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72 Cards in this Set
- Front
- Back
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What is MIF and where does it come from?
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Mullerian Inhibiting Factor
- prevents Mullerian duct from becoming uterus and fallopian tubes - produced by Sertoli cells |
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What structures does the Wolffian duct turn into, and under what stimulus?
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- stimulated by testosterone
- epididymis, seminal vesicles, vas deferens |
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What structures do the urogenital sinus and tubercle turn into, and under what stimulus?
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- stimulated by DHT (dihydrotestosterone)
- penis, urethra, prostate, scrotum [testosterone also inhibits them from becoming female external genitalia] |
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What stimulates fetal Leydig cells to make T?
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- chorionic gonadotropin, which has LH-like activity
- produced by embryonic syncytiotrophoblasts [in females, CH stimulates luteal progesterone] |
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What is ABP?
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Androgen-binding protein
- holds testosterone within seminiferous tubules at a high concentration to support development of germ cells - produced by Sertoli cells |
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What is found in the interstitium between seminiferous tubules?
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- Leydig cells (produce T)
- peritubular myoid cells (produce PmodS, a protein that stimulates Sertoli cell function) - fibroblasts, blood, lymph |
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Sertoli, myoid, and Leydig cells are equivalent to what cells in the female reproductive system?
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Sertoli ~ granulosa cells (FSH receptors)
Myoid ~ theca externa cells Leydig ~ theca interna cells (LH receptors) |
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What is IGF-3 and where is it produced?
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- stimulates descent of testes after birth in some animals
- produced by Leydig cells [IGF-1 and IGF-2 from liver] |
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What is the physiologic function of [normal levels of] PRL in males?
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- potentiate actions of LH on Leydig cells by modulating LH receptor number and sensitivity
- increase androgen receptors on prostate and seminal vesicles |
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What is the result of hyperprolactinemia in males?
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Decreased GnRH -> decreased LH and FSH -> testicular atrophy
[PRL is not physiologically an inhibitor of GnRH, only in pathologic conditions.] |
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What is the function of estrogen in the rete testis?
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Fluid reabsorption (sperm concentration)
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What is the major urinary estrogen of the stallion?
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Estrone
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What are inhibins and where are they produced?
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Inhibins A and B
- proteins produced by Sertoli cells - stimulate T production by Leydig cells - feed back negatively on pituitary output of FSH (but not LH!) and possibly hypothalamic GnRH [anti-estrogen] |
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What is activin and where is it produced?
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- protein produced by Sertoli cells
- stimulates FSH production - inhibits T production by Leydig cells [pro-estrogen] |
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What is follistatin?
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FSH-suppressing protein that binds activin
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What hormones are required for spermatogenesis?
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FSH and testosterone
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What is SHBG (sex-hormone binding globulin)?
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- circulating protein produced by the liver
- similar structure to ABP produced by Sertoli cells (but ABP does not circulate) - binds testosterone and estrogen |
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How are testosterone, estrogen, and progesterone transported in blood?
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Testosterone:
- 60% SHBG (sex-hormone binding globulin) - 37% albumin Estrogen: - 60% albumin - 37% SHBG Progesterone - 50% transcortin (CBG, cortisol binding globulin: binds cortisol and progesterone with equal affinity) - 45% albumin |
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Why do testosterone levels rise during puberty?
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Hypothalamus begins to lose its sensitivity to low levels of testosterone, so higher levels of T are required for neg feedback to suppress GnRH.
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What is the relationship between leptin and GnRH during puberty?
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Leptin is produced by adipocytes.
Stimulation of leptin receptors in the hypothalamus -> increased GnRH -> increased LH and FSH |
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Accessory sex glands of the dog, cat/camelid, other?
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Dog: prostate
Cat/Camelid: prostate, bulbourethral (Cowper's) gland Other: prostate, bulbourethral gland, seminal vesicle |
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What do the seminal vesicles (vesicular glands) produce?
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- fructose
- Vit C - AAs (5) - prostaglandins - phosphorylcholine - fibrinogen - inositol - ergothionine - activating principal - flavins |
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What is the molecule used as a screen for benign prostatic hyperplasia (BPH) and prostate cancer?
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PSA: prostate-specific antigen
- a serine endopeptidase |
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What is the function of the prostate?
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- adds bicarb to semen to enhance sperm motility (acidity suppresses motility) and to neutralize acidic vaginal secretion
- contains clotting enzymes to form coagulum, which makes it easier to ejaculate the semen - also contains profibrinolysin, which dissolves coagulum in female repro tract so sperm are more free to swim |
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What is required for sperm capacitation?
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- enzyme activation: hyaluronidase and proteases in acrosomes of sperm
- destruction of decapacitation factor found in semen - secretions of uterus, oviduct, maybe follicular fluid |
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What is involved in erection?
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Parasympathetic Nervous System
- e.g. ACh, NO, VIP endothelial-derived relaxation factor (EDRF) -> cGMP (or cAMP) -> relaxation |
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How does viagra work?
