Immunohistochemical detection of pituitary transcription factor‐1 in paraffin sections of bovine adenohypophysis after wet heat‐induced antigen retrieval

Abstract

Pituitary transcription factor-1 (Pit-1) is a tissue-specific transcription factor responsible for somatotroph (GH cell) development and growth hormone (GH) gene activation. To investigate the expression of Pit-1 protein in bovine adenohypophysis, antigen retrieval conditions for detection of Pit-1 were optimized in paraffin sections of bovine pituitary. We then localized Pit-1 and GH employing a double-immunohistochemical staining method and compared the distribution and proportion of adenohypophyseal cells containing Pit-1 and GH between Japanese Black (Blk) and Holstein (Hol) steers. Autoclave heating pretreatment of sections in Dako Target Retrieval Solution for 20-30 min enabled reliable detection of the distinct nuclear immunostaining of Pit-1. However, heat treatment in phosphate buffered saline or citrate buffer gave only a weak signal with increased background staining and false positive immunoreactions in the cytoplasm. Pituitary transcription factor-1 was abundantly expressed in the bovine anterior pituitary and the number of Pit-1 immunoreactive cells did not differ between the breeds. The proportion of GH cells relative to Pit-1 immunoreactive cells was smaller in Blk than Hol steers, suggesting an intrinsic breed difference in cellular composition of bovine adenohypophysis. The immunohistochemical technique described will facilitate further investigation of the role played by Pit-1 in the regulation of GH cell development and function in cattle.

Immunocytochemical Identification of Pit-1 Containing Cells in the Anterior Pituitary of Hens

“…Some glandular cells were negative for Pit-1 immunoreaction. These Pit-1 negative glandular cells may be deficient in cellular functions responsive to physiological conditions as reported by Vidal et al [11] and Matsuzaki et al [21]. Taken together, our results suggest that Pit-1 induction occurs in 6 types of pituitary glandular cells in the chicken.…”