G were significantly higher than those groups C or A. There were significant differences between C and V in the incidence of carcinoma, and between V and A in the incidence of carcinoma including severe dysplasia. The incidence of histologically identified lesions per animal was determined, and significant differences were observed between C and both V and G in the incidence of carcinoma including severe dysplasia. Furthermore, we also detected gastrin receptors in the esophageal lesions produced by the oral administration of MAN to rats. The results of the present study suggest that endogenous hypergastrinemia has a positive influence on chemically induced carcinogenesis in the rat esophagus.

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