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cGMP phosphodiesterase inhibitor
(erection will be maintained as long as there is cGMP or cAMP around) |
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How do you remove the masculinizing effect of testosterone (or related steroids) while maintaining the anabolic effect?
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remove oxygen at C3 (important for androgenic activity)
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Effects of E2 on the uterus during the preovulatory phase
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- increased synthesis of E2, progesterone, and oxytocin receptors
- increased protein synthesis - increased straight uterine endometrial ducts - increased blood supply (but no coiling of blood vessels) |
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Effects of E2 on the cervix
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- increase opening of os (mouth of the uterus)
- increase alkaline mucus secretion |
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Effects of E2 on mammary glands
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- increased fat deposition and stromal tissue
- growth of ductular system (not lobuloalveolar development: that is progesterone) - increased prolactin in humans and dogs |
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Effects of E2 on bone
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- accelerates late pre-pubertal growth, then closes epiphyseal plates
- decreased PTH sensitivity / increased CT sensitivity -> increased osteoblastic activity - widens pelvis for head of fetus |
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Effect of E2 on bladder's internal sphincter
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- upregulate activity of alpha-1 receptors -> keep sphincter closed
- use to treat urinary incontinence |
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Effect of E2 on erythropoiesis
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- impairs erythropoiesis
[testosterone increases erythropoiesis] |
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Relationship between body temperature and stage of estrus cycle
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- progesterone tends to shunt blood towards internal organs, whereas estrogen tends to cause peripheral vasodilation
- so pre-ovulatory period (estrogen-dominant) body temperature is lower than post-ovulatory (progesterone-dominant) |
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Effects of E2 on the liver
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- increased plasma protein synthesis: steroid-binding globulins (CBG, SHBG), thyroid-binding globulin, angiotensinogen, coagulation factors (fibrinogen and prothrombin), albumin
- increased LDL receptor synthesis -> lower plasma cholesterol [shared action with T4 and insulin] |
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Why can birth control pills lead to coagulopathy?
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- they contain both estrogen and progesterone
- progesterone -> increased liver production of fibrinogen - estrogen -> increased production of both fibrinogen and prothrombin |
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Effects of progesterone on uterine endometrium and myometrium
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- increase glycogen content
- increase alkalinity - increase vascularity - decrease uterine contractions (maintain gestation) - increase beta:alpha adrenergic receptors in myometrium (keeps smooth muscle relaxed) - decrease estrogen endometrial receptors - increase branching and coiling of uterine glands - decrease immune competence (to retain fetus) - decrease endometrial COX activity (otherwise endometrium would produce prostaglandins that would terminate pregnancy) |
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Effects of progesterone on cervix
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- form thick, tenacious, cellular mucus
- form cervical plug: seals fetus off from outside environment, establishes conditions unfavorable for penetration and survival of sperm |
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Effects of progesterone on mammary glands
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- development of lobules and alveoli
- increased water retention -> swelling of breasts during luteal phase of menstrual or estrous cycle |
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Effects of progesterone on the kidneys
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Progesterone competes with aldosterone for mineralocorticoid receptors in the distal tubules.
Progesterone is less potent than aldosterone. - if not pregnant: progesterone prevents aldosterone from exerting its full effect -> natriuresis - if pregnant: increase in both progesterone and aldosterone, so increased Na retention -> increased ECF volume |
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Effects of progesterone on respiratory center
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- increased depth of respiration, tidal volume, respiratory minute volume
- decreased expiratory and inspiratory reserve - no change in respiratory rate or vital capacity |
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What is the minipill and what does it do?
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Low levels of progesterone
- create cervical plug, which prevent sperm/bacteria from entering uterus - may not inhibit LH secretion / ovulation |
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What is depo provera and what does it do?
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High levels of progesterone
- inhibit GnRH pulse frequency and therefore LH secretion - block ovulation - mimic pregnancy |
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What is epostane and what does it do?
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Inhibits progesterone synthesis by inhibiting 3-beta-hydroxysteroid dehydrogenase, which is the enzyme that turns pregnenolone into progesterone
- since progesterone has such a short half-life, continuous secretion is required to maintain pregnancy; disrupting the synthesis of progesterone for just a little while will induce uterine contractions and abortion - terminates unwanted early pregnancy in bitches and queens |
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What is RU-486 (Mifegyne or Mifepristone) and what does it do?
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Blocks progesterone receptors
- administered with prostaglandins - used in bitches but not queens because the feline progesterone receptor may lack the Gly needed for RU-486 to bind to the receptor |
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Proposed functions of pre-ovulatory estrogen (in the absence of progesterone)
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- positive feedback on GnRH -> LH surge -> ovulation
- increased libido - sensitize anterior pituitary to GnRH - sensitize ovaries to gonadotropins - re-epithelialize endometrial surface following menstruation (in primates) |
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What cells release pre-ovulatory estrogen? Post-ovulatory?
