Reproduction (year 2) Flashcards
how is GnRH released from the hypothalamus?
in pulses
where are the specific receptors that GnRH binds to?
anterior pituitary
what affect will giving a pulsatile dose of a GnRH agonist have?
stimulate FSH and LH release
if GnRH agonists are released continuously what effect will they have?
receptor downregulation and inhibits FSH and LH release
how are GnRH agonists administered?
injection or implants
what are the main uses of GnRH agonists?
stimulate ovulation to improve conception rates and improve synchronisation
suppress reproductive function, induce infertility in males dogs and ferrets
what is the name of the drug used to induce infertility in male dogs?
deslorelin implant
name some warnings of GnRH agonists
pregnant women shouldn’t administer it as it can be absorbed through skin
describe the mechanism of action of GnRH vaccines
two doses of the vaccine given two weeks apart that induce antibodies against GnRH
how are GnRH vaccines administered?
injection
what are GnRH vaccines used for?
chemically castrate pigs
what are the warnings for GnRH vaccines?
do not administer if pregnant, can disrupt reproductive function
where are gonadotropins released?
anterior pituitary
name the 4 gonadotropins used in order of increasing half life
LH, FSH, hCG, eCG
what is the mechanism of action of gonadotropins?
stimulate the release of sex steroid hormones from the testis and ovaries via LH/FSH receptor agonists
what is the route of administration of gonadotropins?
injection
what are gonadotropins used for?
FSH - promote follicle recruitment in super ovulation programmes
hCG - promote follicule maturation, ovulation and CL formation and stimulate testosterone production (rig test)
name the gonadal steroid receptor agonists and antagonists
oestrogens, progestogens, androgens, anti-androgens
name the only licensed oestrogen receptor agonist
estriol
how are oestrogens administered
orally
name the uses of estriol
treat urethral sphincter incompetence, the reproductive effects are unwanted
how are progesterone receptor agonists administered?
injection, implant, orally
what are the effects and uses of progestogens?
inhibit GnRH release, prolongs the luteal phase of the oestrus cycle and inhibits reproductive behaviour. They are used in oestrus synchronisation, suppression of oestrus and to chemically castrate dogs
what are some adverse effects of progestogens?
endometritis, pyometra, increased thirst/appetite, acromegaly, diabetes
what is the only licensed progesterone receptor antagonist?
aglepristone in dogs
what type of antagonist is aglepristone?
competitive
how are progesterone receptor antagonists administered?
injection
what are progesterone receptor antagonists used for?
misalliance and abortion induction
what are the effects of endogenous androgen receptor agonists?
masculinisation, increase libido, increased spermatogenesis, increased protein synthesis
what is the route of administration of androgens?
injection
give an example of an androgen receptor agonist
nandralone
what are androgens used for?
for anabolic effects where excessive tissue breakdown has occurred or where excessive tissue repair is needed
what are the side effects of androgens?
premature closure of growth plates, masculinisation, infertility, inhibit normal GnRH release
give some examples of androgen receptor antagonists
osaterone and delmadinone acetate
what are androgen receptor antagonists used for?
treating prostatic hyperplasia and male hyper sexual behaviour
how are androgen receptor antagonists administered?
orally
what are some side effects of androgen receptor antagonists?
feminisation, PUPD, increased appetite, glucocorticoid effects
what are prolactin antagonists used for?
inhibit lactation and treat false pregnancy in bitches
what is the route of administration for prolactin antagonists?
orally
what are the side effects of prolactin antagonists?
induce luteolysis (abortion)
how are oxytocin receptor agonists administered?
parenterally (peptides broken down by GI)
what are the main uses of oxytocin receptor agonists?
stimulate uterine contraction, promote uterine involution, promote milk let down, aid passage of retained placenta
what tissue is effective at removing prostaglandin receptor agonists from the body?
lungs
how are prostaglandin receptor agonists administered?
parenterally
what are prostaglandin receptor agonists used for?
synchronise oestrus and induce abortion/parturition
what is melatonin used for?
slow release implants in sheep, increases GnRH pulsatility and return to seasonal oestrus to advance the breeding season
how are beta 2 adrenergic agonists administered?
parentally
what are beta 2 adrenergic receptors used for?
relax uterus in cattle to delay delivery, aid manoeuvres, caesarean, replace prolapses, during embryo transfer
what are the adverse effects of beta 2 adrenergic agonists?
tachycardia and tremors
what are glucocorticoids used for and how are they administered?
mimic foetal cortisol surge to induce parturition/abortion. By injection
list some side effects of glucocorticoids
decrease milk yield, suppress of injury/infection response, Cushings, osteoporosis, diabetes, muscle wasting, oedema, GI ulceration, laminitis, abortion, hyperglycaemia
