An idea which helps to know about both male and female sex hormones known as androgens, estrogens and progesterones and the differences between them. And basic information regarding sexual functionality helps us to know their necessity in our body
2. CONTENTS
• Introduction
• Formation of sex harmones
• Types of sex harmones
• Male sex harmones
• Female sex harmones
• Molecular and cellular
mechanism of action
• Harmone imbalances and
causes to human body
ESTROGEN
TESTOSTERONE PROGESTERONE
MALE SEX
HARMONE
FEMALE SEX HARMONES
3. INTRODUCTION
Sex hormones play a crucial role in regulating the
development and functioning of the reproductive
system in both males and females. These
hormones are responsible for the development of
secondary sexual characteristics, gametogenesis,
and the maintenance of reproductive functions
throughout life. Understanding the molecular
mechanisms underlying the actions of sex
hormones is essential for comprehending
reproductive physiology. In this presentation, we
will delve into the intricate molecular pathways
through which sex hormones exert their e
ff
ects.
4.
5. HOW SEX HARMONES ARE FORMED
1. Genetic Regulation: The genes responsible for the synthesis of sex hormones are
located on the sex chromosomes. In males, the key genes involved are located on the
Y chromosome, while in females, they are present on the X chromosome.
2. SRY Gene (Sex-Determining Region Y): The SRY gene is a critical gene on the Y
chromosome that plays a central role in male sex determination. During early
embryonic development, the presence of the SRY gene triggers the development of
male gonads (testes) instead of female gonads (ovaries).
3. Gonadal Di
ff
erentiation: The presence of the SRY gene in the developing gonads
initiates a cascade of gene expressions and signaling pathways that lead to the
di
ff
erentiation of testes. The SRY gene activates other genes involved in testicular
development, such as SOX9 (SRY-Box Transcription Factor 9), which promotes the
development of Sertoli cells and the production of anti-Müllerian hormone (AMH).
6. 4.Steroidogenic Genes: Within the testes, specialized cells called Leydig cells and Sertoli cells
are responsible for the production of sex hormones. Several genes are involved in the
synthesis of sex hormones, including cholesterol metabolism enzymes such as cytochrome
P450 side-chain cleavage enzyme (CYP11A1) and 17α-hydroxylase/17,20-lyase (CYP17A1). These
genes are responsible for converting cholesterol into precursor molecules, such as
pregnenolone, which is subsequently converted into testosteroneTranscription Factors and
Coactivators:
5.Transcription factors are proteins that bind to speci
f
ic DNA sequences, promoting or
inhibiting the transcription of target genes. In the context of sex hormone formation, various
transcription factors, such as SF1 (Steroidogenic Factor 1), GATA4, and NR5A1 (Steroidogenic
Factor 1 Adrenal), regulate the expression of genes involved in steroidogenesis. Coactivators
and corepressors also interact with these transcription factors to
f
ine-tune gene expression
and control hormone production.
7. 6.Hormone Secretion and Feedback Regulation: Once synthesized, sex hormones are
secreted by the respective endocrine glands (e.g., testes, ovaries) into the bloodstream.
Feedback mechanisms, involving the hypothalamus and pituitary gland, regulate the
secretion of sex hormones. Hormones such as luteinizing hormone (LH) and follicle-
stimulating hormone (FSH) released by the pituitary gland stimulate the production and
release of sex hormones from the gonads. The hypothalamus senses hormone levels in
the blood and adjusts the release of gonadotropin-releasing hormone (GnRH)
accordingly, providing negative feedback control.
8. Male sex hormones, also known as androgens, play a crucial role in
the development and maintenance of male sexual characteristics and
reproductive functions. The primary androgen in males is
testosterone, which is mainly produced in the testes, with a smaller
amount being synthesized in the adrenal glands. Understanding the
molecular and cellular mechanisms of action of male sex hormones
can shed light on their diverse e
ff
ects throughout the body is
explained in fallowing steps
1. Hormone Production and Release :Testosterone synthesis is
regulated by a complex hormonal cascade. It begins with the
release of gonadotropin-releasing hormone (GnRH) from the
hypothalamus. GnRH then stimulates the anterior pituitary gland to
release two hormones: luteinizing hormone (LH) and follicle-
stimulating hormone (FSH). LH, in particular, acts on Leydig cells in
the testes, stimulating the synthesis and secretion of testosterone.
MALE SEX HARMONES INTRODUCTION
9. 2. Receptor Binding:Once released into the bloodstream, testosterone binds to androgen
receptors (ARs) present in target tissues throughout the body. The androgen receptor is a
nuclear receptor that acts as a transcription factor. It is composed of several domains,
including a ligand-binding domain, a DNA-binding domain, and a transcription activation
domain.
3. Transcriptional Regulation:When testosterone binds to the androgen receptor, it
undergoes a conformational change, allowing it to enter the nucleus. Inside the nucleus,
the activated androgen receptor binds to speci
f
ic DNA sequences known as androgen
response elements (AREs) located in the promoter regions of androgen-responsive genes.
4. Gene Expression:Upon binding to the AREs, the androgen receptor recruits co-
activators and transcriptional machinery to promote the expression of target genes.
These target genes encode proteins responsible for mediating the diverse e
ff
ects of
androgens in di
ff
erent tissues.
