2. • Testosterone it is the principal male sex hormone.
• it is a steroid hormone belonging to the androgen
group.
• it is the principal male sex hormone.
• It serves several important functions beyond
reproduction.
• It is present in both males and females, but at
different levels.
• It is found in mammals, birds, reptiles, amphibians,
fish, insects, and other invertebrates.
• Introduction
3. • Testosterone is primarily produced by the gonads.
• In males, the majority of testosterone is
synthesized in the Leydig cells of the testes.
• in females, particularly in mammals, the ovaries
also release some testosterone, although the
amount is generally lower.
• Additionally, small amounts of testosterone are
also released from the adrenal glands
• Testosterone Synthesis
4. • Testosterone Biosynthesis
Hypothalamus Stimulation:
The hypothalamus releases
gonadotropin-releasing hormone
(GnRH) in a pulses average every 60 to
90 minets
Pituitary Gland Response:
GnRH stimulates the pituitary gland to
release luteinizing hormone (LH) and
follicle-stimulating hormone (FSH).
LH and FSH are released into the
bloodstream. They are carried by the
blood to the gonads
http://www.MechanismsinMedicine.com
5. www.frontiersin.org/articles/10.3389/fendo.2023.1085872/full
• Luteinizing Hormone (LH) acts on the
Leydig cells in the testes, to produce
and release testosterone with the help
Of enzymatic conversions .
• The Leydig cells, also known as
interstitial cells.
• Leydig cells found in the interstitial
tissue between the seminiferous
tubules. where sperm production
(spermatogenesis) occurs
toppr.com/3-the-seminiferous-tubules-are-lined-by-
two-types-of-cellsthat-is1-sertoli-cells-
• Luteinizing Hormone (LH)
6. The production of testosterone in the body involves a complex series of enzymatic
reactions occurring in the Leydig cells of the testes
• Testosterone Biosynthesis
Cholesterol to Pregnenolone:
Enzyme: Cholesterol is converted to
pregnenolone by the enzyme Cholesterol
Side-Chain Cleavage Enzyme (CYP11A1).
Pregnenolone to Progesterone:
Enzyme: Pregnenolone is converted to
progesterone by the enzyme
3β-Hydroxysteroid Dehydrogenase (3β-
HSD).
C27H46O
C21H32O2
7. Progesterone to
17α-Hydroxypregnenolone:
Enzyme: Progesterone is converted to
17α-hydroxypregnenolone by the enzyme
17α-Hydroxylase (CYP17A1).
17α-Hydroxypregnenolone to DHEA:
Enzyme: 17α-hydroxypregnenolone is
converted to dehydroepiandrosterone
(DHEA) by the enzyme 17,20-Lyase
(CYP17A1).
C21H30O2
C21H32O3
8. DHEA to Androstenedione:
Enzyme: DHEA is converted to
androstenedione by the enzyme 3β-
Hydroxysteroid Dehydrogenase (3β-HSD).
Androstenedione to Testosterone:
Enzyme: Androstenedione is converted to
testosterone by the enzyme 17β-
Hydroxysteroid Dehydrogenase (17β-HSD).
C19H28O2
C19H26O2
10. • Ovarian Testosterone Synthesis
• In female process begins with the development
of ovarian follicles.
• These follicles contain an oocyte (egg) and
surrounding cells contain theca cells.
• Theca cells are activated in response to
hormonal signals, including luteinizing hormone
(lh).
• Lh acts on the theca cells, leading to their
activation and the initiation of androgen
production
• The primary androgen produced by the theca
cells is androstenedione.
• Androstenedione can be further converted to
testosterone.
www.invitra.com/en/sex hormones/female-sex-
hormones/
11. • The adrenal glands produce small amounts of
androgen hormones, from innermost layer of
the adrenal cortex known as the zona
reticularis.
• The production of androgens in the adrenal
glands is primarily regulated by
Adrenocorticotropic Hormone (ACTH),
released by the pituitary gland.
• ACTH stimulates the adrenal glands to produce
and release dehydroepiandrosterone (DHEA),
which serves as a precursor to other sex
hormones, including testosterone.
