Anterior pituitary cascading physiological responses. Hormone secretion from the anterior pituitary gland is regulated by hormones secreted by the hypothalamus. Neuroendocrine cells in the hypothalamus project axons to the median eminence, at the base of the brain. At this site, these cells can release substances into small blood vessels that travel directly to the anterior pituitary gland (the hypothalamo-hypophyseal portal vessels). Aside from hypothalamic control of the anterior pituitary, other systems in the body have been shown to regulate the anterior pituitary’s function. GABA can either stimulate or inhibit the secretion of luteinizing hormone (LH) and growth hormone (GH) and can stimulate
Pituitary apoplexy Pituitary apoplexy Pituitary apoplexy or pituitary tumor apoplexy is bleeding into or impaired blood supply of the pituitary gland at the base of the brain. This usually occurs in the presence of a tumor of the pituitary, although in 80% of cases this has not been diagnosed previously. The most common initial symptom is a sudden headache, often associated with a rapidly worsening visual field defect or double vision caused by compression of nerves surrounding the gland. This is followed in many cases by acute symptoms caused by lack of secretion of essential hormones, predominantly adrenal insufficiency. The diagnosis is