
TY  - JOUR
A1  - Peterson, A. J. 
A1  - Ledgard, A. M. 
A1  - Hodgkinson, S. C. 
T1  - The proteolysis of insulin-like growth factor binding proteins in ovine uterine luminal fluid
JF  - Reproduction, Fertility and Development
JO  - Reprod. Fertil. Dev.
Y1  - 1999
VL  - 10
IS  - 4
SP  - 309
EP  - 314
KW  - 
UR  - https://doi.org/10.1071/R98034 
N2  - During days 12&#8211;15 after oestrus (day 0), the uterine luminal fluid (ULF) of both pregnant and non-pregnant ewes contains only two prominent insulin-like growth factor binding proteins (IGFBPs) of 16&#8211;18 kDa and 22&#8211;24 kDa which preferentially bind IGF-2. Immunoblotting with an IGFBP-3 antibody revealed these to be proteolytic fragments of IGFBP-3. In contrast, the ULF from anoestrus and ovariec-tomized ewes contained intact IGFBP-3 (40&#8211;44 kDa) and IGFBP-2 (34 kDa). Co-incubation of ULF from an anoestrus ewe with that from a day 12 cycling ewe cleaved the IGFBP-3 present into the two lower molec-ular weight IGFBPs characteristic of ewes in the late luteal phase of the oestrous cycle. The variation in pro-teolytic activity both during the year and during the cycle suggested an influence of progesterone. Supplementation of progesterone to long-term ovariectomized ewes via a CIDR-G&trade; breeding device for 5, 10 or 15 days induced marked proteolytic activity in all 10-day treated sheep. The ULF from the 15-day treated ewes showed reduced activity and could inhibit the activity present in 10-day ULF, suggesting the induction of an inhibitor after prolonged exposure to progesterone treatment. A possible role of IGFBP-3 proteolysis in the ovine ULF may be to selectively increase the bioavailability of IGF-1 in the uterine microenvironment, which may be crucial for the rapid elongation of trophoblast that begins during days 12&#8211;15 after mating. 
ER  -

