Neuroendocrinology Flashcards
What are neuroendocrine cells?
Neurosecretory cells that release signal molecules from their synaptic terminals into the blood
What controls neuroendocrine cells?
Sympathetic transmission from presynaptic neurons
What are the steps in development of the pituitary gland?
Evagination of the floor of third ventricle
Evagination of the oral ectoderm
Rathkes pouch is pinched off
Merge
What is the neural ectoderm?
Evagination of the floor of the third ventricle
What is rathke’s pouch?
Evagination of oral ectoderm
What do parvocellular nuclei do?
Release hormones to the capillaries of median eminence
Where do the median eminence capillaries come from?
Superior hypophysial artery
Where do the capillaries of medial eminence lead to?
Portal veins to the anterior pituitary
What do hormones released from the parvocellular nuclei do?
Regulate endocrine secretion from the anterior pituitary
What do the magnocellular nuclei do?
Project to posterior pituitary and release hormones to the capillaries supplied by the inferior hypophysial artery
Where are the hormones stored in the posterior pituitary gland?
Hypothalamic neuron terminals
When/ where are oxytocin and vasopressin released?
Under neural control into hypophysial capillaries -> inferior hypophysial vein
What increases growth hormone secretion?
GH releasing hormone
Ghrelin
Where is GH releasing hormone secreted?
Hypothalamic parvocellular neuroendocrine cells
What secretes ghrelin?
Endocrine cells of the stomach
What is the other function of ghrelin? (Ie not growth hormone stimulator)
Powerful appetite stimulator
What is growth hormone secretion decreased by?
GH inhibiting hormone
Where is GH inhibiting hormone secreted from?
Hypothalamic parvocellular neuroendocrine cells
What is another term for GH inhibiting hormone?
Somatostatin
What is the GH negative feedback controlled by?
GH already in circulation
IGF-1 in circulation (released by the liver in response to GH)
What does IGF-1 inhibit?
Hypothalamus and pituitary gland
What does GH do in adipose tissue?
Increases lipolysis
What does GH do in liver tissue?
Increases gluconeogenesis and IGFs
What does GH do in muscle tissue?
Increases protein synthesis
What does IGF release lead to?
Increase in somatic cell growth, chondrocyte function and bone modelling/ remodelling
What does IGF stand for?
Insulin growth factor
What do GH levels look like throughout the day in young adults?
Small peaks in the day and a huge spike in the middle of the night
What happens to the GH levels throughout the day in older adults?
Same as young adults just smaller peaks
How does your mean circulating GH conc change throughout life?
Increases after birth, constant through childhood, peaks in puberty and then slowly decreases as you age
What is is called when you have an excess of GH?
Acromegaly
What is acromegaly generally caused by?
Pituitary adenoma
What are the metabolic consequences of acromegaly?
Excess GH -> insulin resistance
Impaired glucose tolerance and hyperinsulinaemia
Possibly also dyslipidaemia
