Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias
Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias
Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias
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16 t h International Congress on Animal <strong>Reproduction</strong><br />
106 Poster Abstracts<br />
P235<br />
Prolact<strong>in</strong> Activity Dur<strong>in</strong>g the Follicular Phase <strong>in</strong> the Mare:<br />
Evi<strong>de</strong>nce of an Extra-Pituitary Prolact<strong>in</strong> Source<br />
K<strong>in</strong>g, SS 1 *, Roser, J 2 , Jones, KL 1<br />
1Southern Ill<strong>in</strong>ois University Carbondale, IL; 2 University of California, Davis,<br />
CA<br />
Prolact<strong>in</strong> (PRL) activity <strong>in</strong> the equ<strong>in</strong>e follicle has been documented <strong>in</strong><br />
the form of PRL receptors on the corpus luteum 1 and PRL <strong>in</strong> the<br />
follicular fluid 2 (FF). The objective of this study was to i<strong>de</strong>ntify<br />
locations and possible sources for PRL <strong>in</strong> the follicular phase ovary.<br />
Circulat<strong>in</strong>g PRL concentrations were analyzed from three studies (61<br />
cycles, 17 mares). Plasma PRL was <strong>de</strong>term<strong>in</strong>ed by homologous<br />
double antibody RIA 3 . PRL concentrations around ovulation (0-1d<br />
postovulation) were compared with the early luteal phase (2-10 d).<br />
The granulosa/theca layer was removed postmortem from anonymous<br />
mares (n=10) and stored frozen (-80°C). Equ<strong>in</strong>e pre-PRL mRNA was<br />
extracted and prepared for quantitative PCR us<strong>in</strong>g primers and<br />
reaction conditions previously <strong>de</strong>scribed 4 . Equ<strong>in</strong>e pituitary mRNA<br />
was used to generate a standard curve from which concentrations of<br />
pre-PRL mRNA transcripts were <strong>de</strong>term<strong>in</strong>ed. Presence of PRL <strong>in</strong><br />
ovarian structures was <strong>de</strong>term<strong>in</strong>ed by immunohistochemistry (IHC).<br />
Whole ovaries (n=6) from cycl<strong>in</strong>g mares were fixed <strong>in</strong> 4%<br />
paraformal<strong>de</strong>hy<strong>de</strong>, embed<strong>de</strong>d <strong>in</strong> paraff<strong>in</strong> and cut <strong>in</strong>to 5 um sections.<br />
Sections were <strong>in</strong>cubated with R4 PRL rabbit anti-porc<strong>in</strong>e first<br />
antibody (DL Thompson, Louisiana State Univ) and goat anti-rabbit<br />
IgG-biot<strong>in</strong>ylated (avid<strong>in</strong>-biot<strong>in</strong> complex) second antibody. Sli<strong>de</strong>s<br />
were <strong>de</strong>veloped with DAB chromagen-Ni and countersta<strong>in</strong>ed with<br />
nuclear fast red sta<strong>in</strong>. Equ<strong>in</strong>e pituitary served as a positive control.<br />
Plasma PRL <strong>de</strong>monstrated a short-term (1-2 d) <strong>in</strong>crease (P=0.001)<br />
around ovulation. Equ<strong>in</strong>e pre-PRL mRNA was <strong>de</strong>tected <strong>in</strong> all<br />
granulosa/theca samples <strong>in</strong> concentrations <strong>in</strong>versely correlated to<br />
follicle size (P