Which of the following hormones released from the pituitary is actually synthesized in the hypothalamus?

The correct option is Anti-diuretic hormone (ADH).

To understand why, let's look at the relationship between the hypothalamus and the pituitary gland:
The pituitary gland is divided into two main parts: the anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis).

1. Anterior Pituitary Hormones: Hormones such as Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), and Adrenocorticotrophic hormone (ACTH) are synthesized, stored, and released directly by the cells of the anterior pituitary gland itself. Their release is controlled by regulatory hormones secreted by the hypothalamus into the hypophyseal portal system.

2. Posterior Pituitary Hormones: The posterior pituitary does not synthesize its own hormones. Instead, it serves as a storage and release site for hormones that are synthesized by neurosecretory cells in the hypothalamus. These hormones are:
- Anti-diuretic hormone (ADH), also known as vasopressin (synthesized mainly in the supraoptic nucleus of the hypothalamus).
- Oxytocin (synthesized mainly in the paraventricular nucleus of the hypothalamus).

These hormones travel down the axons of the hypothalamic-hypophyseal tract to the posterior pituitary, where they are stored in axon terminals and released into the bloodstream when needed.

Therefore, among the choices provided, ADH is the hormone released from the pituitary gland that is actually synthesized in the hypothalamus.