Pituitary gland links the nervous and the endocrine systems in the human body

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The pituitary gland plays a crucial role in human physiology, and together with the hypothalamus this highly conserved and elegant system form a link between the nervous and endocrine system, by controlling the functions of the thyroid, adrenal glands, and the gonads, and also regulating growth, lactation, and water preservation.

This gland, also called hypophysis, consists of two separate lobes with dual embryonic origin; the anterior (adeno) pituitary gland originates from the oral cavity, and the posterior (neural) pituitary gland develops from the neural plate. The main function of the posterior pituitary gland is to secrete neuropeptides vasopressin and oxytocin into the bloodstream, produced by neurosecretory hypothalamic neurons that transport the peptides through nerve endings to the the pars nervosa - the main structure of the posterior pituitary gland.

The anterior pituitary gland can be divided into pars distalis, pars tuberalis and pars intermedia, and these regions are packed with hormone-producing epithelial cells that store hormones in secretory granules, to be released in the bloodstream. The release of hormones from the anterior pituitary is orchestrated by hypothalamic parvocellular neurons, which secretes hormone-releasing proteins that are transported to the anterior pituitary via the portal system. Once stimulated, the anterior pituitary cells release the hormones into the bloodstream to act on various tissues.

In the image, the spatial distribution and expression of three pituitary gland proteins and one hypothalamus protein is shown. The follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are important for the female and male germ cell development. FSH and LH hormones are expressed and released by gonadotrope cells in the anterior pituitary gland, and the hormone secretion is regulated by gonadotropin-releasing hormone 1 (GNRH1) expressed in hypothalamus. GNRH1 protein binds to gonadotropin-releasing hormone receptor (GNRHR) expressed on the surface of gonadotrope cells, which activates secretion of FSH and LH.

Other pituitary gland proteins annotated in the Human Protein Atlas can be accessed here.

Feria Hikmet Noraddin