Growth and metabolism of fetal and maternal muscles of adolescent sheep on adequate or high feed intakes: possible role of protein kinase C-α in fetal muscle growth

Abstract

From days 4-104 of pregnancy, adolescent sheep, weighing 43.7 (SE 047)kg were offered a complete diet at two different intakes (approximately 5 or 15kglweek) designed to meet slightly, or well above, maternal maintenance requirements. The fetal and maternal muscles were taken on day 104 of pregnancy and analysed for total DNA, RNA and protein. Ewes offered a high intake to promote rapid maternal weight gain, weighed more (76.5 (SE 4.5) v. 50.0 (SE 1.7)kg) and had muscles with a greater fresh weight, whilst their fetuses had smaller muscles, than those fed at a lower intake. Plantaris muscle of the ewes fed at the high intake contained more RNA and protein; again the opposite situation was found in the fetal muscle. On the higher maternal intakes, the DNA, RNA and protein contents of the fetal plantaris muscle were less than in fetuses of ewes fed at the lower intake. To investigate the possible mechanisms involved in this decrease in fetal muscle mass, cytosolic and membrane-associated muscle proteins were subjected to Western immunoblotting with antibodies to nine isoforms of protein kinase C (PKC), a family of enzymes known to play an important role in cell growth. Five PKC isoforms (a, E, 0, and 5) were identified in fetal muscle. One of these, PKC-a, was located predominantly in the cytosolic compartment in the smaller fetuses of the ewes fed at a high plane of nutrition, but was present to a greater extent in the membranes of the more rapidly growing fetuses of the ewes fed at the lower intake. This was the only isoform to demonstrate nutritionally related changes in its subcellular compartmentation suggesting that it may mediate some aspects of the change in fetal growth rate.

Variable maternal nutrition and growth hormone treatment in the second quarter of pregnancy in pigs alter semitendinosus muscle in adolescent progeny

“…In addition, these studies were conducted in a commercial population that has very low genetic heterogeneity, so heavier gilts are probably also slightly more mature than lighter gilts and will have slightly less nutrient demand for maternal growth during pregnancy. Nutritional manipulations that increase maternal growth in adolescent sheep compromise growth of their placenta and fetus (Wallace et al 1996), and fetal muscle growth is reduced in conjunction with increased maternal muscle and fat deposition in the adolescent sheep (Palmer et al 1998). The association between the concentrations of IGF-II in maternal blood at the end of the first third of pregnancy and the density of muscle fibres in adolescent progeny suggests a novel potential role for maternal IGF-II during pregnancy in an intra-uterine programming mechanism.…”

Translocation of protein kinase C isoforms in rat muscle in response to fasting and refeeding

“…Of the nine PKC isoforms examined, five (a, , z, v and ) were detected in plantaris muscle of the weanling rat. The same isoforms were found in muscles of the fetal sheep (Palmer et al 1998), whilst a study by Thompson et al (1997), using the same antibodies, additionally found PKC isoforms d and i. Surprisingly, that study failed to find PKCv, an isoform originally identified from muscle (Osada et al 1992).…”

“…Cytosolic and membrane-bound protein fractions of plantaris and soleus muscles were extracted and Western immunoblotting was performed as described previously (Palmer et al 1998). Protein content of the extracts was measured by the method of Bradford (1976).…”

A review of fundamental principles for animal models of DOHaD research: an Australian perspective

“…Placenta, [288][289][290] cardiovascular, 291 liver, 292 pancreas, 293,294 Overnutrition adolescent mother Placenta, [295][296][297] skeletal muscle 298 Uteroplacental embolization…”