• Adrenal Androgen Synthesis
https://www.shutterstock.com/sea
rch/adrenal-gland-cross-section
12. • Reproductive development
• Sperm production
• Secondary sexual characteristics development
• Muscle development
• Bone density maintenance
• Fat distribution
• Libido regulation
• Stimulation of mating behavior
• Red blood cell production
• Mood regulation
• Cardiovascular health influence
• Role of Testosterone
Testosterone plays several crucial roles in the body.
13. • Mechanism of Action
Transport in Blood: Testosterone circulates
in the bloodstream, often bound to carrier
proteins like sex hormone-binding globulin
(SHBG) and albumin, allowing it to reach
target tissues.
Cellular Uptake: Testosterone enters target
cells, either through passive or facilitated
diffusion, interacting with the cell
membrane.
Conversion to Dihydrotestosterone (DHT):
Within cells, some testosterone is
converted IN TO dihydrotestosterone (DHT),
by the enzyme 5-alpha-reductase.
14. Androgen Receptor Binding
Testosterone or DHT binds to the androgen
receptor (AR) inside the cell.
Activates the androgen receptor.
Nucleus entry:
Activated (AR) receptors,, move from
the cytoplasm to the nucleus. In the
nucleus, the receptor interacts with
DNA, activating certain genes and
influencing cellular responses.
15. • Biological Effects
The newly synthesized proteins
contribute to various biological
effects, such as the development
of secondary sexual characteristics,
muscle growth, mood regulation,
etc.
cellular responses results , cell
produces messenger RNA (mRNA). This
mRNA travels and, start synthesis of
proteins.
https://www.google.com/search?q=mRNA+Formation+and+
Protein+Synthesis%3A+TESTOSTERON
• mRNA Formation and Protein Synthesis
16. Testosterone lavel can vary based on factors such as age, sex, breed, and reproductive status.
• Humans
Males: Normal Range: 300 to 1,000 ng/dL (nanograms per deciliter).
Levels in Puberty: Gradual increase during puberty, reaching adult levels by the late teens.
typically peaking in the early morning.
Females: Normal Range: from 15 to 70 ng/dL.
• Average Testosterone Level.
• Cattle
Bulls Average Range: 400 to 1,200 ng/dL
Peak Levels: During sexual maturity and breeding season
Cows Average Range: 20 to 60 ng/dL
• Goats
Bucks Average Range: 200 to 1,000 ng/dL
Peak Levels: During the breeding season.
Does Average Range: 10 to 50 ng/dL
• Sheep
Rams Average Range: 100 to 500 ng/dL
Ewes Average Range: 10 to 50 ng/dL
17. • Equines
Stallions Average Range: 300 to 1,200 ng/dL
Peak Levels: During the breeding season, testosterone levels may increase
significantly.
Mares Average Range: 20 to 80 ng/dL
• Chickens:
Roosters Average Range: 1 to 10 ng/dL
• Dogs
Dog between 200 and 1,200 ng/dL.
Bitch 20 to 80 ng/dL.
• Cats:
Tom 300 and 1,200 ng/dL.
Queen 10 to 70 ng/dL.
• Rats and Mice
Bucks 2 to 10 ng/dL.
Does less than 1 ng/dL.
Mariya N. Erofeeva, Ekaterina V. Pavlova A.N. Severtsov Institute of Ecolo-gy and Evolution,
Russian Academy of Sciences, Moscow, Russia.
19. • Reproductive Issues. Decreased fertility.
• Sexual Dysfunction Reduced libido, erectile dysfunction, and sexual
performance issues.
• Muscle Mass and Strength Loss Decreased physical strength.
• Bone Density Reduction risk of osteoporosis.
• Changes in Secondary Sexual Characteristics Altered development of features..
• Aggression Behavior Decreased aggression.
• Metabolic Changes Increased body fat.
• Immune System Function Impaired ability to fight off infections & illnesses.
• Cognitive Function
• Alterations in Coat and Feather Quality Changes in texture and
appearance of hair, or feathers
• Low Levels Of Testosterone Can Lead To …..
