Reproductive and Endocrine Pharmacology Flashcards
List the major classes of reproductive drugs
GnRH agonists, vaccines Gonadotrophin- anterior pituitary hormones Gonadal steroid receptor agonists and antagonists Androgen agonists/antagonists Prolactin inhibitors Oxytocin receptor agonists Prostaglandin receptor agonists Melatonin B2-adrenergic agonists Glucocorticoid
What is the mechanism of action of GnRH agonists?
Given in pulsatile will stimulate release of FSH and LH
Continuous release agents will cause receptor down regulation and inhibit LH and FSH
What is the mechanism of action of GnRH vaccine?
Two doses of GnRH analogue-protein conjugate to induce antibodies against GnRH
What is the mechanism of action of Gonadotrophins?
LH/FSH receptor agonists
What is the mechanism of action of gonadal steroid oestrogen/progesterone receptor?
Oestrogen receptor agonist
Progesterone receptor agonist
What is the mechanism of action of prolactin inhibitors?
Stimulates growth and differentiation of mammary tissues and initiates milk secretion
What is the mechanism of action of oxytocin receptor agonists?
Normally stored/released from posterior pituitary, binds to myoepithelial cells of mammary gland, the uterus and brain
How are GnRH agonists and vaccine administered?
Agonists- injectable or implants
Vaccine- injectable
How are gonadotrophin administered?
Injection
How is gonadal steroid oestrogen/progesterone receptors administered?
Oestrogen- oral administration
Progesterone- injectable, implant, oral
How are gonadal steroid antagonist blockers administered?
Injection
How is androgen agonists and antagonists administered?
Agonists- injection
Antagonists- oral
How are prolactin inhibitors administered in dogs?
Oral
How are oxytocin receptor agonists administered and prostaglandin?
Parenterally both
How is melatonin, B2 adrenergic and glucocorticoids administered?
Melatonin- implant
B2- adrenergic- parenteral
Glucocorticoid- injection
When would GnRH agonists be used?
In cows to stimulate ovulation
Mares to improve conception and provide synchronisation
In male dogs and ferrets suppression of reproductive function and infertility
What is the the GnRH vaccine used for?
Induce antibodies against GnRH for chemical castration of pigs (prevent boar taint)
What are gonadotrophin used for?
FSH/PMSG (pregnant mares serum gonadotrophin) promotes recruitment of follicles for super ovulation
HCG can promote maturation of follicle, ovulation and formation of the CL
In males stimulates testosterone to see if testicular tissue is present
What is gonadal steroid oestrogen receptor used for?
Estridiol- short acting to treat urethral sphincter incompetence- not repro
What is gonadal steroid progesterone receptor/agonists used for?
Inhibits GnRH release
Prolongs luteal phase of oestrus inhibits repro behaviour
Oestrus synchronisation in cattle and pigs
Suppress oestrus in small animals
Chemically castrate dogs
What are gonadal steroid antagonist blockers used for?
Misalliance and induction of abortion
What are androgen agonists used for?
Weak androgen-receptor agonists used for anabolic effects- tissue breakdown, anaemia from renal disease
What are prolactin inhibitors used for?
Inhibits lactation- false pregnancies in bitches
What is oxytocin receptor agonist used for?
stimulation of uterine contraction to facilitate a fully dilated cervix, promote passage of retained placenta in control of post partum haemorrhage
Promotion of milk ‘let down’ and to facilitate stripping out of infected quarters in mastitis of cow
What is prostaglandin used for?
Used to synchronise oestrus and induce abortion/parturition
What is melatonin used for?
Returns to seasonal oestrus cycling in sexual mature sheep (to advance breeding season)
What are B2 adrenergic agonists used for?
Relax the uterus in cattle In heifers to delay delivery for preparation of soft birth canal To aid malpresentation For caesarean Prevent night-time delivery To facilitate prolapsed uterus During embryo transfer
What are glucocorticoids used for?
Mimics foetal cortisol surge inducing parturition
What drugs should not be administered by pregnant women and why?
GnRH agonists can be absorbed through skin
GnRH vaccine- self injection can disrupt repro function
Gonadotrophin- disturb foetal development
Gonadal steroid antagonist blockers
Oxytocin receptor agonists
Prostaglandin
What potential side effect can gonadal steroid oestrogen receptor cause?
5-9% bitches swollen vulva, swollen mammary gland
Vomiting has been observed
What are potential side effects of gonadal steroid progesterone receptor/agonist?
Endometrial hyperplasia Endometritis Pyometra Increased thirst appetite Induce diabetes mellitus
What can occur if gonadal steroid antagonists blockers are given after day 20 of gestation?
Abortion accompanied with physiological signs of parturition
What type of animals should androgen agonists not be used on and why?
Immature animals, can cause premature closure of growth plates
Inhibits normal secretion of GnRH causing infertility or low sperm count
What are the side effects of androgen antagonists?
reduced ACTH secretion (regulates cortisol), increased appetite, PUPD feminisation
What side effects can oxytocin agonists cause?
cause/complicate uterine dystocia
What side effects can prostaglandin have?
Induction of abortion or parturition may increase dystocia, foetal mortality, placenta retention, metritis
When should melatonin not be used?
If sheep are excessively dirty or wet
What are the potential side effects of glucocorticoids?
Decreased milk yield Retained placenta Suppression of response to injury Cushings Osteoporosis
