A motor vehicle accident caused complete pituitary stalk transection. Secretion of all pituitary hormones is lost except for one, whose blood level actually increases. Which one of the following pituitary hormones is distinctive in that its primary control is by inhibition rather than stimulation by the hypothalamus?

Question

Quizplus · Accepted Answer

Prolactin is primarily controlled by inhibition from the hypothalamus via dopamine. When the pituitary stalk is transected, the inhibitory control is lost, leading to an increase in prolactin levels. The primary control over prolactin secretion is inhibition by hypothalamic dopamine; all other anterior pituitary hormones are primarily controlled by hypothalamic hormone stimulation. Hence, with stalk transection, loss of connection of the hypothalamus to the pituitary is associated with decreased secretion of all pituitary hormones except prolactin, whose secretion increases in the absence of dopamine.

A Motor Vehicle Accident Caused Complete Pituitary Stalk Transection