702
chapter 30
Endocrine Metabolism I: Introduction
TABLE 30-2
Peptide, Protein, and Glycoprotein Hormones in Humans
Released
Major
Other
Hormone
A A Residues
into Blood?1
Production Site2
Production Sites3
Thyrotropin Releasing Hormone (TRH)
3
Y
Hypoth
Methionine Enkephalin (MENK)
5
N
CNS, Hypoth
Leucine Enkephalin (LENK)
5
N
CNS, Hypoth
Angiotensin II (All)
8
Y
Blood Circulation
Antidiuretic Hormone (ADH);
9
Y
Hypoth
Arginine Vasopressin (AVP)
Oxytocin (OT)
9
Y
Hypoth
Gonadotropin Releasing Hormone (GnRH)
1 0
Y
Hypoth
Somatostatin (SS)(SRIH)
14
Y
Hypoth
Islets (P)
Endothelin-1 (ET-1 )
2 1
N
Blood vessels
Atrial Natriuretic Peptide (ANP)
28
Y
Heart
Pancreatic Glucagon
29
Y
Islets
/3-Endorphin (/3-END)
31
Y
AP, Hypoth
Calcitonin (CT)
32
Y
Thyroid C-cell
Cholecystokinin (CCK)
33
Y
Intestinal mucosa
Hypoth (S)
Adrenocorticotropic Hormone
39
Y
AP
(ACTH)(Corticotropin)
Corticotropin Releasing Hormone (CRH)
41
Y
Hypoth
Gastric Inhibitory Polypeptide (GIP)
43
Y
Intestinal mucosa
GH-Releasing Hormone (GRH)
44
Y
Hypoth
Insulin
51
Y
Islets
Relaxin
57
Y
Ovary, Placenta
Insulin-like Growth Factor I (IGF-I)
70
Y
Cartilage, liver, et al.
Parathyroid Hormone (PTH)
84
Y
Parathyroid glands
Growth Hormone (GH)(Somatotropin)
191
Y
AP
Placental Lactogen (hPL) (Chorionic
191
Y
Placenta
Somatomammotropi n)
Prolactin (PRL)
198
Y
AP
Thyroid Stimulating Hormone (TSH)(Thyrotropin)
209
Y
AP
Luteinizing Hormone (LH)
215
Y
AP
Chorionic Gonadotropin (hCG)
231
Y
Placenta
Follicle Stimulating Hormone (FSH)
236
Y
AP
1
Y = major route of dissemination to target cells is via blood transport; N = functions mainly as paracrine or autocrine hormone, although it may
enter the blood stream.
2
Hypoth= hypothalamus; CNS = central nervous system; AP = anterior pituitary (Adenohypophysis); Islets = Islets of Langerhans.
3
Restricted to those sites that are physiologically important; P = paracrine function; S = released into blood.
therefore may have evolved from ancestral extracellular
proteases.
30.3
Steroid Hormones
Four kinds of steroid hormones differ in structure and ac-
tion; they are the androgens (C
1 9
), the estrogens (Ci8),
the progestins (C
2 1
), and the corticosteroids (C
2 1
). All
are synthesized from cholesterol and are produced by
mesoderm-derived cells regulated by at least one pep-
tide hormone. Structures of the steroid hormones are
shown in Figure 30-1. The hormonal form of vitamin D
3
[l,25(OFI)2-D3] is a sterol derived from an intermediate
of cholesterol biosynthesis and is discussed in Chapter 37.
Synthesis begins with cholesterol, which in most in-
stances is acquired from circulating low-density lipopro-
tein (Chapter 20); however, all steroidogenic cells are
