Neurohypophysis
hypothalamusÀÇ supraoptic nucleus & paraventricular nucleusÀÇ large cell body¿¡¼ »¸¾î
³ª¿À´Â axonÀ¸·Î Çü¼ºµÇ¸ç µÎ°¡Áö È£¸£¸óÀ» »ý¼ºÇÑ´Ù.
i) arginine vasopressin(AVP) = ADH
ii) oxytocin
AVP´Â renal tubule¿¡ ÀÛ¿ëÇÏ¿© water retention, urine concentrationÀ» ÀÏÀ¸Å°°í
oxytocinÀº suckling½Ã postpartum milk letdownÀ» ÀÚ±ØÇÑ´Ù.
AVP deficiency´Â DI¸¦ ÀÏÀ¸Å°°í AVP excess or inappropriate productionÀº hyponatremia,
water retentionÀ» ÀÏÀ¸Å²´Ù.
oxytocin deficiency or excess¿Í °ü·ÃÇÑ clinical disorder´Â ¾Ë·ÁÁø °ÍÀÌ ¾ø´Ù.
Vasopressin
1) ÀÛ¿ë Fig 329-2
collecting tubule cell surfaceÀÇ G protein-coupled V2 receptor¿¡ °áÇÕÇÏ¿©
adenylate cyclase¸¦ activation(cAMP¡è)½ÃŲ´Ù.
±× °á°ú aquaporin 2¶ó´Â ´Ü¹éÁú·Î ÀÌ·ç¾îÁø water channelÀÌ apical membraneÀ¸·Î
À̵¿ÇÏ°Ô µÈ´Ù.
cf. aquaporin 2 water channel : apical membrane
aquaporin 3, 4 : basal-lateral surface
tight junction: unregulated water flow¹æÁö
°í³óµµÀÇ AVP´Â ¸î°¡Áö ´Ù¸¥ ÀÛ¿ëµµ ÀÖ´Ù.
i) skin, GI blood vesselÀÇ smooth muscle contraction
ii) liver glyogenolysis
iii) CRF(corticotropin-releasing factor)¿¡ ÀÇÇÑ ACTH release potentiation
À§ÀÇ ÀÛ¿ëÀº V1a or V1b receptor¿¡ ÀÇÇØ Á¶ÀýµÇ¸ç phospholipase C¿Í °ü·ÃÀÖ´Ù.
2) ÇÕ¼º
polypeptide precursorÀÇ ÇüÅ·ΠÇÕ¼ºµÇ´Âµ¥ ¿©±â¿¡´Â neurophysin II¶ó´Â binding protein°ú
copeptinÀ̶ó´Â glycosylated peptide°¡ Æ÷ÇԵȴÙ.
´Ù¸¥ peptide hormone°ú ¸¶Âù°¡Áö·Î »õ·ÎÀÌ ÇÕ¼ºµÈ AVP-neurophysin II precursor´Â
axonÀ» Ÿ°í À̵¿ÇÏ¿© AVP, neurophysin II, copeptinÀ¸·Î ³ª´©¾îÁø´Ù.
neuronÀÌ ÀڱصǸé CaÀÌ À¯ÀԵǾî neurosecretory vesicleÀÌ ÇÕÃÄÁ® AVP°¡ systemic
circulationÀ¸·Î ¹æÃâµÈ´Ù.
3) ºÐºñ
* ºÐºñÁ¶Àý
i) "effective" osmotic pressure - 1Â÷Àû Á¶ÀýÀÎÀÚ
supraoptic nucleus±ÙóÀÇ anteromedial hypothalamus¿¡ À§Ä¡ÇÑ osmoreceptors¾Ë·ÁÁø
specialized cells¿¡ ÀÇÇØ controlµÈ´Ù.
ÀÌ osmoreceptor´Â plasma sodium or mannitol°ú °°Àº soluteÀÇ Á¶±×¸¸ º¯È¿¡µµ ¹Î°¨
ÇÏ´Ù.
plasma osmolality/sodiumÀÌ ¡280 mosmol/kg or 135 meq/LÀÌÇÏ·Î depressµÇ¸é
water diuresis¸¦ ÀÏÀ¸Å°±â À§ÇØ plasma AVP´Â ¾ïÁ¦µÈ´Ù.
¹Ý´ë·Î plasma osmolality/sodiumÀÌ ¡295 mosmol/kg and 143 meq/LÀÌ»óÀÌ µÇ¸é
maxium antidiuresis¸¦ ÀÏÀ¸Å°±â À§ÇØ AVP´Â Áõ°¡ÇÑ´Ù.
ii) baroregulation - minor importance
AVP secretionÀº blood volume or pressureÀÇ acute change¿¡µµ ¿µÇâÀ» ¹Þ´Â´Ù.
baroregulation˼ cardiac atria, aorta, carotid artery˂ transmural pressure receptors
¿¡¼ ±â¿øÇÑ neuronal afferents¿¡ ÀÇÇØ ÁÖ·Î Á¶ÀýµÈ´Ù.
baroreceptor -> vagus & glossopharyngeal nerve
-> brain stemÀÇ nucleus tractus solitarisus
-> hypothalamusÀÇ paraventricular & supraoptic nucleii
ÀÌ pathway´Â blood volume or pressure°¡ 10-20%ÀÌ»ó °¨¼ÒÇÒ ¶§ tonic inhibitory toneÀ»
À¯ÁöÇÔÀ¸·Î½á AVP release¸¦ Á¶ÀýÇÑ´Ù.
iii) other nonosmotic variables: nausea, hypoglycemia, glucocorticoid deficiency,
smoking, and, possibly, hyperangiotensinemia
¿¹> nausea -> medullaÀÇ emetic center¸¦ ÅëÇÏ¿© AVP ºÐºñ¸¦ ÀÚ±ØÇÏ¿©
plasma AVP°¡ 50-100¹è Áõ°¡
4) ´ë»ç
´ëºÎºÐ °£°ú ½ÅÀåÀ» ÅëÇÏ¿© degradationµÇ¸ç ¹Ý°¨±â´Â 10-30ºÐ Á¤µµ µÈ´Ù.
urinary AVP excretionÀÇ ÃøÁ¤Àº plasma AVP ºÐºñ º¯ÈÀÇ reliable indicator°¡ µÇÁö ¸øÇÑ´Ù.
ÀÓ½ÅÁß¿¡´Â placenta¿¡¼ N-terminal peptidase¸¦ »ý¼ºÇÔÀ¸·Î½á metabolic clearance°¡
3-4¹è Áõ°¡ÇÑ´Ù.