This document discusses androgens, which are steroid hormones that include testosterone and dihydrotestosterone. Androgens are primarily produced in the testes of males by Leydig cells, which synthesize testosterone from cholesterol through various enzymatic pathways. Testosterone is transported bound to albumin or sex hormone binding globulin and is metabolized in the liver before being excreted in urine. Androgens play important physiological roles in male development, libido, and pubertal growth.

1. NATURE AND
SYNTHESIS OF
ANDROGEN
Prepared by: Anish Dhakal (Aryan)
MBBS Student
Patan Academy of Health Sciences

2. • Androgen is a steroid hormone.
• Types :
• 1. Testosterone
• 2. Dihydrotestosterone
• 3. Androstenedione
• 5-12 mg of testosterone produced daily by testes
• converted to more active form dihydrotestosterone in extra glandular tissues.
• 19 carbon compounds

3. Testosterone A prohormone!
Dihydrotestosterone (DHT) more potent than testosterone.

4. ANDROGENS
 Sites of synthesis in males -- primarily testes-leydig cells; also in adrenals (zona
reticularis and fasciculata)
 Androgens in Females
 Sites of synthesis-ovaries; tiny amount by theca cells of ovarian follicles,
adrenals, placenta
 Physiological significance
• Apparently not necessary for normal menstrual cycling, but may be involved in
pubertal growth spurt, libido.
• Precursor of hormone is cholesterol.

5. TESTOSTERONE: LEYDIG CELLS
• Cholesterol can either be synthesized de novo in the Leydig cell
• can also be LDL derived
• Migrate to inner mitochondria by stAR (steroidogenic Acute Regulatory) protein
• first converted to Pregnenolone by Cyt P450 side chain cleavage
enzyme (P450SCC) which then forms androstenedione by two
pathways:
1. Through progesterone (Progesterone (or ∆4) pathway)
2. Through 17-hydroxypregnenolone. (Dehydroepiandrosterone or
∆5 pathway)

7. TESTESTERONE TRANSPORT
• largely bound to albumin and to a specific transport protein, Testosterone
estrogen binding protein (TEBG) or sex hormone-binding globulin (SHBG)
• Currently, protein bound testosterone is also regarded as biologically active
• Liver mainly metabolizes androgens to 17-ketosteroids,which are excreted in urine