scholarly journals Growth and development of rats artificially reared on a high or a low plane of nutrition

1983 ◽  
Vol 49 (3) ◽  
pp. 497-506 ◽  
Author(s):  
J. L. Smart ◽  
D. N. Stephens ◽  
H. B. Katz
Keyword(s):  
Whole Body ◽  
Artificial Rearing ◽  
Rat Pups ◽  
Low Protein ◽  
Epididymal Fat ◽  
Milk Substitute ◽  
Eye Opening ◽  
Pelleted Diet ◽  
Gastrocnemius Muscles ◽  
Tibia Length

1. In order to exclude the possibility of differences in maternal care which are known to result from typical methods of undernutrition during the suckling period, rat pups were reared artificially on different planes of nutrition away from their mothers.2. Artificial rearing was accomplished by fitting infant rats with a gastric cannula through which a milk substitute was infused intermittently. Rats were fed thus from 4 to 21 d on a high (ARHI) or a low (ARLO; 44% of ARHI level) plane of nutrition. Underfeeding of the ARLO group was continued till 25 d, after which all rats were given a good-quality pelleted diet ad lib.3. Compared with mother-reared (MR) litter-mates, ARHI rats showed advanced eye-opening and, at 21 and 25 d, they resisted restraint more strongly.4. Growth in body-weight of ARHI and MR rats was similar but, when autopsied at 32 weeks, the ARHI rats were shorter (nose–rump length) and had lighter gastrocnemius muscles, adrenals and brains, but heavier epididymal-fat pads.5. ARLO rats had deficits at 32 weeks compared with ARHI rats in whole body, kidney and epididymal-fat-pad weights, and in tibia length.6. In a second experiment, ARHI and MR rats were killed at 21 d. All the differences found at 32 weeks were already present at 21 d. In addition, the ARHI pups had enlarged livers and intestines but shorter tibias.7. The milk substitute, which is one commonly used in such studies, has a low protein and high carbohydrate content compared with rats' milk. This difference probably caused the abnormal organ growth of ARHI rats.

scholarly journals Effects of early-life undernutrition in artificially reared rats: subsequent body and organ growth

1987 ◽  
Vol 58 (2) ◽  
pp. 245-255 ◽  
Author(s):  
J. L. Smart ◽  
R. F. Massey ◽  
S. C. Nash ◽  
J. Tonkiss
Keyword(s):  
Early Life ◽  
Growth Curves ◽  
Solid Food ◽  
Whole Body ◽  
Artificial Rearing ◽  
Organ Growth ◽  
Rat Pups ◽  
Milk Substitute ◽  
Eye Opening ◽  
Fat Pads

1. Four groups of rat pups were reared: mother-reared (MR) control (well-fed) and undernourished (MRC and MRU respectively) and artificially reared (AR) control and undernourished (ARC and ARU respectively). Pups for artificial rearing were fitted with a gastric cannula on postnatal day 5 and were fed, by intermittent gastric infusion, expressed rats′ milk (days 5–7), mixtures of rats′ milk and milk-substitute (days 8–16), and milk-substitute only (days 17–20). Solid food was available to MR pups throughout and to AR pups from day 14. Undernutrition, imposed from postnatal days 5 to 25, was effected initially by underfeeding the mother (MRU) or by infusing restricted quantities of milk (ARU). Weaning was at 21 d and undernutrition from day 21 to day 25 was by restricting the supply of solid food. All rats were fedad lib.from 25 d.2. The developmental milestone, eye-opening, was delayed by undernutrition but unaffected by artificial rearing.3. Growth curves in body-weight during the refeeding phase were influenced most by previous undernutrition and to a lesser extent (also negatively) by artificial rearing.4. Fourteen measures of body and organ growth were taken at autopsy at 39 weeks. Twelve measures were affected by nutrition and only four by rearing (weight of whole body, epididymal fat pads, renal fat pads and adrenals).5. AR rats had lighter epididymal and renal fat pads than MR rats perhaps due to the low fat content of the expressed milk they received early in artificial rearing.

scholarly journals Growth and development of rats artificially reared on rats 'milk or rats' milk/milk-substitute combinations

1987 ◽  
Vol 57 (1) ◽  
pp. 3-11 ◽  
Author(s):  
J. Tonkiss ◽  
J. L. Smart ◽  
R. F. Massey
Keyword(s):  
Growth And Development ◽  
Gastrocnemius Muscle ◽  
Heart Weight ◽  
Artificial Rearing ◽  
Organ Growth ◽  
Organ Weights ◽  
Rat Pups ◽  
Body Weights ◽  
Milk Substitute ◽  
Milk Substitutes

