reproductive hormones

inhibin

A polypeptide/protein hormone secreted by the follicular cells of the ovary and the sustentacular = Sertoli cells of the testis which inhibits secretion of follicle stimulating hormone (FSH) from the anterior pituitary; it exerts negative feedback control on the hypothalamus and pituitary by increasing its blood levels as spermatogenesis or corpus luteum activity increase.

oxytocin (OT)

A neurohypophyseal peptide hormone which stimulates the contraction of smooth muscle of the uterus during labor and delivery and facilitates ejection of milk from the breast during nursing; its output is aided by negative feedback from the infant's suckling at the nipple.

progesterone

A steroid (cholesterol-based) hormone secreted by the corpus luteum of the ovary and by the placenta, which acts to prepare the uterus for implantation of the fertilized ovum, to maintain pregnancy, and to promote development of the mammary glands; it also provides negative feedback to the ovary to prevent further follicular development; its output is regulated by FSH and especially LH from the anterior pituitary.

prolactin (PRL)

The adenohypophyseal protein hormone which stimulates the mammary glands to produce milk; its secretion is regulated by hypothalamic PRH and aided by negative feedback from the infant's suckling at the nipple.

human chorionic gonadotropin (hCG)

The protein hormone produced only by the placenta after successful implantation of a developing embryo which signals to the hypothalamus, pituitary gland, and ovary that a pregnancy has begun; this positive feedback regulation maintains the output of estrogens and progesterone by the corpus luteum during pregnancy; this is also the hormone detected in over-the-counter urine pregnancy tests.

relaxin

A female protein hormone secreted by the corpus luteum which helps to soften the cervix and to relax the pelvic ligaments and pubic symphysis and causes appropriate smooth muscle relaxation in childbirth; in males, it is secreted by the testes, and encourages the motility of spermatozoa within semen.

GnRH = gonadotropin-releasing hormone

A protein hormone produced by the hypothalamus which stimulates (under negative feedback control by either estrogens, progesterone, and inhibin in females or androgens and inhibin in males) the anterior pituitary gland to produce and begin secreting luteinizing hormone = LH and follicle-stimulating hormone = FSH.

testosterone

A steroid hormone, the major androgen of human males, produced primarily in the interstitial cells of the testes in response to LH = ICSH and responsible for the development and maintenance of male secondary sex characteristics, sperm production, virility and libido (sexual desire); it is also produced synthetically for use in medical treatment. [Did you know testosterone levels in utero influence male behavior later in life? Click here.]

estrogens

Any of several steroid (cholesterol-based) hormones produced chiefly by the ovaries, and in minute quantities by the adrenal cortex, and responsible for promoting the development and maintenance of female secondary sex characteristics as well as regulating the uterine cycle to produce an environment suitable for the fertilization, implantation and nutrition of the developing embryo; also produced by the placenta during a pregnancy; their output is regulated primarily by FSH from the anterior pituitary.

anabolic steroids

Any of the group of synthetic analogs of testosterone, which encourage growth, especially of bone and muscle mass, and have lesser androgenic properties, which are used clinically to promote growth and repair in body tissues, to treat anemias, and for patients in negative nitrogen balance; they are also widely misused and abused by athletes, body-builders, and workers with strenuous jobs, e.g., soldiers, policemen, firemen, etc, who desire increased muscular strength; these drugs have many serious negative side-effects with long term use.

prostaglandins

Any of the group of ~20 potent local hormones which are produced in various tissues, are derived primarily from arachidonic acid (a cell membrane phospholipid) via the cyclooxygenase pathway, and mediate a wide range of physiological functions, e.g., control of blood pressure, contraction of smooth muscle, and modulation of inflammatory and immune responses; their synthesis is inhibited by aspirin and other NSAIDs. [See also Tripping Lightly Down the Prostaglandin Pathway.]

luteinizing hormone (LH)

The adenohypophyseal protein hormone which: (1) in the female: (in cooperation with FSH), regulates the ovarian cycle, stimulates ovulation and development of the corpus luteum and, thus, estrogen and progesterone production; (2) in the male: stimulates production of androgens, especially testosterone from interstitial cells; in males, it is also known as Interstitial Cell Stimulating Hormone (ICSH); LH secretion is regulated by hypothalamic GnRH.

follicle-stimulating hormone (FSH)

The adenohypophyseal protein hormone which: (1) in the female: (in cooperation with LH), regulates the ovarian cycle, stimulates maturation of the ovarian follicle and estrogen production; (2) in the male: stimulates sperm production; FSH secretion is regulated by hypothalamic GnRH.

androgens

The general name given to the class of male sex hormones, e.g., testosterone or androsterone, which are steroids produced by the interstitial cells of the testes in response to LH = ICSH, and, in much lesser amounts, by the adrenal cortex; these hormones control the development and maintenance of male secondary sex characteristics, sperm production, virility and libido (sexual desire); they also increase nitrogen and water retention and stimulate skeletal muscle growth.