The regulation of the corticomelanotropic cell activity in aves. III--Effect of various peptides on the release of MSH from dispersed, perfused duck pituitary cells. Cosecretion of ACTH with MSH.
1. The melanotropin-releasing activity of arginine-vasopressin (AVP), arginine-vasotocin (AVT), oxitocin (OT), mesotocin (MT) and corticotropin-releasing factor (CRF) was studied in the duck using dispersed, perfused pituitary cells and a specific alpha-MSH RIA. 2. Log dose-response curves were obtained for all the peptides ranging from 5 to 100 ng/ml. All peptides behaved as partial agonists compared to duck median eminence extracts (DME). 3. AVT and MT displayed an alpha-MSH releasing capacity of 60% relative to DME whereas all other peptides behaved as weak agonists with less than 15% capacity relative to DME. 4. AVT and CRF when perfused together acted synergistically on alpha-MSH release yielding a dose response line whose slope approximated that of DME. 5. ACTH was cosecreted together with alpha-MSH in all situations studied with an ACTH to alpha-MSH molar ratio of about 10. 6. It is concluded that CRF and neurohypophyseal peptides may be physiological stimulators of both alpha-MSH and ACTH release in aves.
Castro
M G
MG
Centro de Estudios Endocrinos, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
Estivariz
F E
FE
Iturriza
F C
FC
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology; D003346:Corticotropin-Releasing Hormone / Q000502:physiology; D004372:Ducks / Q000502:physiology*; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism / Q000502:physiology*; D010121:Oxytocin / Q000502:physiology; D010455:Peptides / Q000502:physiology*; D010477:Perfusion; D010902:Pituitary Gland / Q000166:cytology / Q000502:physiology*; D011863:Radioimmunoassay; D014668:Vasotocin / Q000502:physiology
D010455:Peptides; D001127:Arginine Vasopressin; D010121:Oxytocin; D000324:Adrenocorticotropic Hormone; D009074:Melanocyte-Stimulating Hormones; D003346:Corticotropin-Releasing Hormone; D014668:Vasotocin