Reproductive endocrinology
• Cholesterol is important for reproductive endocrinology – it is the basis for all steroids hormones
• The central endocrine centre is the hypothalamus
• The pituitary gland sits just underneath the hypothalamus, is pea-sized and is very important for
sex hormones
• Overview of areas and their hormones
o Hypothalamus
▪ Releases ‘controlling’ hormones, which cause the release of hormones from the
pituitary gland
▪ Thyrotrophin-releasing hormone (TRH)
▪ Growth hormone-releasing hormone (GHRH)
▪ Somatostatin
▪ Dopamine
▪ Vasopressin
▪ Oxytocin
▪ Gonadotrophin-releasing hormone (GnRH)
▪ Corticotrophin-releasing hormone (CRH)
o Pituitary gland
▪ More released from anterior (front) pituitary than posterior
▪ Posterior gland only releases 2 hormones
• Oxytocin
• Vasopressin (anti-diuretic hormone)
▪ Anterior pituitary
• Growth hormone
• Thyroid-stimulating hormone (TSH) (stimulated by TRH)
• Adrenocorticotrophic hormone
• Follicle-stimulating hormone (FSH) – stimulated by GnRH
• Luteinizing hormone (LH) – stimulated by GnRH
• Prolactin – for milk production and breast development
▪ Prions contaminate what is excreted by pituitary and cause prions disease (CJD –
Mad cow’s disease)
▪ FSH stimulate follicle to ovary causing ovulation
o Thyroid
▪ Used for basal metabolic rate
▪ Increase = hyperactivity
▪ Decease = fatigue
▪ Triiodothyronine (T3)
▪ Thyroxine (T2)
o Ovary
▪ Progesterone
▪ Estrogen
▪ Androstenedione
▪ Inhibin
o Testes
▪ Androgens
• Male effects
o Increase aggression
o Increase muscle mass
• Female effects
o Precursor to other hormones
o Causes acne (same in males)
, o Growth of pubic hair
▪ Estradiol
▪ Inhibin
o Placenta (during pregnancy)
▪ Progesterone
▪ Estrogen
▪ Human chorionic gonadotrophin (hCG)
• Used for pregnancy tests (urine and blood)
• Found in blood before urine
• Blood more accurate
▪ Human placental lactogen
▪ Inhibin
o Uterus
▪ Prolactin
▪ Relaxin – relaxes uterus during labour (intermittent contractions)
• Steroid hormones
o Gonadal steroids – largely synthesised and released from ovaries and testes (gonads), some
from adrenal glands
o Can be interconverted from precursors in liver
o Being cholesterol based makes them very lipid soluble – therefore can pass through
membranes (lipid bilayer) freely, without need for transport
o Estrogen important for sperm production in males
o Cortisol carries an autoimmune function
o Aldosterone importance for sodium reabsorption
o Glucocorticoids used in immune system and insulin production
o They are activated androgen and estrogen receptors
▪ Activity best predicted by receptor expression, not levels
▪ ER - estrogen receptor
▪ AR – androgen receptor
▪ PR – progesterone receptor
o Testosterone
▪ Primarily produced in Leydig cells
▪ Has anabolic effects
▪ Androgenic effects – maturation of the sex organs, puberty
▪ Metabolised to be more active - 5-dihydrotestosterone (DHT)
• Cholesterol is important for reproductive endocrinology – it is the basis for all steroids hormones
• The central endocrine centre is the hypothalamus
• The pituitary gland sits just underneath the hypothalamus, is pea-sized and is very important for
sex hormones
• Overview of areas and their hormones
o Hypothalamus
▪ Releases ‘controlling’ hormones, which cause the release of hormones from the
pituitary gland
▪ Thyrotrophin-releasing hormone (TRH)
▪ Growth hormone-releasing hormone (GHRH)
▪ Somatostatin
▪ Dopamine
▪ Vasopressin
▪ Oxytocin
▪ Gonadotrophin-releasing hormone (GnRH)
▪ Corticotrophin-releasing hormone (CRH)
o Pituitary gland
▪ More released from anterior (front) pituitary than posterior
▪ Posterior gland only releases 2 hormones
• Oxytocin
• Vasopressin (anti-diuretic hormone)
▪ Anterior pituitary
• Growth hormone
• Thyroid-stimulating hormone (TSH) (stimulated by TRH)
• Adrenocorticotrophic hormone
• Follicle-stimulating hormone (FSH) – stimulated by GnRH
• Luteinizing hormone (LH) – stimulated by GnRH
• Prolactin – for milk production and breast development
▪ Prions contaminate what is excreted by pituitary and cause prions disease (CJD –
Mad cow’s disease)
▪ FSH stimulate follicle to ovary causing ovulation
o Thyroid
▪ Used for basal metabolic rate
▪ Increase = hyperactivity
▪ Decease = fatigue
▪ Triiodothyronine (T3)
▪ Thyroxine (T2)
o Ovary
▪ Progesterone
▪ Estrogen
▪ Androstenedione
▪ Inhibin
o Testes
▪ Androgens
• Male effects
o Increase aggression
o Increase muscle mass
• Female effects
o Precursor to other hormones
o Causes acne (same in males)
, o Growth of pubic hair
▪ Estradiol
▪ Inhibin
o Placenta (during pregnancy)
▪ Progesterone
▪ Estrogen
▪ Human chorionic gonadotrophin (hCG)
• Used for pregnancy tests (urine and blood)
• Found in blood before urine
• Blood more accurate
▪ Human placental lactogen
▪ Inhibin
o Uterus
▪ Prolactin
▪ Relaxin – relaxes uterus during labour (intermittent contractions)
• Steroid hormones
o Gonadal steroids – largely synthesised and released from ovaries and testes (gonads), some
from adrenal glands
o Can be interconverted from precursors in liver
o Being cholesterol based makes them very lipid soluble – therefore can pass through
membranes (lipid bilayer) freely, without need for transport
o Estrogen important for sperm production in males
o Cortisol carries an autoimmune function
o Aldosterone importance for sodium reabsorption
o Glucocorticoids used in immune system and insulin production
o They are activated androgen and estrogen receptors
▪ Activity best predicted by receptor expression, not levels
▪ ER - estrogen receptor
▪ AR – androgen receptor
▪ PR – progesterone receptor
o Testosterone
▪ Primarily produced in Leydig cells
▪ Has anabolic effects
▪ Androgenic effects – maturation of the sex organs, puberty
▪ Metabolised to be more active - 5-dihydrotestosterone (DHT)