10. 5. Cellular Responses:The cellular responses to androgen signaling vary depending
on the target tissue. In many tissues, such as muscle, bone, and skin, androgens
promote protein synthesis, leading to anabolic e
ff
ects that contribute to muscle
growth and bone density. Androgens also play a role in maintaining secondary sexual
characteristics, such as facial and body hair growth, deepening of the voice, and
increased oil secretion in the skin.
6. Reproductive System:In the male reproductive system, androgens are essential
for the development and maintenance of the testes, seminal vesicles, prostate gland,
and other accessory reproductive structures. Androgens promote spermatogenesis,
the process of sperm production, which is necessary for male fertility.
7. Feedback Regulation:The production of androgens is tightly regulated through a
negative feedback loop. As testosterone levels rise, they can inhibit the release of
GnRH and, subsequently, the secretion of LH and FSH. This feedback mechanism
helps maintain testosterone levels within a relatively narrow range.
11. Overall, the molecular and cellular mechanisms of action of male sex hormones,
particularly testosterone, are complex and involve interactions with speci
f
ic receptors,
gene expression regulation, and diverse physiological e
ff
ects in various tissues
throughout the body. These hormones are vital for male reproductive health, sexual
development, and maintenance of secondary sexual characteristics.
12. Female sex hormones, primarily estrogen and progesterone, play crucial roles in the
development and regulation of female reproductive functions and secondary sexual
characteristics. These hormones are produced in the ovaries, although small amounts
are also synthesized in the adrenal glands and other tissues. Let's explore the molecular
and cellular mechanisms of action of female sex hormones:
1. **Hormone Production and Release:**
- Estrogen and progesterone synthesis is controlled by a complex interplay of
hormones in the female reproductive system. The hypothalamus releases gonadotropin-
releasing hormone (GnRH), which stimulates the pituitary gland to release follicle-
stimulating hormone (FSH) and luteinizing hormone (LH).
- FSH and LH act on the ovaries, promoting the development and release of an egg
(ovulation) and the formation of the corpus luteum, which is responsible for producing
progesterone.
FEMALE SEX HARMONES INTRODUCTION
13. 2. **Receptor Binding:**
- Estrogen and progesterone bind to speci
f
ic nuclear receptors known as estrogen
receptors (ERs) and progesterone receptors (PRs), respectively.
- ERs and PRs are transcription factors that regulate gene expression upon
hormone binding.
3. **Transcriptional Regulation:**
- Once bound to their respective receptors, estrogen and progesterone receptors
undergo conformational changes, allowing them to enter the nucleus.
- Inside the nucleus, the activated receptors bind to speci
f
ic DNA sequences
called hormone response elements (HREs) located in the promoter regions of target
genes.
14. 4. **Gene Expression:**
- The binding of estrogen or progesterone receptors
to HREs results in the recruitment of co-activators and
transcriptional machinery, leading to the expression of
target genes.
- Estrogen-responsive genes are involved in various
cellular processes, such as cell proliferation,
di
ff
erentiation, and the development of secondary
sexual characteristics.
- Progesterone-responsive genes are critical for
preparing the uterus for potential pregnancy and
maintaining pregnancy if fertilization occurs.
15. 5. **Cellular Responses:**
- In target tissues, estrogen and
progesterone exert diverse e
ff
ects. Estrogen
plays a role in the development of female
secondary sexual characteristics, such as
breast development, distribution of body fat,
and regulation of the menstrual cycle.
- Progesterone prepares the uterine lining for
pregnancy, supports early pregnancy, and
helps maintain the pregnancy by inhibiting
uterine contractions.
16. 6. **Menstrual Cycle:**
- Throughout the menstrual cycle, estrogen and progesterone levels
f
luctuate, leading to
the growth and shedding of the uterine lining.
- During the follicular phase (before ovulation), estrogen levels rise, leading to the
development of the ovarian follicles and the thickening of the uterine lining.
- Around ovulation, there is a surge in LH, triggering the release of the egg and the
formation of the corpus luteum, which produces progesterone during the luteal phase.
- If pregnancy does not occur, the corpus luteum regresses, leading to a drop in
progesterone levels, which causes the uterine lining to shed (menstruation).
7. **Pregnancy:**
- During pregnancy, the placenta becomes the primary source of estrogen and
progesterone, supporting the growth and development of the fetus and maintaining the
uterine environment for a successful pregnancy.
17. In summary, the molecular and cellular mechanisms of action of female sex
hormones, estrogen, and progesterone involve binding to speci
f
ic receptors,
transcriptional regulation of target genes, and diverse e
ff
ects on various tissues
throughout the female reproductive system. These hormones are instrumental in
regulating menstrual cycles, supporting pregnancy, and contributing to the
development of female sexual characteristics.
18. What happens if harmones are imbalanced ?
•Hormonal imbalances can have a signi
f
icant impact on both physical and mental
health. In females, imbalances in estrogen and progesterone can lead to irregular
menstrual cycles, infertility, and an increased risk of breast cancer. In males,
imbalances in testosterone can cause decreased libido, erectile dysfunction, and
muscle weakness.
•Symptoms of hormonal imbalances can vary depending on the speci
f
ic hormone
a
ff
ected and the severity of the imbalance. Common symptoms include fatigue,
weight gain, mood swings, and di
ff
iculty sleeping. Hormonal imbalances can also
increase the risk of developing certain health conditions such as diabetes,
osteoporosis, and cardiovascular disease.
19. Androgens and mammalian male reproductive tract development https://doi.org/
10.1016/j.bbagrm.2014.05.020
Estrogen Hormone: Types, Synthesis, Functions and Disorders by COLLEGEDUNIA
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