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Pre-ovulatory: theca cells make precursors, but granulosa cells turn them into estrogen
Post-ovulatory: theca cells release estrogen (granulosa cells release progesterone) |
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What does the fertility pill contain?
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hCG (human chorionic gonadotropin)
- multiple ovulations -> potentially multiple births |
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What do you give for FSH activity in various animals?
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- can give eCG (equine chorionic gonadotropin, aka PMSG, pregnant mare's serum gonadotropin) to induce follicular growth and ovulation in various domestic animals
- in mares, PMSG has luteinizing effect, so for FSH effect, must give equine adenohypophyseal extract or FSH-rich human menopausal gonadotropin (hMG) |
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Which species do not have placental lactogen?
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pigs, rabbits, dogs
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What protein hormone has the highest concentration in maternal circulation during the second half of pregnancy?
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placental lactogen (PL)
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Actions of placental lactogen
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PRL-like effects:
- maintain luteal progesterone production (in some animals) - develop mammary glands - CNS stimulation of maternal behavior GH-like effects: - decrease maternal use of glucose and AAs; increase transport across placenta for fetus - increase use of FFAs by mother - decrease maternal responsiveness to insulin - increase maternal EPO production (increase RBC mass) |
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Which compounds are transported across the blood-brain barrier to increase maternal behavior?
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PL and/or PRL
(carrier-mediated transport across BBB of choroid plexus) |
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Which species are short-day breeders?
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Sheep and goats
(melatonin just doesn't inhibit their gonadal activity) |
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What is unique about the bovine estrous cycle?
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- short period of estrus (<1 day)
- ovulation occurs 18 hours after onset of estrus - FSH waves during diestrus (so follicle development and regression occurs in waves) |
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What is unique about the equine estrous cycle?
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- estrus is long, so metestrus is contained within, and mare ovulates during estrus (24-48 hrs before end of estrus)
- LH is still rising when ovulation occurs (in other animals, ovulation follows LH surge) |
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What is unique about the canine estrous cycle?
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- seasonally monoestric / diestric
- ovulation occurs 2-3 days following onset of estrus (about 12 hrs after LH peak) - bitch continues to accept males for days following ovulation - no post-ovulatory estrogen peak or waves - CL survives/secretes progesterone for 50-70 days whether or not pregnancy occurs (no luteolytic factors-- CL dies only due to age) |
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What is unique about the feline estrous cycle?
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- seasonally polyestrous; induced ovulators
- ovulation occurs 24-50 hrs after mating |
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What is unique about the rodent estrous cycle?
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- estrous cycle lasts 4-6 days
- progesterone rises at the same time as LH during proestrus (in other animals, progesterone rises following LH peak) - pregnancy lasts 21 days - mating stimulus induces twice-daily PRL surges for 8-10 days that keeps CL alive for progesterone output |
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What things are actively transported from the dam to the fetus?
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- calcium
- iron - phosphate - amino acids - water-soluble vitamins - essential polyunsaturated long-chain FAs |
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What things are transported from dam to fetus by receptor-mediated endocytosis?
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immunoglobulins, but only in some animals
(other animals get them through colostrum) |
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What things move from dam to fetus via diffusion?
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- glucose, VFAs, KBs
- electrolytes - oxygen - carbon monoxide - glycerol - fat-soluble vitamins |
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What things move from fetus to dam via diffusion?
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Waste products:
- CO2 - urea, uric acid - creatinine - unconjugated bilirubin |
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What glucose transporters are in the placenta?
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GLUT-1 and GLUT-3
[since there are no Na-dependent glucose transporters, glucose cannot be moved against its concentration gradient] |
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In which species is the fetal and adult hemoglobin the same?
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Horses and pigs
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Which hormones are essential for lactation?
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Pituitary lactogenic complex:
- PRL - oxytocin - ACTH - ADH Others: - cortisol - aldosterone - insulin |
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How do catecholamines inhibit milk ejection?
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- block oxytocin release
- vasoconstrict mammary arterioles to reduce available oxytocin - antagonize the action of oxytocin on mammary myoepithelial cells |
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What factors decrease PRL output?
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- dopamine (L-DOPA, bromocriptine)
- serotonin (stimulates DA release) - GAP (GnRH-associated peptide) - GABA (PRL --> GABA, so neg feedback loop) - primary hyperthyroidism (excess T4 decreases TRH, which may decrease PRL) |
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What factors increase PRL output?
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Suckling:
- VIP (vasoactive intestinal polypeptide) - endorphins (decrease DA) - oxytocin and ADH Others: - primary hypothyroidism (loss of neg feedback --> excess TRH --> PRL) - increased light exposure - in dogs, estrogen during pregnancy increases PRL |
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Which animals experience lactational anestrus, and which do not?
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Anestrus: beef cows, sows, cats, dogs
Little suppressive effect from lactation: dairy cows, goats, sheep, horses |
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Does the fetal liver utilize KBs? Neonatal liver? Adult liver?
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Fetal liver does use KBs, but neonatal and adult does not.
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