Steroid Hormones Cholesterol Starting material Steroid Sex Hormones

Steroid Hormones Cholesterol Starting material

Steroid Sex Hormones • Androgens: male sex hormones • synthesized in the testes • responsible for the development of male secondary sex characteristics

Steroid Hormones • Among the synthetic anabolic steroids are: Prohormones, see p. 515 Chemical Connections 20 G Why are these hormones of interest? Do steroids really work? i. e. improve muscle mass and performance? . . .

A resounding Yes. . .

Steroid Sex Hormones • Estrogens: female sex hormones • synthesized in the ovaries from progesterone testosterone. . . (aromatization) estradiol • responsible for the development of female secondary sex characteristics and control of the menstrual cycle

Steroid Sex Hormones A woman's monthly cycle w/o the pill (Blue and Red solid lines) A woman's monthly cycle on the pill (Blue and Red dashed lines) • Progesterone-like analogs are used in oral contraceptives: they Make the body think it is Pregnant at all times. . . preventing folicle stimulation and ovulation. . .

• Steady stream of Progesterone required for implantation and development of oocyte Other pills block Progesterone all together. . . e. g. RU- 486 Progesterone Prevents egg from staying implanted. . Gets released. . .

Steroid Hormones • Adrenocorticoid hormones • • synthesized in the adrenal cortex. regulate metabolism of carbohydrates. decrease inflammation. involved in the reaction to stress.

Bile Salts • Bile salts, salts the oxidation products of cholesterol. • synthesized in the liver, stored in the gallbladder, and secreted into the intestine where they emulsify dietary fats and aid in their absorption and digestion

Other Classes Lipids: - Prostaglandins - Thromboxanes - Leukotrienes • Prostaglandins: a family of compounds that have the 20 -carbon skeleton of prostanoic acid.

Prostaglandins • Not stored in tissues - synthesized from membrane-bound 20 -carbon polyunsaturated fatty acids in response to specific physiological triggers. • One such polyunsaturated fatty acid is arachidonic acid.

Prostaglandins

COX Enzymes • The COX (cyclooxygenase) enzyme occurs in two forms: • 1. COX-1 catalyzes the normal physiological production of prostaglandins. • 2. COX-2 is responsible for the production of prostaglandins in inflammation. • Tissue is injured or damaged, special inflammatory cells invade the injured tissue and interact with resident cells, e. g. smooth muscle cells or skin. • This interaction activates COX-2 and prostaglandins are synthesized. Aspirin helps relieve this anti-inflammatory response By inhibiting the production of prostaglandins. . .

Thromboxanes • Thromboxanes are also derived from arachidonic acid. • Thromboxane A 2 induces platelet aggregation and vasoconstriction. • Aspirin and other NSAIDs inhibit the synthesis of thromboxanes by inhibiting the COX enzyme.

Challenge Questions How Does Aspirin prevent strokes caused by blood clots in the brain? NOTE: Doctors recommend 81 mg/ day for people at risk for Heart Attack or stroke. . .

Leukotrienes • Leukotrienes are also synthesized from arachidonic acid. • They occur mainly in leukocytes. • They produce muscle contractions, especially in the lungs and thereby can cause asthma-like attacks. • In this regard, they are 100 times more potent than histamine. • Several recently-developed anti-asthma drugs inhibit the synthesis of leukotrienes.