Document Detail

Regulation of yolk-androgen concentrations by plasma prolactin in the American kestrel.
MedLine Citation:
PMID:  11716575     Owner:  NLM     Status:  MEDLINE    
The concentrations of maternally derived androgens in the yolks of avian eggs vary within and among clutches, but a mechanistic basis for this variation has not been elucidated. We investigated in the American kestrel, Falco sparverius, whether changes in plasma-prolactin concentrations induced by changes in photoperiod and food supply affect yolk-androgen concentrations. Over the course of a photoinduced breeding period in the laboratory, we measured concentrations of plasma immunoreactive prolactin (ir-prolactin) in female kestrels with ad libitum food availability (control) or food availability that was reduced during the early breeding period. In a second laboratory study, we administered via osmotic mini-pumps ovine prolactin (o-prolactin) to females beginning on the day they laid their first egg of a clutch (egg-day 1) to determine the effects of high prolactin concentrations on yolk-androgen concentrations. In both this study and one on free-living kestrels, we quantified changes in yolk-androgen concentrations with date of clutch initiation. Concentrations of ir-prolactin in nonlaying females rose with date, irrespective of food treatment. Egg-day 1 ir-prolactin concentrations were higher in control females laying late during the breeding phase than in those laying early. This increase was absent in food-reduced females. Yolk-androgen concentrations in eggs 3 and 4 but not eggs 1 and 2 of the clutch were higher in clutches initiated late than in clutches initiated early in the breeding phase in both the field and laboratory. o-prolactin treatment elevated yolk-testosterone but not androstenedione concentrations. These findings suggest that, in American kestrels, seasonal and laying-associated increases in plasma-prolactin concentrations elevate yolk-testosterone concentrations. Food availability and other factors may interact with date to regulate the effects of prolactin on yolk-testosterone deposition.
K W Sockman; H Schwabl; P J Sharp
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Hormones and behavior     Volume:  40     ISSN:  0018-506X     ISO Abbreviation:  Horm Behav     Publication Date:  2001 Dec 
Date Detail:
Created Date:  2001-11-21     Completed Date:  2002-01-22     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0217764     Medline TA:  Horm Behav     Country:  United States    
Other Details:
Languages:  eng     Pagination:  462-71     Citation Subset:  IM    
School of Biological Sciences, Center for Reproductive Biology, Washington State University, Pullman, Washington 99164-4236, USA.
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MeSH Terms
Androgens / metabolism*
Egg Yolk / metabolism*
Oviposition / physiology*
Prolactin / physiology*
Raptors / physiology*
Sex Differentiation / physiology*
Grant Support
Reg. No./Substance:
0/Androgens; 9002-62-4/Prolactin

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