| dc.description.abstract | This research was conducted to test the hypothesis that select nutrients including
glucose, leucine, arginine and glutamine stimulate conceptus development by activating
mTOR (mammalian target of rapamycin; HGNC approved gene name: FRAP1, FK506
binding protein 12-rapamycin associated protein 1) signaling pathway.
First, temporal changes in quantities of select nutrients (glucose, amino acids,
glutathione, calcium, sodium and potassium) in uterine lumenal fluid from cyclic (Days
3 to 16) and pregnant (Days 10 to 16) ewes were determined. Total recoverable glucose,
Arg, Gln, Leu, Asp, Glu, Asn, His, beta-Ala, Tyr, Trp, Met, Val, Phe, Ile, Lys, Cys, Pro,
glutathione, calcium and sodium was greater in uterine fluid of pregnant compared to
cyclic ewes between Days 10 and 16 after onset of estrus. Of note were remarkable
increases in glucose, Arg, Leu and Gln in uterine flushings of pregnant ewes between
Days 10 and 16 of pregnancy.
Second, effects of the estrous cycle, pregnancy, progesterone (P4) and interferon
tau (IFNT) on expression of both facilitative (SLC2A1, SLC2A3 and SLC2A4) and
sodium-dependent (SLC5A1 and SLC5A11) glucose transporters, cationic amino acid
transporters (SLC7A1, SLC7A2 and SLC7A3), neutral amino acid transporters (SLC1A4,
SLC1A5, SLC3A1, SLC6A14, SLC6A19, SLC7A5, SLC7A6, SLC7A8, SLC38A3,
SLC38A6 and SLC43A2) and acidic amino acid transporters (SLC1A1, SLC1A2 and
SLC1A3) in ovine uterine endometria from Days 10 to 16 of the estrous cycle and Days 10 to 20 of pregnancy as well as in conceptuses from Days 13 to 18 of pregnancy were
determined. Among these genes, SLC2A3 and SLC7A6 were detectable only in
trophectoderm and endoderm of conceptuses. The abundance of mRNAs for SLC2A1,
SLC2A4, SLC5A1, SLC5A11, SLC7A1, SLC7A2, SLC1A4, SLC1A5, SLC43A2 and
SLC1A3 changed dynamically in ovine uterine endometria according to day of the
estrous cycle and early pregnancy. Expression of mRNAs for SLC2A1, SLC5A11 and
SLC7A1 in endometria was induced by P4 and further stimulated by IFNT with shortterm
treatment (12 days), while expression of SLC7A1 and SLC1A5 in endometria
required long-term treatment (20 days) with P4 and IFNT.
Third, effects of the estrous cycle, pregnancy, P4 and IFNT on expression of
nitric oxide synthase (NOS1, NOS2 and NOS3), GTP cyclohydrolase (GCH1), ornithine
decarboxylase 1(ODC1), insulin-like growth factor II (IGF2), FRAP1 complexes
(FRAP1, LST8, MAPKAP1, RAPTOR, RICTOR), regulators (TSC1, TSC2, RHEB) and an
effector (EIF4EBP1) of FRAP1 signaling in ovine uterine endometria from Days 10 to
16 of the estrous cycle and Days 10 to 20 of pregnancy as well as in conceptuses from
Days 13 to 18 of pregnancy were determined. All of these genes were expressed in
ovine uterine endometrium and conceptuses. Among these genes, expression of NOS1,
IGF2, RHEB and EIF4EBP1 changed dynamically due to day of the estrous cycle and
early pregnancy. Progesterone stimulated NOS1 and GCH1 expression while IFNT
inhibited NOS1 expression in uterine endometria, and P4 and IFNT stimulated
expression of RHEB and EIF4EBP1 in uterine endometria.
Collectively, these results indicate that: 1) the availability of select nutrients in
the ovine uterine lumen increases to support the rapid growth and elongation of the
conceptus during the peri-implantation stage of pregnancy; 2) P4 and/or IFNT
stimulate(s) glucose and amino acid transporters to facilitate their transport from
maternal tissues and/or blood into the uterine lumen during early pregnancy; 3) the
FRAP1 cell signaling pathway mediates interactions between the maternal uterus and
peri-implantation conceptus and both P4 and IFNT affect this pathway by regulating expression of RHEB and EIF4EBP1. Expression of NOS, ODC1 and IGF2 appear to be
linked to FRAP1 signaling in both uteri and peri-implantation conceptuses. | en |
