Reproductive ageing 02/04 Flashcards
What forms the endocrine system of the reproductive system?
Hypothalamus
anterior pituitary gland.
mammary glands, testes, and ovaries.
Overview of the female reproductive system?
Hypothalamus releases gonadotrophin releasing hormone which diffuses through the portal veins to the the anterior pituitary gland. Gonadotrophs synthesise and release follicle stimulating hormone and luteinizing hormone. These enter the bloodstream, reaching their distant targets - the ovaries. The ovaries produce oestrogen, progesterone, inhibin-Band low levels ofandrogen.
What are the effects of follicule stimualting hormone on ovaries?
Ovarian follicles increase in size and secret oestrodiol. This stimulates thickening of the uterine wall, in anticipation of egg implantation.
Oestrodiol levels gradually increase throughout the follicular phase of the cycle. When they reach a threshold, this causes a surge of LH to be released, accompanied by a small surge of FSH.
What are the effects of the LH/FSH surge?
This induces ovulation from the ovarian follicule.
The post ovulation follicule is called the corpus lutuem, and it secretes progesterone.
What is the effect of progesterone release?
Progesteronen release by the corpus luteum supresses FSH and LH back to basal levels.
Eventually the corpus lutuem degrades and progesterone levels fall back to baseline. FSH is no longer inhibited, allowing the cycle to begin again.
Typically, a cycle takes 1 month.
What is the relationship between ageing and fertility?
There is a dramatic decline in fertility throughout the lifespan. It gradually declines from birth until menopause, where it will sharply drop.
99% of oocytes developed in the female fetus are lost at birth. Throughout live, follicles which do not ovulate during each menstrual cycle are apoptosed. Only 0.1% of follicles will ever ovulate.
What are the risks accompanied by older age of pregnancy?
- Implantation failure/ difficulty
- Higher rates of embryo abnormality and aneuploidy
- Pre-eclampsia (onset of high blood pressure), gestational diabetes, labour complications, postpartum haemorrhage
- C-section and assisted delivery
- Premature birth, perinatal mortality
- Impaired myometrial contractile function in labour
How is the early transition phase of the menopause characterised?
39-43 years: transition begins
Elevated FSH in the follicular phase
No change in LH, E2 and P4 – may fluctuate more
Regular menstrual cycles
How is the late phase of menopause characterised?
- Irregular / anovulatory cycles
- 3-5 yrs to final menstrual period (FMP)
- decreasing progesterone, coninciding with increasing interval between cycles
- ↑ LH and FSH
- 1-2 years before the final menstrual period, oestrogen begins to decline rapidly
Define menopause
12 consecutive months without a period
What is the median age of menopause?
51.4yrs
This is signficantly lowered by smoking.
With currently life expectancies, post menopausal life span is around 40%
What are the symptoms of menopause?
Dramatic changes in hormones are associated with many symptoms and phsyiological consequences.
Hot flushes - caused by LH surge without large oestrogen increase. Hot flushes are due to a resetting and narrowing of temperature regulation systems within the body.
Psychological symptoms: mood swing, cognitive and memory problem, sleep disturbances
Decreased bone mass: loss of oestrogen is associated with dramatic loss of bone mass (15%)
Increased risk for CVD
Increased fat mass
Urinary frequency, dysuria, incontinence
What is the story of oestrogen replacement therapy?
In the 60s it was believed to be protective against the CVD risk associated with menopause. It is derived from the urine of pregant female horses.
Oestrogen replacement therapy alone was associated with increased risk for endometrial cancer. However, addition of synthetic progesterone compounds was thought to mitigate this risk, while retaining protective effects of ORT.
A large scale study however showed increased risk of ↑ risk and incidence of coronary heart disease, stroke, pulmonary embolism, venous thrombosis, invasive breast cancer, dementia.
It showed a small increase in mineral bone density, but that’s all.
Overview of the male reproductive axis
Hypothalamus secretes gonadotrophin releasing hormone in pulses, which diffuses through the portal veins to the gondatrophs in the anterior pituitary.
Gonadotrophs secrete LH and FSH in pulses. These diffuse through the blood to their targets, the Leydig and Sertoli cells in the Testes.
The testes secrete testosterone, oestrogen, and inhibin.
LH and Testosterone reach their peak at 9:30am.
Testosterone is locally converted to oestrogen by aromatase, playing an important role in the feedback system.
What is the function of HPG regulation in males?
Formation and maturation of spermatogenic cells.
How do sperm and spermogenesis change with age?
Sperm production, sperm count, % normal morphology and viability decline steadily - 30% decline over 50 years
Conception difficulties, lower pregnancy and live birth rates. Even with assisted reproduction where normal morphological sperm are selected, these risks still persist.
Change in sexual activity (duration of abstinence effects sperm concentrations), alcohol and smoking may affect fertility by altering semen quality
