A patient with a known brain tumor learns that his pituitary stalk has been affected. Secretion of which of the following hormones is increased after the sectioning of the pituitary stalk?

The secretion of prolactin is increased after the sectioning of the pituitary stalk Prolactin is unique among the pituitary hormones because the predominant central control mechanism is inhibitory, i.e., dopamine inhibits prolactin secretion. Hence, sectioning of the pituitary stalk (Ex: In head trauma or compressive skull lesion) prevents this inhibition and leads to increased secretion of prolactin. If the pituitary stalk is cut above the pituitary gland but the entire hypothalamus is left intact, the posterior pituitary hormones (ADH & Oxytoxin) show a transient decrease because they are initially synthesized in the supraoptic and paraventricular nuclei of the hypothalamus and are then transpoed down to the nerve endings to the posterior pituitary gland, requiring several days to reach the gland. Ref: Guyton and Hall 13th edition Pgno: 942