Cutting of the pituitary stalk decreases all of the following hormones except-
**Core Concept**
The pituitary stalk, also known as the infundibulum, connects the hypothalamus to the pituitary gland. It plays a crucial role in regulating the secretion of various hormones from the anterior and posterior pituitary glands. Cutting of the pituitary stalk disrupts the normal communication between the hypothalamus and the pituitary gland, affecting the secretion of several hormones.
**Why the Correct Answer is Right**
The pituitary stalk transmits neurohormonal signals from the hypothalamus to the pituitary gland. These signals stimulate the release of various hormones, including growth hormone, prolactin, and adrenocorticotropic hormone (ACTH). Cutting of the pituitary stalk would disrupt these signals, leading to a decrease in the secretion of these hormones. However, the posterior pituitary gland primarily releases hormones that are produced by the hypothalamus, such as antidiuretic hormone (ADH) and oxytocin. The pituitary stalk is not directly involved in the release of these hormones, as they are produced in the hypothalamus and transported to the posterior pituitary gland via axonal transport.
**Why Each Wrong Option is Incorrect**
**Option A:** Growth hormone is a hormone released from the anterior pituitary gland, which is regulated by the hypothalamus via the pituitary stalk. Therefore, cutting of the pituitary stalk would decrease growth hormone secretion.
**Option B:** Prolactin is another hormone released from the anterior pituitary gland, and its secretion is also regulated by the hypothalamus via the pituitary stalk. Cutting of the pituitary stalk would decrease prolactin secretion.
**Option D:** Adrenocorticotropic hormone (ACTH) is a hormone released from the anterior pituitary gland, which stimulates the adrenal glands to produce cortisol. The secretion of ACTH is regulated by the hypothalamus via the pituitary stalk, and cutting of the pituitary stalk would decrease ACTH secretion.
**Clinical Pearl / High-Yield Fact**
The pituitary stalk syndrome, also known as the infundibuloma, is a rare condition where a tumor or lesion compresses the pituitary stalk, leading to hypopituitarism. This condition can present with symptoms such as hypogonadism, adrenal insufficiency, and growth hormone deficiency.
**Correct Answer:** D. ADH/Oxytocin.