Localization of insulin-like growth factor I (IGF-I) in the chicken liver after fasting and refeeding: demonstration by using antigen retrieval immunohistochemistry.

Immunohistochemical localization of insulin-like growth factor-I (IGF-I) was investigated in the liver of fasted and refed chickens by using an antigen retrieval method. The present study is the first one showing the localization of IGF-I in the chicken liver. Immunoreactivity for IGF-I was detected on the paraffin sections of livers from the fed and refed chickens after the treatment with the antigen retrieval agent. A moderate number of cells showing IGF-I immunoreactivity were scattered in the parenchyma of the liver from fed chickens. These cells were relatively large and polygonal in shape and seemed to be hepatocytes. Reaction products were observed as a granular structure in the cytoplasm of IGF-I-immunoreactive hepatocytes. The number of immunoreactive hepatocytes was increased in the liver from refed chickens compared with fed chickens. Diffuse reaction products as well as granular ones were observed throughout the cytoplasm of IGF-I-immunoreactive hepatocytes of livers from refed chickens. There are, however, no regular patterns of the distribution of immunoreactive hepatocytes in the parenchyma of both fed and refed chickens. In the liver of the fasted chickens, clear immunoreactivity for the peptide was not observed. These data show that IGF-I is located in the chicken hepatocytes and influenced by the nutriture.