ANTERIOR PITUITARY HORMONES Flashcards
Tumors that have an MIB-1 proliferative index greater than 3%, excessive p53 immunoreactivity, and increased mitotic activity
Atypical pituitary Tumors
Monoclonal antibody that is used to detect the Ki-67 antigen, a marker of cell proliferation, and a high “proliferation index” suggests higher degree of atypia
MIB-1
The enlargement seen during pregnancy is due to
Lactotroph hyperplasia.
Thyrotroph and lactotroph or gonadotroph hyperplasia can also be seen in
Longstanding primary thyroidal or gonadal failure,
Structurally related to prolactin and human placental lactogen
Growth Hormone or somatotropin
Pituitary cells that produce GH, comprise over one-third of normal pituitary weight.
Somatotrophs
GH is considered as __ because it directly influences both anabolic and catabolic processes.
Amphibolic hormone
One major effect of GH is _
Allows an individual to effectively transition from a fed state to a fasting state without experiencing a shortage of substrates required for normal intracellular oxidation
Although GH has direct effects on many tissues, it also has indirect effects that are mediated by factors that were initially called
Somatomedins
Shown to directly play a role in the pathophysiology of several human cancer
IGFBPs and specifically IGFBP-3
upregulate active IGFBP-3 secretion, which inhibits IGF-1 signaled mutagenesis, and, thus, inhibits neoplastic cell proliferation
P53 tumor suppressor gene
Can be associated with high levels of IGF-I, and levels of IGFBP-3 may be inappropri- ately normal in some people with active acromegaly.
Hepatomas
Definitive testing for determining the autonomous production of GH relies upon the normal suppressibility of GH by
Oral glucose loading
Results from pathologic or autonomous GH excess and, in the vast majority of patients, is a result of a pituitary tumor.
Acromegaly
Structurally related to GH and human pla- cental lactogen. Considered a stress hormone, it has vital functions in relationship to reproduction
Prolactin
Considered a polypeptide hormone capable of inhibit- ing prolactin secretion;
Prolactin inhibitory factor (PIF)
Unique among the anterior pituitary hormones because its major mode of hypothalamic regulation is tonic inhibition rather than intermittent stimulation
Prolactin
The only neuroendocrine signal that inhibits prolactin and is now considered to be the elusive PIF
Dopamine
Examples of medications that cause hyperp- rolactinemia include:
Phenothiazines, butyrophenones, metoclopramide, reserpine, tricyclic antidepressants, α-methyldopa, and antipsychotics that antagonize the dopamine D2 receptor
Also directly stimulate lactotrophs to synthesize prolacti
Estrogen
A pituitary tumor that directly secretes prolactin, and it represents the most common type of functional pituitary tumor
Prolactinoma
The principal form of prolactin is a
23-KD peptide
If the 150-kD form of prolactin predominates, this is called
Macroprolactinemia
Are the most commonly used therapy for microprolactinomas.
Dopamine agonists
