Pituitary Gland Pathology

Question 1

What is autocrine signalling?

Answer 1

Hormones are on the cell itself

Question 2

What is an endocrine gland?

Answer 2

Organs/ Glands comprised of cells that synthesise, store, secrete and release signalling molecules into the blood

Question 3

What in cells makes polypeptides/ glycoproteins?

Answer 3

Ribosomes and the ER

Question 4

What is the primary site of action for polypeptide hormones?

Answer 4

The plasma membrane as they are H2O soluble

half life = minutes

Question 5

What is the basis of steroid hormones?

Answer 5

Cholesterol based so they are lipid soluble- can diffuse through the cell membrane

T 1/2 = hours

function as nuclear receptors and transcription factors

Question 6

What are catecholamines derived from?

Answer 6

Tyrosine derived

Question 7

How is the pituitary formed embryologically?

Answer 7

Rathke’s pouch- they come together to form different parts of the pituitary

Question 8

What are the two key concepts surrounding pituitary function?

Answer 8

• the anterior pituitary produces most of the endocrine TROPHIC hormones in the body
• the production of these hormones is under the control of releasing and inhibitory hormones produced by the hypothalamus

Question 9

What three types of cells are in the pars distalis?

Answer 9

• acidophils- peptides
• basophils- glycoproteins
• chromophobes- corticotrophs

Question 10

What cell type is in the pars intermedia?

Answer 10

Chromophobes

proopiomelanocortin-> ACTH, a-MSH, b-endorphins

Question 11

What is the function of releasing hormones?

Answer 11

Stimulates the release of trophic hormones

Question 12

What is the function of inhibitory hormes?

Answer 12

Inhibits the release of trophic hormones

Question 13

What two hormones are produced by the posterior pituitary gland?

Answer 13

• Oxytocin
• ADH

Question 14

What is the function of oxytocin?

Answer 14

Stimulates contraction of
myometrium, myoepithelium of
mammary gland

Question 15

What is the function of ADH?

Answer 15

• Stimulates the insertion of aquaporins into the renal tubule epithelia
• increases urine osmolarity
• decreases plasma osmolarity
• arteriolar vasoconstriction

Question 16

What is primary hyperfunction of the pituitary

Answer 16

• usually hypersecretion of a hormone
• typically neoplastic

Question 17

What is secondary hyperfunction of the pituitary?

Answer 17

• increased trophic or releasing hormones
• or a decrease in inhibitroy hormones (more likely)

Question 18

What is primary hypofunction of the pituitary?

Answer 18

• Destruction, lack of formation of the secretory cells or a deficiency in the synthesis of the hormone

Question 19

What is Juvenile panhypopituitarism

Answer 19

Failure of oropharyngeal ectoderm to differentiate into the
adenohypophysis

autosomal recessive inheritance

primary hypofunction

Question 20

What is juvenile panhypopopiturasim most common in?

Answer 20

German shephards

Question 21

What does failure of proper pituitary development result in?

Answer 21

prolonged gestation and abnormal adrenal function

Question 22

What is the hypophyseal form of central diabetes?

Answer 22

inadequate secretion of ADH
* occurs due to destruction of the neurohypophysis
* compression from anterior pituitary masses

Question 23

What kind of hormones do acidophils secrete?

Answer 23

Peptide hormones

Question 24

What kind of hormones do basophils secrete?

Answer 24

glycoproteins

Question 25

What kind of hormones do chromophobes secrete?

Answer 25

Variable

Question 26

What dog breed is juvenile panhypopituitarism most common in?

Answer 26

German Shephards

Question 27

What is the Gross Pathology of Juvenile Panhypopituitarism?

Answer 27

* Normal until around 2 months * Slow growth/ Retention of 'puppy hair' * Fox or Coyote like * Delayed epiphysis closing * lack of genital development

Question 28

What does failure of proper pituitary development and signalling typically result in?

Answer 28

Prolonged gestation and abnormal adrenal function

Question 29

What are the two ways you can get failure of foetal endocrine function?

Answer 29

* Genetic (aplasia of the adenohypophysis) * Toxic (malformations of the CNS) including the hypothalamus

Question 30

What does Cyclopamine (toxic principle in corn lillies) do to the CNS?

Answer 30

inhibits neural tube devlopment via impaired sonic hedgehog signalling

Question 31

What is synopthalmia and what plant causes it?

Answer 31

* Clinical abnormality where both eyes are fused and can be seen centrally in the middle of the face * Caused by corn lillies

Question 32

What causes the hypophyseal form of DI neurohypophysis?

Answer 32

* Destruction of the neurohypophysis * Compression from anterior pituitary masses

Question 33

What causes the nephrogenic form of DI neurophyophysis?

Answer 33

* Inability to respond appropriately to ADH * occurs during kidney damage, rarely inherited

Question 34

What is the Clinical Presentation of DI neurohypophysis?

Answer 34

* Excretion of large volumes of hypotonic urine * administration of ADH can be used to differentiate between hypophyseal and nephrogenic

Question 35

What is the most common cause of cortisol excess in dogs?

Answer 35

Adenohypophysis adenoma | ACTH-secreting adenoma

Question 36

What is a somatotroph?

Answer 36

GH secreting adenoma

Question 37

What may a nonfunctional adenoma do?

Answer 37

may destroy the remaining pituitary gland via compression, resulting in trophic atrophy of target organs

Question 38

What does equine Pituitary Pars Intermedaite dysfunction do?

Answer 38

Nodular hyperplasia and neoplasia of the pars intermedia | increases the PI hormones

Question 39

What is the pathogenesis of Equine Pituitary Pars Intermedia dysfunction?

Answer 39

* Degeneration of hypothalamic dopaminergic neurons * Loss of inhibition on the PI * Hypertrophy/ hyperplasia * Compression of the overlying hypothalamus

Question 40

What is Hypophysitis?

Answer 40

Inflammation of the pituitary gland

Question 41

What are some examples of polypeptides/ Glycoproteins?

Answer 41

* GH, PRL, ACTH, ADH, oxytocin

Question 42

What are some examples of Steroids?

Answer 42

* Cortisol * Androgens * Aldosterone

Question 43

Where do catecholamines/ iodothyronines act?

Answer 43

Act at plasma membrane surface or intranuclear | have a variable half ife

Question 44

What are some examples of catecholamines?

Answer 44

epinephrin, norepinephrin, thyroxine

Question 45

What is secondary hypofunction?

Answer 45

When the pituitary produces a decreased amount of a trophic hormone

Question 46

What does the failure of pituitary development look like in cattle?

Answer 46

aplasia of the adenohypophysis

Question 47

What does corn lily do to the CNS?

Answer 47

* malformation of the CNS including the hypothalamus * Cyclopamine is the toxic principle * inhibits neural tube development via sonci hedgehog signalling

Question 48

What is the nephrogenic form of DI?

Answer 48

Inability to respond appropriately to ADH occurs due to kidney damage- rarely inherited

Question 49

What is the clinical presentation of the nephrogenic form of DI?

Answer 49

* excretion of large volumes of hypotonci urine (polyuria) with increased drining (polydipsia) * administration of exogenous ADH

Question 50

What is the most common cause of systemic cortsiol excess in dogs?

Answer 50

Cortocotroph adenoma | they must demonstarte metastasis ## Footnote to be classified as pituitary carcinoma

Question 51

What is the sequelae to corticotroph?

Answer 51

adrenal cortical hyperplasia

Question 52

What does a somatotroph cause?

Answer 52

* Acromegaly (too much GH) * reported in dogs, cats and sheep

Question 53

What is hypophysitis?

Answer 53

inflammation of the pituiatry gland