LEC 1 - Hypothalamic + Pituitary Hormones Flashcards
What seven hormones are released from the anterior pit.?
ACTH
GH
TSH
PRL
FSH
LH
MSH
What hormones are secreted from the posterior pit.?
ADH
Oxytocin
What is the structure that is responsible for stimulating the pituitary gland?
Hypothalamus
What does the hypothalamus integrate the activities of?
Endocrine + Nervous
What is the endocrine system regulated by?
Pituitary
What is the nervous system regulated by when it comes to the hypothalmus?
Kidney
What is the major difference between anterior and posterior pituitary stimulation?
Posterior is directly stimulated by the hypothalamus
Anterior is stimulated by hormones released by the hypothlamus
What two nuclei are responsible for stimulating the posterior pituitary?
Supraoptic
– and –
Paraventricular
What artery carries the hormones that stimulate the anterior pituitary?
Superior hypophyseal artery
-physis: Pituitary gland
Hypophysis
-physis: Anterior pituitary
Adenohypophysis
-physis: Posterior pituitary
Neurohypophysis
What is the adenohypophysis derived from?
Oral mucosa
What is the neurohypophysis derived from?
Nerual ectoderm
What are the two types of regulatory loops when it comes to regulation of hormones?
Long
and
Short
What makes something a short regulatory loop?
Hormone secreted by the pituitary (or goal hormone) is what negative regulates the hypothalamus
What makes something a long regulatory loop?
A downstream by product of the hormone released is what negatively regulates the hypothalamus
Term: Peptide hormones (Types?)
Chains of AA
Glycoproteins
Short polypeptides/small proteins
What are important glycoproteins?
TSH + LH + FSH
What are important short polypeptides?
ADH
Oxytocin
GH
Prolactin
Insulin
Glucagon
PTH
What are the ways that the peptide hormones work to induce changes in cells?
effect cAMP levels
effect Ca2+ levels
How are cAMP levels affected by peptide hormones?
Stimulate G protein
cAMP is stimulated/inhibited
Affect Kinase levels
Ion channels/Enzymes
What hormones of importants effect cAMP levels?
ADH
FSH
LH
TSH
How do hormones effect the cell in a way that calicum levels change?
Activate G protein receptor
PLC > DAG > PKC
Open calcium channel
Calmodulin activated
What hormone works by changing the calcium levels in the cell?
Oxytocin
What are the characteristics of hormones that work through surface receptors?
Fast acting
Pathways are already present, just increasing or decreasing activity
Term: Lipid dermivatives (Types?)
Carbon rings and side chains
Built from FA’s or cholesterol
Eicosanoids + Steroid
What are the important eicosanoids?
Prostaglandins
What are eicosanoids derivatives of?
Arachodonic acid
What are steroids derivatives of?
Cholesterol
What are the important steroid hormones?
Androgens
Estrogens
Progestins
How do lipid hormones activate changes in the cell?
Diffusion through the membrane
Bind to cytoplasmic receptors
Go to nucleus and cause transcription of new protein
What are the characteristics of steroid hormones?
Induce signals slowly, because creating new signaling pathways
Since different cells have different concentrations of receptors some will take longer to react then others
Term: AA derivatives (Types?)
Small molecules structurally related to individual AA’s
Tyrosine + Tryptophan
What is thyroid hormone made form?
Tyrosine
What are the signs a dog has diabetes insipidus?
Diluted urine
Normal glucose + creatine levels in urine
Increased hematocrit
PU/PD
What are the two froms of DI? Whats wrong in each case?
Central - No ADH
Nephrogenic - Kidneys not responding to ADH
How does ADH regulate water excretion?
Induces aquaporin 2 in the collecting duct
What is the mechanism by which aquaporin is inserted into the collecting duct?
ADH stimulates G protien
Increase cAMP
PKA stimulated
Vesciles taken to membrane
**Aquaporin-3 always expressed
What type of hormone is vasopressin?
Peptide
What are the types of vasopressin?
AVP
LVP (pigs)
DDAVP (drug form)
Characteristics of LVP
From pigs
so shorter duration and smaller response in cats, dogs, and horses
Characteristics of DDAVP
Modified structure to increase response and duration
L-ARG changed to D-ARG
Extra tail of AA added
What is the purpose of desmopressin?
Endogenous vasopressing replacement
In what form is DDAVP given?
Nasal spray
Not well tollerated in this method by animals
So given in conjunctiva - varies between animal
Dose to effect
When is the injectable form of DDAVP given?
when conjunctival isn’t tolerated
Why can oral tablets be given for DDAVP?
Hydrolysis of peptide, doesnt work well
What is the peak effect time in dogs for DDAVP? What is the duration of action?
peak = 2 to 6 hours
Duration = 10 to 27 hours
What is the major side effect of DDAVP?
Increase Factor VIII + vWF
Cause a hypercoagulable state = thormbotic events
What causes acromegaly?
Increased endogenous GH secretion secondary to an active pituitary adenoma
What are the signs of acromegaly?
Systolic cardiac murmur
Hepatomegaly/Renomegaly
PU/PD
Polyphagia w/ weight gain
Diabetic but unresponsive to insulin
Why is there a diabetogenic effect of GH?
GH stimulates liver to break down glcogen into glucose
Fuesl growth effects
How does GH have glucose sparing effect?
Stimulates adipose cells to break down stored fat
Fueling growth effects
What are the two methods to inhibit GH secretion?
Decrease levels of GH-RH
Increase levels of GH-IH
What is released by the liver that causes the growth effects that is stimulated by GH?
IGF-1
Why can’t we increase IGF-1 levels to inhibit GH expression?
Would promote hypoglycemia
What is the drug used to treat acromegaly?
Octreotide
What is octreotide? Type and mechanism
Synthetic, 8aa
Exogenously increases the amount of GH-IH
results in decrease in amount of circulating GH
How so octreotide aborbed and processed?
SC admin
Rapidly absorbed
Need to adjust if patient has renal disease
What is the drug used to increase milk production in cattle?
Somatotropin
What are the other uses for somatotropin other than milk production?
Increase growth rate + improved meat quality in pigs
Increased lean to fat ratio in beef cattle
Pituitary dwarfism in dogs
What type of hormone is somatropin?
peptide
How does somatotropin effect metabolic function?
Increased fat utilization by organs
Increased glycogen hydrolysis
Increased glucose avalible for milk
What does somatropin do in regards to mammary glands? How?
GH > Liver > IGF -1
Increases blood flow (via increased CO)
Increased nutrient extraction
What is the reason for variability in output with milk in cows treated with somatotropin?
Primiparous cows < multiparous cows
Ambient temps
Feed
What is the reaons for a cow to have ketogensis?
Increase engergy demands for lactation not met by diet
Increase utilization of NEFA + conversion to BHB
Enter starvation state reduces production
How can GH reduce ketosis?
Direct effect of decreasign BCS through increased lipolysis/glucose-sparing
Indirect through better feed management
How is somatotropin given?
every 14 days
depot preparation
What is the withdrawl time for somatotropin?
0 day
What are the adverse effects of somatotropin?
Mastitis + Laminitis
DM + Acromegaly in Dogs
Increased rate of twinning