1. Rat pups were artificially reared (AR) from post-natal day 5 by intermittent gastric infusion. Mother-reared (MR) siblings served as controls. Fourteen measures of body and organ growth were taken at the end of each experiment.2. In Expt 1, two batches of pups were given rats' milk only, obtained by manual expression from anaesthetized dams.3. The first batch, reared to 12 d, grew less well than the MR group, probably because they received too little milk. However, relative to body-weight, organ weights were as great or greater than those of MR pups, except for heart weight. The second batch, given more milk and reared to 20 d, showed no deficits in organ or body-weights, but excesses in kidney, gastrocnemius muscle, stomach and caecum weights. There were no losses from ‘bloat’, a condition of gastrointestinal distention often encountered in artificial rearing with milk substitutes.4. Obtaining rats' milk is extremely labour-intensive and in Expt 2, more economical regimens were devised in which pups were started off on expressed rats' milk and then changed to a milk substitute resembling rats' milk in composition, either abruptly at 12 d or gradually between 8 and 17 d.5. Both regimens were successful, in that there were no losses from bloat and most measures of growth were at least as great as in the MR group. Only heart weight was lower in both AR groups and adrenal weight in the abruptly changed AR group. The weights of the stomach and caecum and the length of the small intestine were all high in both AR groups.6. It is concluded that giving rat pups expressed rats' milk for the first few days of artificial rearing largely avoids the problem of bloat and results in satisfactory growth.

Artificial rearing of rat pups using rat milk

1990 ◽  
Vol 23 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Elizabeth Moore ◽  
Colleen Stamper ◽  
Jaime Diaz ◽  
Elise Murowchick
Keyword(s):  
Artificial Rearing ◽  
Rat Pups

Malonyl-CoA content and fatty acid oxidation in rat muscle and liver in vivo

2000 ◽  
Vol 279 (2) ◽  
pp. E259-E265 ◽  
Author(s):  
David Chien ◽  
David Dean ◽  
Asish K. Saha ◽  
J. P. Flatt ◽  
Neil B. Ruderman
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Fatty Acyl ◽  
Whole Body ◽  
Acid Oxidation ◽  
Malonyl Coa ◽  
Plasma Ffa ◽  
Gastrocnemius Muscles ◽  
Time Point

Malonyl-CoA acutely regulates fatty acid oxidation in liver in vivo by inhibiting carnitine palmitoyltransferase. Thus rapid increases in the concentration of malonyl-CoA, accompanied by decreases in long-chain fatty acyl carnitine (LCFA-carnitine) and fatty acid oxidation have been observed in liver of fasted-refed rats. It is less clear that it plays a similar role in skeletal muscle. To examine this question, whole body respiratory quotients (RQ) and the concentrations of malonyl-CoA and LCFA-carnitine in muscle were determined in 48-h-starved rats before and at various times after refeeding. RQ values were 0.82 at baseline and increased to 0.93, 1.0, 1.05, and 1.09 after 1, 3, 12, and 18 h of refeeding, respectively, suggesting inhibition of fat oxidation in all tissues. The increases in RQ at each time point correlated closely ( r = 0.98) with increases (50–250%) in the concentration of malonyl-CoA in soleus and gastrocnemius muscles and decreases in plasma FFA and muscle LCFA-carnitine levels. Similar changes in malonyl-CoA and LCFA-carnitine were observed in liver. The increases in malonyl-CoA in muscle during refeeding were not associated with increases in the assayable activity of acetyl-CoA carboxylase (ACC) or decreases in the activity of malonyl-CoA decarboxylase (MCD). The results suggest that, during refeeding after a fast, decreases in fatty acid oxidation occur rapidly in muscle and are attributable both to decreases in plasma FFA and increases in the concentration of malonyl-CoA. They also suggest that the increase in malonyl-CoA in this situation is not due to changes in the assayable activity of either ACC or MCD or an increase in the cytosolic concentration of citrate.

scholarly journals Artificial Rearing of Rat Pups Reveals the Beneficial Effects of Mother Care on Neonatal Inflammation and Adult Sensitivity to Pain

2009 ◽  
Vol 66 (3) ◽  
pp. 272-277 ◽  
Author(s):  
Cynthia B de Medeiros ◽  
Alison S Fleming ◽  
Celeste C Johnston ◽  
Claire-Dominique Walker
Keyword(s):  
Artificial Rearing ◽  
Beneficial Effects ◽  
Rat Pups ◽  
Sensitivity To Pain

Different modes of activating phosphofructokinase, a key regulatory enzyme of glycolysis, in working vertebrate muscle

2002 ◽  
Vol 30 (2) ◽  
pp. 264-270 ◽  
Author(s):  
G. Wegener ◽  
U. Krause
Keyword(s):  
Metabolic Regulation ◽  
Rana Temporaria ◽  
Muscle Metabolism ◽  
Fold Increase ◽  
Whole Body ◽  
Glycolytic Flux ◽  
Open Questions ◽  
Vertebrate Muscle ◽  
Repeated Exercise ◽  
Gastrocnemius Muscles

