Lecture 2 - Reproductive Endocrinology Flashcards
Hormone
a substance produced by glands that is transported by the blood to exert a specific effect upon another organ
4 chemical classes of reproductive hormones
- peptides
- glycoprotein
- steroids
- prostaglandins
Peptides
- repro hormone
- aa building blocks connected by peptide bonds
- Gonadotropin Releasing Hormone (GnRH)
- small and easy to be degraded
Glycoprotein
- repro hormone
- 2 protein units: alpha subunit which is common among hormones and beta subunit which is unique for each hormone
- complex and specific
- need ALL components to interact with receptors and be recognized
Steroids
- repro hormone
- lipid of origin: cholesterol
- enzymatic conversions convert cholesterol into a steroid via a pathway
Steroid pathwya
Cholesterol
Pregnenolone
Progesterone
Testosterone
Estradiol
Prostaglandins
- repro hormone
- PFG2aplha and PGE2
Hydrophobic - lipid hormones
-steroids and prostaglandins
-needs carrier proteins in blood
-pass right through cell membrane to ceptors inside
Hydrophilic - protein hormones
-peptides and glycoproteins
-free in blood
-plasma membrane bound receptors
Steps of action for protein hormones
- hormone receptor binding
- G protein activation
- adenylate cyclase activation
- protein kinase activation
- synthesis of new product
Steroid hormone action
- steroid transport- piggy back onto carrier proteins
- movement through the cell membrane, cytoplasm, and nuclear membrane
- binding of steroid to nuclear receptor
- mRNA and protein synthesis
5 sources of repro hormones
- hypothalamus
- pituitary
- gonads
- uterus
- placenta
Gonadotropin Releasing Hormone (GnRH)
Class: neuropeptide
Target: anterior pit
Action: FSH and LH release
FSH
Class: glycoprotein
Target: sertoli cells in testis, granulosa cells in ovary
Action: sertoli fxn (male), follicle growth and E2 synthesis
LH
Class: glycoprotein
Target: leydig cells of testis, theca & luteal cells of ovary
Action: testosterone syn (male), ovulation and progesterone syn (females)
Prolactin
Class: protein
Target: mammary glands
Action: lactation and maternal behaviour
Hormone released from the anterior pituitary
- FSH
- LH
- Prolactin
Oxytocin
Class: neuropeptide
Target: testicular tissue, uterus and mammary
Action: sperm transport; uterine contractions and mammary cell growth
Herring bodies
store oxytocin in postier pituitary until release dictated by hypothalamus
Two cell types of anterior pituitary
- Gonadotroph cells = FSH and LH produced
- Lactotroph cells = prolactin produced
2 ovary hormones
E2 and P4
Estradiol
class: steroid
target: hypothalamus, repro tract, mammary gland
action: increase sexual behaviour, GnRH production and uterine activity as well as mammary development
Progesterone
class: steroid
target: hypothalamus, uterine endothelium, myometrium, mammary gland
action: pregnancy maintenance = decrease sexual behaviour, GnRH production, and uterine activitity; lactation
Testosterone
class: steroid
target: hypothalamus, repro tract, muscle
action: male sexuality! increase sexual behaviour and muscle development, decrease GnRH, spermatogenesis
2 hormones produced in the uterus
Prostaglandin E2 and Prostaglandin F2alpha
Prostaglandin E2
class: prostaglandin
target: ovary
action: increase progesterone production
Prostaglandin F2alpha
class: prostaglandin
target: ovary, uterine myometrium
action: decrease progesterone production, uterine contractions
Hormone produced in placents
Progesterone (some species) and Equine chorionic gonadotrophin
Progesteron
class: steroid
target: hypothalamus, uterine endothelium & myometrium, mammary gland
Action: pregnancy maintence! decrease sexyal behaviour, GnRH production, uterine activity; lactation
Equine chorionic gonadotropin
class: glycoprotein
target: ovary
action: maintains progesterone production
Pineal gland
- above the hypothalamus btw hemispheres of the brain
- sensitive to environmental light and change in photoperiod
- releases melatonin in response to dark = regulates breeding activitiy in seasonal breeders (ex. sheep, goals, horses)
