Hormonal control of reproductive processes Flashcards
What are the biological characteristics of Hormonal Control? (6)
- Physiological regulators
- Effective in minute quantities
- Synthesized by cells which may or may not be located in a distinct gland
- Secreted and transported into bloodstream
- Act on specific target cells (presence of receptors)
- Trigger specific responses
What does GnRH stand for?
Gonadotropin releasing hormone
What is the Structure of GnRH?
single chain of 10AA
What happens when GnRH is taken orall?
it gets digested
What is GnRH used for?
- Fertility treatment
- Cryptorchidism
- Non-steroidal contraceptive -nasal spray
What are the 6 hypothalamus hormones regulating reproduction?
- Prolactin-inhibiting hormone (PIH)
- Prolactin-releasing hormone (PRH)
- Gonadotropin releasing hormone (GnRH) From Ventromedial nucleus
- Gonadotropin releasing hormone (GnRH) From Anterior hypothalamic area
- Oxytocin
- Melatonin
What are the neural pathways and principle functions of Prolactin-inhibiting hormone (PIH)?
Neural Pathways:
- Neurons containing dopamine in the arcuate nucleus
Principle Functions:
-Inhibits prolactin release
What are the neural pathways and principle functions of Prolactin-releasing hormone (PRH)?
Neural Pathways:
- Neurons containing dopamine in the arcuate nucleus
Principle Functions:
- Stimulates prolactin release
What are the neural pathways and principle functions of Gonadotropin releasing hormone (GnRH) From Ventromedial nucleus?
Neural Pathways:
- Negative feedback from gonads
Principle Functions:
- Stimulates tonic release of FSH and LH
What are the neural pathways and principle functions of Gonadotropin releasing hormone (GnRH) From Anterior hypothalamic area
Neural Pathways:
- Hypothalamic cells sensitive to estrogen, touch receptors in skin and genitalia of reflex ovulating species.
Principle Functions:
- Stimulates preovulatory surge of FSH and LH
What are the neural pathways and principle functions of Oxytocin?
Neural Pathways:
- Tactile sensations from the mammary gland, uterus and cervix
Principle Functions:
- Induces uterine contractions, milk letdown, and facilitates gamete transport
What are the neural pathways and principle functions of Melatonin
Neural Pathways:
- Retina via retinohypothalamic fibres
Principle Functions:
- Inhibits gonadotropic activity in long-day breeders eg: hamster
- Stimulates the onset of the breeding season in short-day breeders eg: sheep
What is the structure of LH?
It is a glycoprotein
- chain of AA linked together
- Chain of CHO linked to polypeptides
- 2 chains (1 alpha 1 beta) of similar size linked
What does LH target?
Leydig cells
What must be joined for LH to be active?
The alpha and beta residues
What are the characteristics of alpha subunits?
AA sequences are similar between hormones within species
What are the characteristics of beta subunits?
AA sequence is diverse
What is the structure of FSH?
- Glycoprotein with alpha and beta subunits
- CHO content relatively high compared to LH
What does FSH target?
Sertoli cells
What are some monosacharides (charbohydrate chains)
- Mannose
- Galactose
- Fucose
- Glucosamine
- Galactosamine
- Sialic acid
What are charbohydrate chains made of?
polysaccharide units
What is sialic acid essential for?
- biological activity
- extending the half life
How are steroid hormones transported? why?
Bound to proteins in the blood (albumin or globulin) cause they are lipophillic
How are protein hormones transported?
Can travel through blood without being bound to anything cause they are hydrophillic
What does proloctin target?
Leydig cells and sex glands
What does proloactin do?
Works as a facillitator
What is the structure and source of FSH?
Structure: Glycoprotein
Source: Gonadotropes in anterior lobe
What is the structure and source of LH?
Structure: Glycoprotein
Source: Gonadotropes in anterior lobe
What is the structure and source of Prolactin?
Structure: Protein
Source: Mammatropes in anterior lobe
What is the structure and source of Oxytocin?
Structure: Protein
Source: Stored in posterior lobe of pituitary
What are the principle functions of FSH?
- Stimulates follicular growth in female
- Stimulates spermatogenesis in male
What are the principle functions of LH?
- Stimulates ovulation and luteinization of ovarian follicles (corpus luteum) in female
- Stimulates testosterone secretion in male
What are the principle functions of Prolactin?
Promotes lactation and maternal behaviour
What are the principle functions of Oxytocin?
Stimulates contractions of pregnant uterus and causes milk ejection
Where are reproductive steroid hormones produced?
In the testes, ovaries and adrenal cortex
What are steroid hormones made from? (Primarily)
Cholesterol
What happens if a steroid hormone is ingested?
It is effective as it enters the blood stream instead of being digested.
What are two types of prostaglandins?
- PGE2
2. PGF2 alpha
Where were prostaglandins first isolated from?
From sex glands fluid of the prostate
Where are prostaglandins secreted?
Most body tissues
What is the general structure of a prostaglandin?
They are unsaturated fatty acids with 20 C and a cyclopentene ring.
Must have methyl group and carboxyl group at either end of the carbon chain
What prostaglandin is the major luteolitic hormone?
PGF2 alpha
How long is the half life of a prostaglandin?
