Testosterone is the main androgen hormone produced primarily in the testes and adrenal cortex. Its secretion is controlled by two hormones - FSH and LH - released by the pituitary gland in response to hypothalamic signals. FSH stimulates Sertoli cells for sperm development while LH stimulates Leydig cells to secrete testosterone. Testosterone promotes male sex characteristics and muscle building. It is metabolized in the liver but derivatives with alkyl groups at C17 are orally active. Testosterone deficiency can cause low libido, erectile dysfunction and infertility while its pharmacological uses include treatment of low testosterone conditions and for muscle building.

1. Androgens (Testosterone)
Dr. Jasmine
Associate Prof.
MMCP

2.  Male sex hormone synthesized from cholesterol in testis and
adrenal cortex.
 Also secreted in small amount by liver and ovary (females)
 Secretion is under the control of 2 releasing factors
 FSH-RF (Follicle Stimulating Hormone)
 ICSH-RF (Interstitial Cell stimulating Hormone)/LH
Both are released by anterior pituatory gland on stimulation by
the hypothalamus.
Lecture by Dr. Jasmine Chaudhary

3.  ICSH stimulates LEYDIG cells to secrete androgens. The main
active androgen is Testosterone. Other weak androgens are
Androstendione and Dehydroepiandrosterone.
 FSH stimulates Sertoli cells for spermatogenesis or sperm
development.
Both the processes occur in seminiferous tubules of testis.
 FSH and testosterone have overlapping actions on Sertoli cells
and act synergistically
◦ Testosterone is indispensable for spermatogenesis
◦ FSH is required for production of normal quantity and quality
of sperm
Lecture by Dr. Jasmine Chaudhary

4. Lecture by Dr. Jasmine Chaudhary

5. Testosterone
 Testosterone is a steroid hormone from the androgen group.
 The main activities of testosterone are
 Androgenic or male sex characteristic promoting activity
i.e. it helps in normal development, functioning and
maintenance of male sex organ and sexual characteristics.
 Anabolic or muscle building activity
i.e. development of skeletal musculature and emotional get up
of male type
Lecture by Dr. Jasmine Chaudhary

6. Secondary sexual characteristics
 Contributes to the morphological and psychological components
of masculinity
 Stimulate growth of pubic, chest, axillary, and facial hair and
muscle growth
 Adequate amounts of Dihydrotestosterone allow expression of
genes for baldness,
 Stimulates growth of the larynx and thickening of vocal chords
 Testosterone also stimulates red blood cell production
 In both men and women androgens increase sexual drive (libido )
Lecture by Dr. Jasmine Chaudhary

7. SAR
 Steroidal nucleus is essential for activity.
 Basic nucleus androstane (5-α) also possess androgenic activity.
 Ring expansion/contraction or change in configuration (5 β)
decrease or remove activity.
 Testosterone is not orally effective because metabolic changes
occurs at 17 β OH which is responsible for attachment to receptor
site. Hence 17 α alkyl group is added to prevent metabolism and
thus compound will be orally active. However increased length of
alkyl chain decrease activity.
Lecture by Dr. Jasmine Chaudhary

8.  Esterification at C-17 results in long duration of action.
 Introduction of double bond between 1 & 2 position increase
activity of 17 alpha methyl testosterone. E.g.
Methandrosterone.
 Introduction of OH at 3rd position increase activity. E.g.
Oxymesterone.
 Halogen derivative of testosterone produce compound with
decrease activity except when inserted at position 4 and 9. e.g.
4-chlorotestosterone.
 Introduction of alpha methyl at C-2 or replacement of C-2 by
Oxygen results in potent analbolic agents. E.g. Oxandrolone,
Nandrolene.
 Heterocyclic ring incorporation yield good anabolic agents.
E.g. Stanazol.
Lecture by Dr. Jasmine Chaudhary

9. Deficiency of testosterone
 Diminished libido
 Erectile dysfunction
 Infertility
 Loss of body and facial hair
 Osteoporosis
 Hypogonadism
◦ Anger, confusion, depression, and fatigue
Lecture by Dr. Jasmine Chaudhary

10. Pharmacological actions
 Given to patients suffering from improper functioning of
testis, faulty spermatogenesis and to maintain sexual
characteristics in those who have undergone surgical
castration.
 As anabolic or muscle building agents.
Lecture by Dr. Jasmine Chaudhary

11. Side Effects
 Retention of water associated with electrolytes leads to
weight gain in short term treatment but cause odema if on
long term therapy.
 17 alpha alkyl androgens cause accumulation of bile so
avoided in patients with hepatic dysfunction.
 On long term treatment, anabolic steroids suppress
endogenous production of testosterone and may lead to
impotence after their withdrawal.
Lecture by Dr. Jasmine Chaudhary

12. Nandrolene
Lecture by Dr. Jasmine Chaudhary