Maternal nutrient restriction in the ewe from early to midgestation programs reduced steroidogenic enzyme expression and tended to reduce progesterone content of corpora lutea, as well as circulating progesterone in nonpregnant aged female offspring

Abstract

Background: Previously we reported decreased circulating progesterone and fertility in one and two year old ewes born to undernourished mothers. This study was designed to investigate if this reduction in progesterone persisted into old age, and if it did, what mechanisms are involved.

Methods: Ewes were fed a nutrient restricted (NR, 50% of NRC recommendations) or control (C, 100% of NRC) diets from day 28 to 78 of gestation, then all were fed to requirements through parturition and weaning. Female offspring (4 per treatment group) were maintained as a group and fed to requirements from weaning until assigned to this study at 6 years of age. Ewes were synchronized for estrus (day 0) and blood samples were collected daily from day 0 to day 11 before necropsy on day 12. Blood serum and luteal tissue were assayed for progesterone concentrations by validated radioimmunoassay.

Results: Circulation progesterone concentrations tended to be lower (P = 0.06) in NR than C offspring from day 0 to 11 of the estrous cycle. While total luteal weight was similar across groups, total progesterone content also tended to be reduced (P = 0.07) in luteal tissue of NR than C offspring. Activity of hepatic progesterone catabolizing enzymes and selected angiogenic factors in luteal tissue were similar between groups. Messenger RNA expression of steroidogenic enzymes StAR and P450scc were reduced (P < 0.05), while protein expression of StAR tended to be reduced (P < 0.07) and P450scc was reduced (P < 0.05) in luteal tissue of NR versus C offspring.

Conclusions: There appears to be no difference in hepatic steroid catabolism that could have led to the decreased serum progesterone. However, these data are consistent with the programming of decreased steroidogenic enzyme expression in CL of NR offspring, leading to reduced synthesis and secretion of progesterone.

Figure 1

Daily progesterone concentrations into the mid-luteal phase of the estrous cycle in estrus synchronized aged offspring of nutrient restricted and control ewes. Control (n=4; -●-) ewes and nutrient restricted (n=4; -▲-) offspring. Differences are noted; *, P < 0.05 and †, P < 0.10.

Figure 2

Total progesterone content of luteal tissue in aged ewe offspring of control and nutrient restricted dams. Control (n=4, open bars) and nutrient restricted (n=4, solid bars) offspring. Differences are noted; †, P < 0.10.

Figure 3

Enzyme activities from livers of aged ewe offspring of control and nutrient restricted dams for hepatic enzymes involved in progesterone metabolism: cytochrome P450 2C (CYP2C), cytochrome P450 3A (CYP3A), aldo-keto reductase 1C (AKR1C) and cytochrome P450 reductase (P450). Control (n=4, open bars) and nutrient restricted (n=4, solid bars) offspring. No treatment differences were detected. The dashed line separates activities to be read on the left versus right y-axes. There were no significant effects of treatment on the activity of any enzyme.

Figure 4

Protein expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF-2), angiopoietin-1 (ANG-1) and angiopoietin-2 (ANG-2) in corpora luteal tissue from aged female offspring of control and nutrient-restricted dams. Control (n=4, open bars) and Nutrient-restricted (n=4, solid bars) offspring.

Figure 5

Message RNA (A) and protein Levels (B) of steroidogenic acute regulator (StAR) enzyme, P450 side chain cleavage (P450scc) enzyme and 3-β Hydroxysteriod dehydrogenase (3β-HSD) in corpora luteal from aged female offspring of control and nutrient-restricted dams. Control (n=4, open bars) and nutrient-restricted (n=4, solid bars) offspring. Differences are noted; *P < 0.05; †P < 0.10.

Figure 6

Message RNA (A) and protein Levels (B) of peroxiredoxin 3 (PRX-3) in corpora luteal from aged female offspring of control and nutrient-restricted dams. Control (n=4, open bars) and nutrient-restricted (n=4, solid bars) offspring. Differences are noted; *P < 0.05.