Hypothalamic-releasing hormones

The hypothalamic releasing hormones are peptides. They reach their target cells in the AH lobe by way of a portal vascular route consisting of two serially connected capillary beds. The first of these lies in the hypophyseal stalk, the second corresponds to the capillary bed of the AH lobe. Here, the hypothalamic hormones diffuse from the blood to their target cells, whose activity they control. Hormones released from the AH cells enter the blood, in which they are distributed to peripheral organs (1),... 

Hypothalamic releasing hormones are mostly administered (parenterally) for diagnostic reasons to test AH func-tioa... 

Anterior part produces its own hormones in response to hypothalamic releasing hormones, e.g., adrenocorticotropic hormone ACTH, luteinizing hormone LH, follicle-stimulating hormone FSH, prolactin, growth hormone, thyroid-stimulating hormone TSH Thyroid Regulation of metabolism, development, and maturation... 

In opposition to what we normally see with all of the other pituitary hormones, the hypothalamus predominantly suppresses prolactin release from the pituitary gland. In other words, there is usually a hypothalamic "Stop that" order set against the lactotroph, and prolactin is released only when the order is released. A note of interest is that If the pituitary stalk is severed, prolactin release increases, while secretion of all the other pituitary hormones decreases dramatically due to loss of hypothalamic releasing hormones. But this is an unlikely scenario for most athletes and should obviously be avoided nonetheless. 

Reviews of TRH and other hypothalamic releasing hormones Schally et al, Recent Progr. /form. Res. 24, 497... 

Meij, B. P, J. A. Mol, and A. Rijnberk. 1996. Thyroid stimulating hormone responses after single administration of thyrotrophin-releasing hormone and combined administration of four hypothalamic releasing hormones in beagle dogs. Domestic Animal Endocrinology 13 465-468. 

PITUITARY HORMONES AND THEIR HYPOTHALAMIC RELEASING HORMONES... 

CHAPTER 55 Pituitary Hormones and Their Hypothalamic Releasing Hormones 969... 

It is beyond the scope of this review to discuss, except in brief outline, the hypothalamic substance, thyrotropin-releasing hormone (TRH), and its application in clinical chemistry, although many publications on TRH have appeared over the last five years or so. However, only a limited number of clinical applications of TRH are related primarily to the thyroid gland. Some reviews which include information on TRH have appeared recently (H7, H14, S8). A review on hypothalamic releasing hormones appears in this volume (H6A). Reference to the physiological role of TRH has been made in Section 2.4. 

Brownstein, M., 1982, Hypothalamic Releasing Hormones, Non-endocrine Aspects, in Handbook of Psychopharmacology, (L. L. Iversen, S. D. Iversen, and S. H. Snyder, eds.), Vol. 17, in press. Plenum Press, New York. 

---