STEROID HORMONES

J E N N A B O O T H , C H R I S T A B E V E R I D G E , A B I G A I L R U T H S , A N D

P A U L A C O O K

13.10 PHYSIOLOGICAL ROLES OF STEROID HORMONES

• Cholesterol is the starting material for the synthesis of steroid hormones

• The alphatic side chain on the D ring is shortened with the removal of a six- carbon unit

• Results in progesterone

PROGESTERONE Starting compound for Sex hormonesAdrenocorticoid

ADRENOCORTICOID HORMONESProducts of adrenal glandsTwo groupsMineralocorticoids

Regulate the concentrations of ionsGlucocorticoids

Control carbohydrate metabolism

Corticoid-indicates that the site of the secretion is cortrex of the gland

MINERALOCORTICOIDS

Aldesterone is the most importantIncreased secretion Enhances the reabsorptionIncreases loss of KControls tissue swelling

GLUCORTICOIDS

• Cortisol is major glucocorticoids• Job is to increase the glucose and

glycogen in the body• Fatty acid from fat storage cells and

amino acids from body protiens to the liver

• Antiinflamitory• Used to treat inflamatory diseases

SEX HORMONESMale hormone-testosteronePromotes normal growth of the male genital organ is synthesized in the testes from cholesterol

Female sex hormones- most important is estradiol

-regulates mensral cycle -level of estradiol increase when cycle begins

CONTINUED…LH (luteinizing Hormone)is anotherTriggers ovulationThe ovulation increases progesterone level

Mifepristone blocks the action of progesterone

This is done by binding to the same receptor

Completely different approach is the morning pill

It has a progesertone-like compound called levonogestestrel

13.11 BILE SALTS

Products of cholesterol in oxidationCholesterol Trihydroxy derivativeEnd of aliphatic chain Carboxylic acidForms amide bond with amino acid (glycine or taurine)

Taurine has developed an importance in sports drinksEx) Red Bull contains sugars, caffeine and B vitamins as well as taurine

Bile salts are powerful detergentsOne end is hydrophilicBecause of negative charge

The rest is hydrophobicThey can disperse dietary lipids in the

small intestine into fine emulsionsFacilitates digestionSimilar to action of soap on dirt

Can also remove excess cholesterol in 2 ways

Breakdown cholesterol by themselvesCholesterol is thus eliminated with bile salts

Solubilize deposited cholesterol in the form of bile salt- cholesterol particles

13.12- PROSTAGLANDINS, THROMBOXANES, & LEUKOTRIENES

PROSTAGLANDINSProstaglandins: group of fatty-acid-like

substancesSeminal gland secretes 0.1 mg of prostaglandin

per daySmall amounts present throughout body of both sexesSynthesized in body from arachidonic acid by a

ring closure at carbons 8 & 12Enzyme catalyzing this reaction is cyclooxygenase (COX)

Product known as PGG2

PROSTAGLANDINS CONT’DProstaglandin E group (PGE) has a

carbonyl group at carbon 9Subscript indicates # of double bonds in hydrocarbon chain

Prostaglandin F group (PGF) has two hydroxyl groups on the ring at carbons 9 & 11

Other prostaglandins (PGAs and PGBs) are derived from PGE*diagram on page 294*

PROSTAGLANDINS CONT’DCOX enzyme has 2 forms in body: COX-1 and

COX-2COX-1: catalyzes normal physiological production of prostaglandinsLowers blood pressure, treats asthma, decongestant

COX-2: responsible for production of prostaglandins in inflammation Helps to produce new tissue in injuries such as: heart attack, rheumatic arthritis, & ulcerative colitis

*aspirin inhibits both COX enzymes*

Thromboxanes = another class of archidonic acid derivatives

Synthesis also includes a ring closureDerived from PGH2, but ring is a cyclic acetal

BLOOD CLOTS Thromboxane induces platelet

aggregationWhen blood vessel is ruptured, first line of defense is the platelets circulating in the blood. Forms an incipient clotThromboxane A2 causes other platelets to clump, increases clot

BLOOD THINNERSAspirin and similar anti-inflammatory

agents inhibit the COX enzymeAs a result, PGH2 and thromboxane synthesis is inhibited, and blood clotting is impaired Many physicians recommend 81 mg aspirin a day for people at risk of heart attack or stroke

Forbid patients to use it before planned surgery aspirin and other NSAIDs may cause excessive bleeding

PGH2

Thrombaxane A2

Variety of NSAIDs can inhibit COZ enzymes

Ibuprofin & indometacin (powerful painkillers) block aspirin’s effect

Eliminate anticlotting benefitsUse together is NOT recommendedAcetaminophen & diclophenac DON’T

interfere, can be taken together

LEUKOTRIENSAlso act to mediate hormonal

responsesDerived (like prostaglandins) from arachidonic acid by an oxidative mechanism

No ring closure

Leukotrienes occur mainly in white bloodcells

Also found in other body tissuesProduce long-lasting muscle

contractions, especially in lungsCan cause asthma-like attacksProstaglandins and leukotrines cause

inflammation and fever

To counteract the effects of leukotrienes:Inhibit their uptake by Leukotriene

receptors (LTRs) in the bodyZafirlukast and Zileuton

commercial drugs used to treat and control athsma