Pituitary apoplexy is attached to the hypothalamus, a part of the brain, by a stalk that also contains the blood vessels that supply the gland. It is unclear why pituitary tumors are five times more likely to bleed than other tumors in the brain. There are various proposed mechanisms by which a tumor can increase the risk of either infarction (insufficient blood supply leading to tissue dysfunction) or hemorrhage. The pituitary gland normally derives its blood supply from vessels that pass through the hypothalamus, but tumors develop a blood supply from the nearby inferior hypophyseal artery that generates a higher blood pressure,
Pituitary-specific positive transcription factor 1 for high affinity DNA binding on genes encoding growth hormone (GH; MIM 139250) and prolactin (PRL; MIM 176760). PIT1 is also important for regulation of the genes encoding prolactin and thyroid-stimulating hormone beta subunit (TSHB; MIM 188540) by thyrotropin-releasing hormone (TRH; MIM 257120) and cyclic AMP.[supplied by OMIM] Pituitary-specific positive transcription factor 1 has been shown to interact with GATA2 and PITX1. Pituitary-specific positive transcription factor 1 POU domain, class 1, transcription factor 1 (Pit1, growth hormone factor 1), also known as POU1F1, is a transcription factor for growth hormone. PIT1 is a pituitary-specific transcription factor responsible for pituitary development