Objective To establish a rat model of granulomatous mastitis through the combination of gastrin-induced

elevation of serum lactogen and rat milk injection， and to analyze and evaluate the value of each modeling factor and index on

the model， and to explore an animal model that better fits the characteristics of the disease. Methods Sixteen adult female

Wistar rats were divided into two groups：6 rats in the normal control group and 10 rats in the model group. The normal control

group was not given any special treatment. Rats in the model group were injected subcutaneously with gastrin for 2 weeks， and

the rats were injected locally with a suspension （milk plus adjuvant） on the 1st，7th and 14th days respectively. The changes

in body weight and mammary mass size were measured once a week. Serum prolactin levels were detected by ELISA before， at

the 2nd and 4th week of modeling. After the rats were executed， the histopathological changes of mammary glands were

observed by HE staining. The serum levels of IL-1β and IL-6 were measured by high-throughput liquid-phase protein

microarray assay before and after modeling. Results After modeling， the skin and breast lumps of the model rats showed

similar clinical manifestations as those of patients with granulomatous mastitis. In terms of serum prolactin level， the PRL

level of the model group was higher than that of the normal control group at week 2（P<0.001）； The PRL level of the model group was still higher than that of the normal control group at week 4（P<0.01）. In terms of pathomorphology， some of the masses were visible as acne-like material to the naked eye， and microscopically the lesion areas were seen as multifocal scattered distribution of epithelioid cells constituting granulomatous nodules with a variety of inflammatory cell infiltrates，

mainly lymphocytes， and foamy histiocytes， plasma cells， multinucleated giant cells and macrophages. The levels of serum

interleukin 1β（IL-1β） and interleukin 6（IL-6） after modeling were higher than before modeling （P<0.01）. Conclusion  Gastrin-induced elevation of serum lactogen combined with rat milk injection can successfully establish granulomatous mastitis model after 4 weeks of modeling.

Granulomatous mastitis, Prolactin, Secretion, Wistar rats