PSI-25 Effects of restricted maternal nutrition and realimentation during gestation on the fetal progenitor cell population in semitendinosus muscle of sheep

Abstract

Abstract Satellite cells are muscle stem cells that contribute to postnatal growth. The satellite cell population is established during fetal muscle development, through the retention of Pax7-expressing myogenic progenitor cells. We hypothesized that realimentation during late gestation would ameliorate the negative effect of poor maternal nutrition during mid-gestation on the fetal myogenic progenitor cell population. To test this hypothesis, 47 ewes pregnant with singletons were fed a control diet of 100% of National Research Council (NRC) requirements (CON) starting at day 25 of gestation. At day 50 of gestation, six ewes were euthanized and the remainder were randomly assigned to one of two diets: CON or 60% of CON (RES). On day 90 of gestation, a subset of ewes were euthanized (n = 7 per treatment) and fetal semitendinosus samples were collected. The remaining ewes were maintained on the current diet (CON-CON, RES-RES) or switched to the alternative diet (CON-RES, RES-CON). On day 130 of gestation, all ewes were euthanized for fetal sample collection (n = 6–7 per treatment). Fetal semitendinosus was cryosectioned and immunostained for detection of Pax7(+) cells followed by image analysis. Data were analyzed using the MIXED procedure in SAS. Semitendinosus from RES lambs had a greater number of Pax7(+) cells but similar total cell numbers to CON offspring, resulting in a greater percentage of Pax7(+) cells at d90 of gestation (CON: 13.22 ± 0.74%; RES: 16.01 ± 0.74%, P = 0.01). At day 130, there was no difference in the percentage of Pax7(+) cells between dietary treatment groups (CON-CON: 7.88 ± 0.80%; CON-RES: 6.34 ± 0.74%; RES-RES: 7.82 ± 0.74%; RES-CON: 6.87 ± 0.74%; P > 0.17). The percentage of Pax7(+) cells decreased from day 90 to day 130, regardless of dietary treatment (P < 0.0001). In summary, restricted maternal nutrition may delay progenitor cell differentiation at mid-gestation.