Very Short
What steroid hormones are secreted by reproductive structures? Which ones are they secreted by?
- Estrogen - theca interna of the ovarian follicle
- Progesterone - corpus luteum
- Testosterone - leydig cells in the testes
What are the functions of estrogen?
- Promotes sexual behaviour
- Stimulates development of secondary sex characteristics
- Anabolic effects
What are the functions of progesterone?
- Works synergistically with estrogen to promote estrous behaviour
- Prepares reproductive tract for implantation
What are the functions of testosterone?
- Develops and maintains accessory sex glands
- Stimulates secondary sexual characteristics
- Stimulates sexual behaviour
- Stimulates spermatogenesis
- Possess anabolic effects
What are the protein hormones produced by reproductive organs? Where are they produced?
- Relaxin - corpus luteum
- Prostaglandin F2 alpha - secreted by most body tissues
- Activins - follicular fluid in female and rete testes fluid in male
- Inhibins - serotonin cells in male and granules a cells in ovary of female
- Follistatin - ovarian follicular fluid in female
What are the functions of relaxin?
- Dilation of the cervix
2. Causes uterine contractions
What are the functions of prostaglandin F2 alpha?
- Causes uterine contractions assisting in sperm transport in female tract and parturition
- Causes regression of corpus luteum
What are the functions of activins?
- Stimulates FSH secretion
What are the functions of inhibins?
- Inhibits FSH secretion to a level which maintains species specific ovulations
Where are reproductive steroid hormones produced?
In the testes, ovaries and adrenal cortex
What are steroid hormones made from? (Primarily)
Cholesterol
What happens if a steroid hormone is ingested?
It is effective as it enters the blood stream instead of being digested.
What are two types of prostaglandins?
- PGE2
2. PGF2 alpha
Where were prostaglandins first isolated from?
From sex glands fluid of the prostate
Where are prostaglandins secreted?
Most body tissues
What is the general structure of a prostaglandin?
They are unsaturated fatty acids with 20 C and a cyclopentene ring.
Must have methyl group and carboxyl group at either end of the carbon chain
What prostaglandin is the major luteolitic hormone?
PGF2 alpha
How long is the half life of a prostaglandin?
Very Short
What steroid hormones are secreted by reproductive structures? Which ones are they secreted by?
- Estrogen - theca interna of the ovarian follicle
- Progesterone - corpus luteum
- Testosterone - leydig cells in the testes
What are the functions of estrogen?
- Promotes sexual behaviour
- Stimulates development of secondary sex characteristics
- Anabolic effects
What are the functions of progesterone?
- Works synergistically with estrogen to promote estrous behaviour
- Prepares reproductive tract for implantation
What are the functions of testosterone?
- Develops and maintains accessory sex glands
- Stimulates secondary sexual characteristics
- Stimulates sexual behaviour
- Stimulates spermatogenesis
- Possess anabolic effects
What are the protein hormones produced by reproductive organs? Where are they produced?
- Relaxin - corpus luteum
- Prostaglandin F2 alpha - secreted by most body tissues
- Activins - follicular fluid in female and rete testes fluid in male
- Inhibins - serotonin cells in male and granules a cells in ovary of female
- Follistatin - ovarian follicular fluid in female
What are the functions of relaxin?
- Dilation of the cervix
2. Causes uterine contractions
What are the functions of prostaglandin F2 alpha?
- Causes uterine contractions assisting in sperm transport in female tract and parturition
- Causes regression of corpus luteum
What are the functions of activins?
- Stimulates FSH secretion
What are the functions of inhibins?
- Inhibits FSH secretion to a level which maintains species specific ovulations
What are the functions of Follistatin?
Modulates the secretion of FSH
How do steroid hormones get into the cell and create products?
They diffuse through the cell membrane (no receptors needed) and into the nucleus where it binds to a receptor.
How do protein hormones get into the cell? Does it enter the nucleus?
Hormone binds to receptor on cell membrane and is actively transported across. Some enter the nucleus, other work in the cytoplasm.
What is the basic structure of a G Protein Coupled receptor?
- 7 trans-membrane domains
- G protein coupled
- normally linked with adenilate cyclase (AC)
What does a G Protein Coupled Receptor usually convert and to what?
Converts ATP to cAMP
What are the most common pathways for a G Protein Coupled Receptor?
Protein kinase A or C pathways
- Phosphorylation and/or transcription
Where are steroid receptors located?
Nuclear or cytoplasmic (normally nuclear)
What are steroid receptors associated with?
Chaperone proteins
What is the role of a chaperone protein?
- protect molecule
- prevent receptor from entering the nucleus before binding
What is a CRE?
cAMP responsive element
What is a CREB?
cAMP responsive element binding protein
What is a CBP?
Co-activator binding protein
What is a TIC?
Transcription initiation complex
What is a TATA box?
a region close to the transcription site that helps initiate the start of transcription.
What are the transcription factors for a cAMP Promoter Region
CRE CREB CBP TIC TATA box
What are the transcription factors for a steroid promoter region?
HSP SRE SRC TIC TATA box
What is a HSP?
Heat shock protein
What is a SRE?
Steroid response element
What is a SRC?
steroid response co-activator
