Evidence that AVP receptors in AtT-20 corticotrophs are not coupled to secretion of POMC-derived peptides.
This study reports the presence in AtT-20 corticotrophs of high affinity-low capacity receptors for arginine-vasopressin (AVP), whose binding capacity was considerably enhanced by the divalent metal ion nickel. These binding sites, when analyzed in the presence of nickel, showed high affinity for AVP, vasotocin and oxytocin, but recognized to a lesser extent the V2-agonist 1-deamino-AVP, as well as V1-antagonists. Surprisingly, AVP failed to alter secretion of proopiomelanocortin (POMC)-derived peptides from the cells or corticotropin-releasing factor (CRF)-induced cAMP synthesis, as reported in normal corticotrophs. Exposure of cells to CRF elicited an increase in mRNAPOMC levels, while, in contrast, AVP was without significant effect. It thus appears that in AtT-20 tumor cells, the AVP receptors are not coupled to either the biochemical or biological cellular response.
Lutz-Bucher
B
B
Institut de Physiologie, UA CNRS 309, Strasbourg, France.
Jeandel
L
L
Heisler
S
S
Roberts
J L
JL
Koch
B
B
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002460:Cell Line; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D008297:Male; D051379:Mice; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011945:Receptors, Angiotensin / Q000378:metabolism*; D017483:Receptors, Vasopressin; D000521:alpha-MSH / Q000378:metabolism*
D012333:RNA, Messenger; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D000521:alpha-MSH; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone