2 - Reproductive Endocrinology Flashcards
What is a hormone
Substance produced by one or more gland that is transported by the blood to exert a specific effect upon another organ
What are hormone receptors
Tissues targeted by a specific hormone have receptors for that hormone
Four classes of repro hormones
- Peptides
- Glycoproteins
- Steroids
- Prostaglandins
What is a peptide hormone
Chain of amino acids linked by peptide bonds
Peptide bonds are made of…
carbon and ammonia
What are glycoprotein hormones
An alpha and a beta subunits held together by non-covalent hydrogen bonding and van der Waals forces
What are steroids
Hormone with four carbon rings
The steroid pathway involves multiple occurrences of what process?
Enzymatic conversion
Conversion of steroid to estradiol
Cholesterol -> pregnenolone -> progesterone -> testosterone -> estradiol
Differences between steroid conversion in males vs females
Males do not produce estradiol (ends at testosterone)
What are prostaglandins
Lipids with 20C
Two major prostaglandins in repro phys
Prostaglandin F2 alpha
Prostaglandin E2
Hormone action requires…
the presence of specific receptors on the target
Slide 12
Hormone and target tissue figure
What kind of receptors do protein hormones use?
Plasma membrane bound receptors
Five steps of action of protein hormones
- Hormone-receptor binding
- G-protein activation
- Adenylate cyclase activation
- Cyclic AMP activates protein kinase
- Synthesis of new product (protein)
slide 14***figure
What kind of receptors do steroid hormones use
Diffuse into the cell and attach to specific nuclear receptors
Steps of action of steroid hormones
- Steroid transport - “piggy back” on protein
- Movement through the plasma membrane, cytoplasm and nuclear membrane
- Binding of steroid to nuclear receptor
- mRNA and protein synthesis
Slide 16***figure
Five sources of reproductive hormones
- hypothalamus
- pituitary (anterior & posterior)
- Gonads (ovary & testis)
- Uterus
- Placenta
Bone around the pituitary gland is called…
Sella turcica
Hypothalamus is attached to the anterior pituitary via…
Stalk and portal vessels
What does the anterior pituitary release? Posterior?
Anterior = releasing hormones
Posterior = oxytocin
What is the hormone released by the hypothalamus (its chemical class, its target tissue and its action)
Gonadotropin releasing hormone (GnRH)
Class: neuropeptide
Target tissue: Anterior pituitary
Action: release of FSH & LH from anterior pituitary
Name the three hormones released by the anterior pituitary
Follicle stimulate hormone (FSH)
Luteinizing hormone (LH)
Prolactin
What are the chemical classes and target tissues of FSH, LH, and prolactin
FSH = glycoprotein. Target sertoli cells of testis and granulosa cells of ovary
LH = glycoprotein. Target leydig cells of testis and theca/luteal cells of ovary
Prolactin = protein. Targets mammary glands
Action of FSH
Spermatogenesis in testis
Follicle growth and estradiol synthesis in ovary
Action of LH
Testosterone synthesis
Ovulation an progesterone synthesis
Prolactin action
Lactation and maternal behaviour
What hormone is released by the posterior pituitary (class, target tissues, action)
Oxytocin
Class: neuropeptide
Target tissues: Testicular, uterus & mammary
Action: sperm transport, uterine contractions, mammary cell growth
When does oxytocin help in females
Parturition, expel retained placenta
What are the gonadotropins? Where are they released? Go to…
FSH & LH
Released by gonadotroph cells in anterior pituitary
Go to gonads
What cells release prolactin? Go to…
Lactotroph cells
Go to mammary gland
What are herring bodies
Store oxytocin until release in posterior pituitary
What hormones are released by the ovary? Classes
Estradiol (steroid)
Progesterone (steroid)
Target tissues of estradiol and progesterone
E: hypothalamus, reproductive tract, mammary gland
P: hypothalamus, uterine endothelium & myometrium, mammary gland
Action of estradiol? Progesterone?
E: sexuality (increase sexual behaviour, GnRH production, uterine activity. Mammary development)
P: pregnancy maintenance (decrease sexual behaviour, GnRH production, uterine activity. Lactation)
What hormone is released by the testis? Chemical class, target tissues, action
Testosterone
Class: steroid
Target tissues: hypothalamus, reproductive tract, muscle
Action: sexuality (increase sexual beh, muscle development. Decrease GnRH production. Spermatogenesis)
What hormones are released by the uterus? Chemical class?
Prostaglandins (E2 and F2 alpha)
Target tissues and action of prostaglandin E2 and F2 alpha
E2: ovary, increase progesterone production
F2: ovary and uterine myometrium. Decrease progesterone production. Uterine contractions (parturition)
What hormones are released by the placenta? Classes
Progesterone (some spp; steroid)
Equine chorionic gonadotropin (glycoprotein)
Target tissue and action of progesterone from the placenta
TT: hypothalamus, uterine endothelium & myometrium, mammary gland
Action: pregnancy maintenance (decrease sexual beh, gnRH production and uterine activity. Lactation)
Target tissues and action of Equine chorionic gonadotropin
TT: ovary
Action: maintains progesterone production
Hormone used for pregnancy detection in horses
Equine Chorionic Gonadotropin (eCG)
Where is the pineal gland located?
Above the hypothalamus between the hemispheres of the brain
Pineal gland is sensitive to… and releases…
environmental light and senses changes in photoperiod
releases melatonin in response to dark
Pineal gland via melatonin regulates what?
Breeding activity in seasonal breeders