Glycolytic flux in white muscle can be increased several-hundredfold by exercise. Phosphofructokinase (PFK; EC 2.7.1.11) is a key regulatory enzyme of glycolysis, but how its activity in muscle is controlled is not fully understood. In order not to neglect integrative aspects of metabolic regulation, we have studied in frogs (Rana temporaria) a physiological form of muscle work (swimming) that can be triggered like a reflex. We analysed swimming to fatigue in well rested frogs, recovery from exercise, and repeated exercise after 2 h of recovery. At various times, gastrocnemius muscles were tested for glycolytic intermediates and effectors of PFK. All metabolites responded similarly to the two periods of exercise, with the notable exception of fructose 2,6-bisphosphate (F2,6P2), which we proved to be a most potent activator of frog muscle PFK. The first bout of exercise triggered a more than 10-fold increase in F2,6P2; PFK activity and the content of F2,6P2 in muscle were well correlated. F2,6P2 decreased to pre-exercise levels in fatigued frogs and it virtually disappeared during recovery. Varying by a factor of 70, F2,6P2 was the most dynamic of all metabolites in muscle. Even more surprisingly, F2,6P2 did not respond at all to a second bout of exercise. Other activators of PFK, such as Pi, AMP and ADP, are increased as a consequence of increased ATP turnover in contracting muscle cells. This does not apply to F2,6P2, which is likely to respond to extracellular signals and could be involved in mechanisms by which muscle metabolism is integrated into the metabolism of the whole body. Whether this phenomenon exists in vertebrates other than the frog, and maybe even in humans, and how the content of F2,6P2 in muscle is controlled are intriguing open questions.

scholarly journals Effect of Low-Frequency Vibration on Muscle Response under Different Neurointact Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Chaofei Zhang ◽  
Wenjun Wang ◽  
Dennis Anderson ◽  
Sishu Guan ◽  
Guofa Li ◽  
...  
Keyword(s):  
Stretch Reflex ◽  
Muscle Force ◽  
Low Frequency ◽  
Quantitative Relationship ◽  
Length Change ◽  
Whole Body ◽  
Sprague Dawley ◽  
Nonlinear Hysteresis ◽  
Low Frequency Vibration ◽  
Gastrocnemius Muscles

Stretch reflex is an important factor that influences the biomechanical response of the human body under whole-body vibration. However, there is a lack of quantitative evaluation at lower frequencies. Thus, the aim of this study was to investigate the effects of vibration on the stretch reflex and, in particular, to explore the quantitative relationship between dynamic muscle responses and low-frequency vibrations. The gastrocnemius muscle of 45 Sprague-Dawley rats was dissected. Sinusoidal vibrations of five discrete frequencies (2~16 Hz) with peak-to-peak amplitudes of 1 mm were applied to the gastrocnemius muscles with 2 mm or 3 mm prelengthening. Variables including dynamic muscle force, vibration acceleration, and displacement were recorded in two conditions, with and without the stretch reflex. Results showed that the dynamic muscle forces decreased by 20% on average for the 2 mm prelengthening group after the stretch reflex was blocked and by 24% for the 3 mm prelengthening group. Statistical analysis indicated that the amplitude of dynamic muscle force in the “with stretch reflex” condition was significantly larger than that in the “without stretch reflex” condition (p<0.001). The tension-length curve was found to be a nonlinear hysteresis loop that changed with frequency. The phase difference between the dynamic muscle force and the length change was affected significantly by vibration frequency (p<0.01), and the minimum frequency was 4–8 Hz. Experimental results of this study could benefit musculoskeletal model by providing a theoretical support to build a stretch reflex model for low-frequency vibration.

Rapid changes in metabolic cold defense and GDP binding to brown adipose tissue mitochondria of rat pups

1993 ◽  
Vol 264 (5) ◽  
pp. R1017-R1023 ◽  
Author(s):  
G. Kortner ◽  
K. Schildhauer ◽  
O. Petrova ◽  
I. Schmidt
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Time Course ◽  
Developmental Changes ◽  
Whole Body ◽  
Rat Pups ◽  
Brown Adipose ◽  
Rapid Changes ◽  
Whole Body Metabolism

To determine developmental changes of brown adipose tissue (BAT) thermogenic activity at defined circadian and thermal states, we evaluated the time course of cold-induced increases of in vitro guanosine 5'-diphosphate (GDP) binding in parallel with whole body metabolism (oxygen consumption, VO2) and core temperature (Tc) in 1- to 11-day-old rat pups. During the maximum phase of the juvenile diurnal cycle, Tc of littermates was recorded continuously and VO2 alternately until 2 min before animals were killed for removal of interscapular BAT. GDP binding after 1.5 h at thermoneutrality and its increase during physiologically comparable cold loads were significantly lower in 1-day-old pups than in 5- and 11-day-old pups. Cold defense was activated more rapidly in the older pups, but GDP binding in even the 1-day-old pups was significantly increased during the second 10-min period of cold exposure. We conclude that rapid changes in thermogenic activity, in connection with the known developmental changes in the dependence of the suckling rat's metabolic cold defense on maternal and sibling contact and circadian phase, will distort longitudinal studies of any fast-changing BAT parameter when the conditions immediately before tissue removal are not thoroughly controlled.

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