Substance P immunoreactivity in the anterior pituitary gland of the guinea pig.

The aim of this study was to demonstrate the presence of Substance P (SP) immunoreactive cells within the anterior pituitary gland of the adult guinea pig. By utilizing the PAP technique of Sternberger, immunoreactive SP-containing cells were visualized in all animals studied. These cells were most dense in the ventral portion of the gland. When adjacent tissue sections were incubated with anti-SP serum and anti-rat TSH serum, it was observed that most, if not all, the SP immunoreactive cells examined also exhibited TSH immunoreactivity. However, not all TSH immunoreactive cells contained SP immunoreactivity. Immunoabsorption controls indicated that the immunohistochemical staining reactions were specific for both SP and TSH. The results of this study indicate that immunoreactive SP is present in the guinea pig anterior pituitary and that this peptide is localized within TSH immunoreactive cells.