Neonatal phosphate nutrition alters in vivo and in vitro satellite cell activity in pigs

Abstract

Satellite cell activity is necessary for postnatal skeletal muscle growth. Severe phosphate (PO(4)) deficiency can alter satellite cell activity, however the role of neonatal PO(4) nutrition on satellite cell biology remains obscure. Twenty-one piglets (1 day of age, 1.8 ± 0.2 kg BW) were pair-fed liquid diets that were either PO(4) adequate (0.9% total P), supra-adequate (1.2% total P) in PO(4) requirement or deficient (0.7% total P) in PO(4) content for 12 days. Body weight was recorded daily and blood samples collected every 6 days. At day 12, pigs were orally dosed with BrdU and 12 h later, satellite cells were isolated. Satellite cells were also cultured in vitro for 7 days to determine if PO(4) nutrition alters their ability to proceed through their myogenic lineage. Dietary PO(4) deficiency resulted in reduced (P < 0.05) sera PO(4) and parathyroid hormone (PTH) concentrations, while supra-adequate dietary PO(4) improved (P < 0.05) feed conversion efficiency as compared to the PO(4) adequate group. In vivo satellite cell proliferation was reduced (P < 0.05) among the PO(4) deficient pigs, and these cells had altered in vitro expression of markers of myogenic progression. Further work to better understand early nutritional programming of satellite cells and the potential benefits of emphasizing early PO(4) nutrition for future lean growth potential is warranted.

Keywords: neonatal; phosphate; pig; satellite cell.

Figure 1

Effect of dietary PO₄ on the gene expression of (A) CASR, and (B) calcitonin, in the thyroid of neonatal pigs. Values presented are least square means and standard error of values normalized to cDNA concentrations (n = 7). ^a,b Values not sharing a common superscript are different (P < 0.05).

Figure 2

Effect of dietary PO₄ on in vitro satellite cell proliferation. ^a,b Values not sharing a common superscript are different (P < 0.05). Values presented are least square means and standard error (n = 7).

Figure 3

Effect of dietary PO₄ on the gene expression (top panels) and in vitro protein (bottom panels) of myogenic regulatory factors: (A, D), Pax7, (B, E) MyoD, and (C, F) myogenin in satellite cells isolated from neonatal pigs. Values presented are least square means and standard error of values; either percentage of stained nuclei or normalized to cDNA concentrations (n = 7). ^a,b Values within a timepoint not sharing a common superscript are different (P < 0.05).