Changes in the population of pituitary protein transcription factor-1 nuclei in the anterior pituitary during withdrawal and resumption of feeding in hens.

Pituitary protein transcription factor (Pit-1) is a member of a large family of protein transcription factors that include Pit-1, Oct-1, Oct-2, and Unc-86. The goal of this experiment was to determine whether the population of Pit-1-containing cells changes in the anterior pituitary of chicken by the regulation of feeding. White Leghorn hens were subjected to withdrawal and resumption of feeding. The anterior pituitaries were collected from hens at pretreatment, at 2 d after withdrawal of feeding (2DWF), and 1 d and 5 d after resumption of feeding (1DRF and 5DRF, respectively). Sections of the pituitaries were immunostained for Pit-1. They were examined under a light microscope with an image analysis computer system. The Pit-1 positive nuclei were found in the glandular cells in the cephalic and caudal lobes of the anterior pituitary in all four groups of hens. The Pit-1 cell population significantly increased in the 2DWF and 1DRF and decreased thereafter in 5DRF. These results suggests that feed withdrawal may stimulate Pit-1 expression in chicken, suggesting that Pit-1 may be involved in control of pituitary functions during the process of feed regulation.