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Andrew Schally studied how the hypothalamus controls secretion by the pituitary gland through small peptides. His work helped establish a chemical connection between brain activity and the release of hormones, and he shared the 1977 Nobel Prize in Physiology or Medicine for discoveries concerning brain peptide hormone production. He worked at Tulane and the Veterans Affairs hospital in New Orleans for more than four decades.^[ref]

One important experimental question was whether separate hypothalamic signals were needed for the two gonadotropins, luteinizing hormone and follicle-stimulating hormone. Schally and colleagues' 1971 report described a purified hypothalamic factor that stimulated both. This connected a chemically characterized signal to two measured pituitary gland responses and helped establish the role of gonadotropin-releasing hormone.^[ref]

Portrait attributed to NASA in the Wikimedia Commons file record.

The anterior pituitary is the glandular part of the pituitary gland, containing biological cells that synthesize and release hormones. Signals from the hypothalamus reach it through the hypophyseal portal system: blood passes through one network of capillaries, carries releasing or inhibiting hormones down connecting blood vessels, and enters a second network beside the hormone-secreting biological cells. This provides a direct chemical route for control by the brain.^[ref]

Its products include growth hormone, prolactin and thyroid-stimulating hormone. For example, prolactin promotes milk production, whereas oxytocin released by the posterior pituitary promotes milk ejection. Making milk and moving it outward are distinct controlled processes. Similarly, thyroid-stimulating hormone stimulates release of thyroid hormones, which participate in negative feedback on the control pathway. The anterior pituitary therefore both produces hormones and relays upstream signals; it is not simply a storage site for hormones made in the hypothalamus.^[ref]

The diencephalon is a division of the forebrain surrounding the third ventricle, deep beneath the cerebral hemispheres. It includes the thalamus, hypothalamus and epithalamus. The anatomical name groups several interacting regions: circuits of the thalamus connect with the cerebral cortex, while the hypothalamus coordinates aspects of homeostasis and regulates signals to the pituitary gland.^[ref]

The relation to the third ventricle gives a useful way to read a section of the brain. The paired thalami lie beside the narrow midline fluid space; the surrounding neural tissue belongs to the diencephalic region, while cerebrospinal fluid occupies the cavity. Distinguishing the cavity from its walls connects the ventricular system to the organization of the surrounding brain.^[ref]

J. D. Hoff is an author of the 1983 study Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others, which examined how hormones from the ovary and pituitary gland change around ovulation. Its contribution was a time-resolved comparison: samples from five participants were taken at two-hour intervals over five days, allowing changes in estradiol, progesterone, luteinizing hormone and follicle-stimulating hormone to be aligned around the onset of the luteinizing hormone surge.^[ref]

That alignment exposed relationships which a single measurement could miss: the surge began abruptly near peak estradiol, while the rise in progesterone had already begun. The experiment supplied a temporal picture of the hypothalamic–pituitary–ovarian axis; temporal association by itself does not prove which change caused another. The cited paper identifies Hoff by initials, which are retained here.

The pituitary gland is an endocrine gland at the base of the brain, connected to the hypothalamus. Its anterior pituitary contains hormone-secreting glandular cells; its posterior pituitary contains the terminals of hypothalamic neurons. The two regions consequently communicate with the hypothalamus in different ways.^[ref]

For example, the anterior pituitary secretes prolactin, which promotes milk production, while the posterior pituitary releases oxytocin, which promotes milk ejection. One organ thus participates in distinct, coordinated stages of a physiological response.^[ref]

The posterior pituitary is the neural part of the pituitary gland. Peptide hormones made in the soma of hypothalamic neurons travel down their axons and are released from terminals into the blood. The location of release is therefore different from the location of synthesis.^[ref]

Its released hormones include oxytocin and vasopressin. The latter helps the kidneys conserve water. This is an example of a neuron producing an endocrine output: an electrical signal at its terminal can cause a chemical signal to enter the circulation.^[ref]