The effect of acute dietary restriction on muscle fibre number in weanling rats

Abstract

1. Milk Sprague-Dawley rats were allocated at 100 g into either an adlib.-fed control group or a food-restricted group. The restricted group was fed for 9 d at 25% of ad lib. intake. Controls were killed at a body-weight of 100 g and 29 d of age and the restricted animals were killed at 70 g and 38 d of age.2. The effects of food restriction on muscle weight, fibre number, fibre diameter, DNA, and protein were examined in three skeletal muscles, the soleus, plantaris and extensor digitorurn longus (EDL).3. Acute dietary restriction caused body-and muscle-weight loss and a decrease in both the number and cross-sectional area of muscle fibres in each of the muscles.4. The restriction halted growth-related increases in DNA in all muscles and decreased the protein: DNA value in the plantaris and EDL.5. These results indicate that present theories describing cellular development are not adequate to define growth potential or growth retardation of skeletal muscle.

Fibre Number and Sizes of Mouse Soleus Muscle in Early Postnatal Protein Malnutrition

“…1979] human [Cheek et al. 1970;Hansen-Smith et al, 1979;Montgomery, 1962] and rats [Hegarty and Kim, 1980;Layman et al, 1981]. This is, however, different from the observations of Rowe [1968] who even though he observed decrease in fibre diameter of the white fast muscles in starved mice did not observe any in the slow soleus muscle.…”

“…Hagerty and Kim [ 1980] and Layman et al 11981 ] on the other hand, observed reduction in number of muscle fibres. Parsons et al [1982] have, however, questioned that reduction in number of muscle fibres observed by Ha gerty and Kim [1980] and Layman et al [1981]. They were of the opinion that the smaller number of muscle fibres observed by those authors was not as a result of loss of muscle fibres but because the authors employed the indirect method of fibre number estimation of Thompson et al [1979] which failed to take into account the architecture of the muscles they studied.…”

“…The smaller number of muscle fibres present in the protein-malnourished mice cannot be as a result of all the muscle fibres not being counted as has been sug gested by Parsons et al [1982] to be responsible for the smaller number of muscle fibres observed in starved rats by Hegarty and Kim [1980] and Layman et al [1981] who employed the indirect method of fibre estimation of Thompson et al [1979). Rayne and Crawford [ 1975] stated that the best way to determine the number of muscle fibres is to choose a muscle small enough that cross-section through its midbelly will include all the fibres which can be counted directly.…”

Cellular Development of Skeletal Muscle during Early Periods of Nutritional Restriction and Subsequent Rehabilitation

“…Skeletal muscle growth and cell development of that early food on mice and pigs, respectively, did not Sprague-Dawley rats were examined at 25 and days of alter fiber number. Hegarty and Kim (10) and Layman et al (13) age in controls (c) and three treatment groups. Each of the three found a decrease in fiber number in hamsters and rats after total treatments consisted of a 50% restriction of food intake for 21 and reported a lower number of days through @station (GR), lactation (LR), and an muscle fibers in infants who died from protein-energy malnutripostweanling period (PWR, of age).…”

“…Dietary restrictions that occur shortly after birth reduce body growth &d proliferation of muscle nuciei (16,31), but the effects This study was designed to examine the effects of periods on skeletal muscle fiber number remain equivocal (1, 2, 8, 9, 10, of nutritional restrictions on the cellular growth potential of 13,16,18,24,26). Rowe (24) and strickland (26) reported skeletal muscle.…”