Reproductive and Endocrine Pharmacology

Question 1

List the major classes of reproductive drugs

Answer 1

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

Question 2

What is the mechanism of action of GnRH agonists?

Answer 2

Given in pulsatile will stimulate release of FSH and LH

Continuous release agents will cause receptor down regulation and inhibit LH and FSH

Question 3

What is the mechanism of action of GnRH vaccine?

Answer 3

Two doses of GnRH analogue-protein conjugate to induce antibodies against GnRH

Question 4

What is the mechanism of action of Gonadotrophins?

Answer 4

LH/FSH receptor agonists

Question 5

What is the mechanism of action of gonadal steroid oestrogen/progesterone receptor?

Answer 5

Oestrogen receptor agonist

Progesterone receptor agonist

Question 6

What is the mechanism of action of prolactin inhibitors?

Answer 6

Stimulates growth and differentiation of mammary tissues and initiates milk secretion

Question 7

What is the mechanism of action of oxytocin receptor agonists?

Answer 7

Normally stored/released from posterior pituitary, binds to myoepithelial cells of mammary gland, the uterus and brain

Question 8

How are GnRH agonists and vaccine administered?

Answer 8

Agonists- injectable or implants

Vaccine- injectable

Question 9

How are gonadotrophin administered?

Answer 9

Injection

Question 10

How is gonadal steroid oestrogen/progesterone receptors administered?

Answer 10

Oestrogen- oral administration

Progesterone- injectable, implant, oral

Question 11

How are gonadal steroid antagonist blockers administered?

Answer 11

Injection

Question 12

How is androgen agonists and antagonists administered?

Answer 12

Agonists- injection

Antagonists- oral

Question 13

How are prolactin inhibitors administered in dogs?

Answer 13

Oral

Question 14

How are oxytocin receptor agonists administered and prostaglandin?

Answer 14

Parenterally both

Question 15

How is melatonin, B2 adrenergic and glucocorticoids administered?

Answer 15

Melatonin- implant
B2- adrenergic- parenteral
Glucocorticoid- injection

Question 16

When would GnRH agonists be used?

Answer 16

In cows to stimulate ovulation
Mares to improve conception and provide synchronisation
In male dogs and ferrets suppression of reproductive function and infertility

Question 17

What is the the GnRH vaccine used for?

Answer 17

Induce antibodies against GnRH for chemical castration of pigs (prevent boar taint)

Question 18

What are gonadotrophin used for?

Answer 18

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

Question 19

What is gonadal steroid oestrogen receptor used for?

Answer 19

Estridiol- short acting to treat urethral sphincter incompetence- not repro

Question 20

What is gonadal steroid progesterone receptor/agonists used for?

Answer 20

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

Question 21

What are gonadal steroid antagonist blockers used for?

Answer 21

Misalliance and induction of abortion

Question 22

What are androgen agonists used for?

Answer 22

Weak androgen-receptor agonists used for anabolic effects- tissue breakdown, anaemia from renal disease

Question 23

What are prolactin inhibitors used for?

Answer 23

Inhibits lactation- false pregnancies in bitches

Question 24

What is oxytocin receptor agonist used for?

Answer 24

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

Question 25

What is prostaglandin used for?

Answer 25

Used to synchronise oestrus and induce abortion/parturition

Question 26

What is melatonin used for?

Answer 26

Returns to seasonal oestrus cycling in sexual mature sheep (to advance breeding season)

Question 27

What are B2 adrenergic agonists used for?

Answer 27

``` 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 ```

Question 28

What are glucocorticoids used for?

Answer 28

Mimics foetal cortisol surge inducing parturition

Question 29

What drugs should not be administered by pregnant women and why?

Answer 29

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

Question 30

What potential side effect can gonadal steroid oestrogen receptor cause?

Answer 30

5-9% bitches swollen vulva, swollen mammary gland | Vomiting has been observed

Question 31

What are potential side effects of gonadal steroid progesterone receptor/agonist?

Answer 31

``` Endometrial hyperplasia Endometritis Pyometra Increased thirst appetite Induce diabetes mellitus ```

Question 32

What can occur if gonadal steroid antagonists blockers are given after day 20 of gestation?

Answer 32

Abortion accompanied with physiological signs of parturition

Question 33

What type of animals should androgen agonists not be used on and why?

Answer 33

Immature animals, can cause premature closure of growth plates Inhibits normal secretion of GnRH causing infertility or low sperm count

Question 34

What are the side effects of androgen antagonists?

Answer 34

reduced ACTH secretion (regulates cortisol), increased appetite, PUPD feminisation

Question 35

What side effects can oxytocin agonists cause?

Answer 35

cause/complicate uterine dystocia

Question 36

What side effects can prostaglandin have?

Answer 36

Induction of abortion or parturition may increase dystocia, foetal mortality, placenta retention, metritis

Question 37

When should melatonin not be used?

Answer 37

If sheep are excessively dirty or wet

Question 38

What are the potential side effects of glucocorticoids?

Answer 38

``` Decreased milk yield Retained placenta Suppression of response to injury Cushings Osteoporosis ```