Corticotropic cell

Corticotropes (or corticotrophs) are basophilic cells in the anterior pituitary that produce pro-opiomelanocortin (POMC) which undergoes cleavage to adrenocorticotropin (ACTH), β-lipotropin (β-LPH), and melanocyte-stimulating hormone (MSH). These cells are stimulated by corticotropin releasing hormone (CRH) and make up 15–20% of the cells in the anterior pituitary. The release of ACTH from the corticotropic cells is controlled by CRH, which is formed in the cell bodies of parvocellular neurosecretory cells within the paraventricular nucleus of the hypothalamus and passes to the corticotropes in the anterior pituitary via the hypophyseal portal system. Adrenocorticotropin hormone stimulates the adrenal cortex to release glucocorticoids and plays an important role in the stress response. The primary function of the corticotropic cells is to produce the prohormone POMC in response to the release of CRH from the hypothalamus. POMC is cleaved into several peptide hormones via enzyme activity. In addition to synthesis in the corticotropes, POMC is also synthesized in melanotroph cells, the arcuate nucleus of the hypothalamus, and melanocytes. POMC undergoes differential cleavage into various peptide hormones depending on the cell it is synthesized in; it also varies based on species. POMC in the corticotropes of humans is proteolytically cleaved by proprotein convertases into ACTH and β-lipotropin. In rats, however, the ACTH is further cleaved into α-MSH and CLIP in the corticotrope. These peptide hormones are stored within vesicles in the corticotropic cells and are released in response to CRH stimulation from the hypothalamus. These vesicles then leave the anterior pituitary and travel throughout the body via the bloodstream to reach their target tissues. Corticotropic cells serve an important role within the feedback loop of the hypothalamic–pituitary–adrenal (HPA) axis and the stress response. Corticotropes produce and release ACTH, a 39 amino acid peptide hormone, in response to corticotropic releasing hormone (CRH) release from the hypothalamus.