reproductive endocrinology Flashcards
Lactation
Baby affects mothers metabolism by feeding
*Mammogenesis: development of mammary gland occurs during pregnancy
*lactogenesis: lactation function, initiated near the time of parturition
*galactopoiesis: maintenance or enhancement of established lactation
see diagram for breast tissue:
1) prior to pregnancy
2) early
3) mid pregnancy (4 months)
4) after birth during weaning
5) after weaning
Mammary gland development is controlled by changing hormones
*Mammary gland at birth: mostly lactiferous ducts (few alveoli)
*At puberty: lactiferous ducts sprout and branch. Further menstrual cycles cause limited ductal lobular-alveolar growth
*During early pregnancy: hypertrophy of ductal-lobular-alveolar system takes place
*Prominent lobules form & lumina of alveoli become dilated. Certain growth factors are important under control of mammogenic hormones
*mid-pregnancy: differentiation of alveolar cells. By end of 4th month gland fully developed, awaits endocrine changes for activation
see diagram of lactating tissue: milk protein and fat globules collect in alveoli
It is possible to continue breast feeding indefinitely
- Two weeks of breast feeding provides immune benefits
- 12 weeks of feeding supports baby and reduces mothers risk of breast cancer
- Not breastfeeding at all results in return to normal within 6 weeks – purperium with potential to get pregnant again in 6-8 weeks
-Pharmacological methods can induce purperium faster e.g. for mothers who miscarry
A changing oe/prog ratio & prl initiate & maintain milk secretion
*breast milk is a rich source of energy & nutrients
*colostrum: secreted during 1st week. Less fat & lactose than mature milk but greater amount of protein, minerals, fat-sol vitamins & IgGs
*Transitional milk follows
*After 12 months baby needs to be weaned as it will require iron
lactogenesis to galactopoiesis
(see diagram)
*During a transitional phase concentrations of IgG & total proteins decline, while lactose, fat & calorific value increase to yield mature milk
*After parturition prolactin levels fall. If they are to remain high & full lactation to continue stimulation by suckling needed
*Having produced milk it must be “let down” to deliver to infant: MER
*Can be conditioned response –
seeing a photo of your baby, hearing a baby scream can stimulate milk letdown
Contraceptive effect of breast feeding
*return of menstrual cycle in 6 weeks of delivery in non-nursing mothers
*nursing mothers: amenorrhoea for 25-30 weeks (can’t get pregnant ~1.5 years, 18-24 months)
*prolactin inhibits
*GnRH
*action of GnRH on pituitary
*action of gonadotrophins on ovaries
Sexual dysfunction
Male dysfunction
*Erectile dysfunction
*Priapism - erection maintained will not go away
*Normal erectile function requires a complex set of dynamic neural and vascular interactions. Conditions affecting these systems may impair erectile function.
Female dysfunction
Inability to achieve orgasm – less treatable
Mechanism of erection
(A)In flaccid state, arterial vessels constricted & venous vessels non-compressed.
(B)Erection- smooth muscle relaxation in trabeculae & arterial vasculature cause increased blood flow, rapidly filling & dilating cavernosal spaces. Venous outflow drops as expanding cavernosal spaces compress venous plexus & larger veins of tunica albuginea.
(see diagram for molecular mechanisms)
Causes of erectile dysfunction
*Vasculogenic - conditions that affect the flow of blood to the penis.
*Neurogenic - conditions that affect the nervous system.
*Hormonal
*Anatomical
*Pharmacological - interfering chemicals e.g. antidepressants
*Psychological - e.g. performance anxiety
it is a spinal reflex so will be affected by spinal injury
Treatments for erectile dysfunction
*Diagnosis-consider cause and any underlying health disorders
*Treatment should be suitable for the individual
*Lifestyles changes
*Diet, exercise – for diabetes type 2 or obesity
*Drug treatments
*Vacuum devices
*Surgically implanted devices e.g. abdominal pump
*Sex therapy for psychological causes
Fineline pharmacotherapy for erectile dysfunction
PDE-5 inhibitors:
*sildenafil- Viagra
*tadalafil- Cialis
*vardenafil – Levitra
Mode of action:
Inhibit breakdown of cGMP by phosphodiesterase causes inc cGMP in corpus cavernosum and inc vasodilation
Causes a near natural effect
Not suitable for people on nitrate medication, or with heart disease – resulting in reflex tachychardia (and death)
Rapidly absorbed and broken down in ~4 hours
(see diagram)
Second-line pharmacotherapy
(before viagra used vasodilatory injection)
*Intracavernosal or intraurethral alprostadil (PGE1)
*Vasodilatory effects on corpora cavernosa
- rapid arteriolar inflow & expansion of lacunar spaces within the corpora.
- corporal sinusoids compressed against tunica albuginea, venous outflow impeded , penile rigidity develops
- Corporal veno-occlusive mechanism.
Priapism – prolonged painful erection >4hrs is a medical emergency
Causes:
*Blood disorders
*Prescription medicine
*Recreational drug use
*Injury
*Metabolic diseases
*Blood clots
*Black widow spider bites
Treatment depends on cause:
*Low flow ischemic priapism
*High flow
*Aim to reduce morbidity and to restore sexual function
*Pharmacotherapy
*Surgery - cut to penis to drain blood
