Changes in the composition of the entire body of the albino rat during the life span

Hatai, Shinkishi

doi:10.1002/aja.1000210103

Cited by 48 publications

(16 citation statements)

References 4 publications

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“…In rats, the proportion of body protein increases from birth to adult life (19). Since the lean body mass or body cell mass (an approximate measure of total body protein) is the major contributor to basal metabolism (4, 29) our finding of an invariant proportion of body protein at sexual maturation would be in accordance with the hypothesized metabolic level which, when reached, acts to signal pubertal onset (17,27).…”

supporting

confidence: 42%

“…Except for the constant proportion of body protein, the changes in food intake a n d somatic measurements observed within groups of rats with increasing age at sexual maturation are those which would be expected in rats as they grow older (19,26). Moreover, these findings are inconsistent with the hypothesized attainment of a constant body weight, level of fatness, and food or caloric intake per unit of body weight which are considered to act as a trigger for the onset of pubertal events (14, 1 5 , 2 7 ) .…”

mentioning

confidence: 51%

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Pubertal Food Intake and Body Length, Weight, and Composition in the Feed-Restricted Female Rat: Comparison with Well Fed Animals

Wilen

Naftolin

1978

Pediatr Res

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Summarymaturation earlier but at an average body weight which is not Individual pubertal age, food intake, and body length, weight, and composition were determined by direct measurements in 28 feed-restricted female rats studied from birth to first estrus, and were compared to well fed controls (39). The average birth (6.87 0.19 g) and weaning (49.39 * 0.72 g) weights of the 1 3 early maturing feed-restricted rats did not differ significantly from those of the 13 late maturers (6.72 2 0.31 g and 49.96 * g, respectively). Mean values for all pubertal measurements are included in Table 1. F i t estrus was simultaneous with vaginal opening in nine (69%) of early and two (15%) of the late maturing feed-restricted rats. At first estrus, the late maturing, feed-restricted animals were heavier, longer (Fig. I), and had attained a greater quantity of total body fat, protein, and water than the early maturers. Furthermore, at first estrus the late maturing feed-restricted rats had acquired a greater proportion of body water than the early maturers; however, both groups had attained the same proportion of body protein (Fig. 2). Although early and late maturing feed-restricted rats were eating the same amounts of food at the time of vaginal opening and at f i t estrus, late maturing rats consumed less food per 100 g body wt than did early maturers. The average birth (6.99 2 0.74 g) and weaning (49.7 2 0.74 g) weights of all 29 well fed rats did not differ from those of the feed-restricted group --(6.76 * 0.17 g and 48.95 0.6 g, respectively). F i t estrus was simultaneous with vaginal opening in 20 (69%) of the well fed and 13 (46%) of the feed-restricted rats. At first estrus average body weights and nose-rump length were the same for well fed and feed-restricted groups. Mean ages at vaginal opening and at first estrus in the feed-restricted animals were, however, greater. Absolute amount and percentage of body water did not, on the average, diier in the two groups; however, the feed-restricted animals attained less fat, were proportionately leaner, acquired a greater quantity and proportion of protein, and consumed less food. SpeculationAs seen within the previously studied well fed control group, differences in food intake and somatic development in individual feed-restricted rats at rust estrus suggest that the attainment of a constant body weight, level of fat, or food intake may not be essential for the onset of puberty. Our findings in rats at first estrus suggest that although dietary manipulation may effect a change in the overall proportion of body fat and protein, within a homogeneous group of rats at first estrus there is a percentage of body protein which remains the same with increasing age at sexual maturation.Previous studies have shown that well nourished female animals (1 0,25,27,28,36,37) and humans (1 3) attain sexual 26 statistically different from that reached b; undernourished maturing individuals. Malnourished girls, however, are taller at menarche than their well fed counterparts (13). Well fed fe...

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supporting

confidence: 42%

mentioning

confidence: 51%

Pubertal Food Intake and Body Length, Weight, and Composition in the Feed-Restricted Female Rat: Comparison with Well Fed Animals

Wilen

Naftolin

1978

Pediatr Res

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“…However, the same study showed that patient's body size cannot be disregarded because there was a highly significant correlation between lithium levels in serum and the product of lithium renal clearance and body weight. In this connection, it is pertinent to note that the proportion of fat in the human body increases with body size and with age (Altman and Dittmer 1974, see Table 281), just as it does in rats (Hatai 1917;Schemmel et al 1969;Vague et al 1974). In genetically obese rats, the lipid content of the carcass can be as much as 16 times the lipid content of non-obese controls (Tulp 1990).…”

Section: Discussionmentioning

confidence: 49%

Influence of body size on lithium levels in rats

et al. 1997

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Lithium chloride was injected into rats by the intraperitoneal or intravenous route. The dose was proportional to body weight, in the conventional manner. Lithium levels in blood serum and organs were determined after 3-24 h. Within a given strain, large rats had higher levels than small rats. The size of the rats, and not their age, was the determining factor. The large rats had more adipose tissue than the small rats. Inasmuch as lithium distributes in body water, the excess fat in large rats reduces its volume of distribution, which may be responsible for raising the lithium levels in aqueous compartments, including serum. Male and female rats of equal body size developed equal lithium levels in serum.

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“…Inasmuch as the aging process in many mammals is accompanied by a decrease in the relative contribution of body water to total body weight (and, conversely, an increase in the relative contribution of fat to total body weight) [Edleman et al, 1952;Fryer, 1962;Hatai, 1917], it follows that doses of ethanol administered on the basis of total body weight (g etha nol/kg body weight) will generally produce higher peak blood concentra tions of ethanol in elderly subjects than in young subjects. This generaliza tion has been found to hold true in studies on people of different ages [Vestal et al, 1977] [York, 1982], but the nature of those changes has yet to be clearly delineated.…”

Section: Introductionmentioning

confidence: 43%

Body Water Content, Ethanol Pharmacokinetics, and the Responsiveness to Ethanol in Young and Old Rats

York¹

1982

Dev Pharmacol Ther

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Total body water was determined by desiccation of samples of 6 young (5-7 months) and 6 old (24-26 months) female CD strain rats and was observed to contribute 58.8 ± 1.4 and 45.8 ± 1.7% to the total body mass of the respective groups. The values obtained were used to construct an equation (linear regression: body weight vs. percent body water) with which to estimate the body water content of living subjects (n = 10 each) of the same populations, using body weight as the predictive variable. Doses of ethanol estimated to produce similar drug concentrations in the body water compartments were administered to old and young subjects and were observed to produce similar blood ethanol disappearance curves in both groups of rats. The regional brain concentrations of ethanol were found to be highest in the pons-medulla and lowest in the midbrain. On a region-by-region basis the values obtained for young rats were observed to more closely approximate the concentrations of ethanol in the neck blood than were the values obtained from the analysis of brain tissue from old rats. Old and young subjects dosed on the basis of predicted equivalent dilution of ethanol in body water did not differ noticeably in their response to ethanol hypothermia.

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Changes in the composition of the entire body of the albino rat during the life span

Cited by 48 publications

References 4 publications

Pubertal Food Intake and Body Length, Weight, and Composition in the Feed-Restricted Female Rat: Comparison with Well Fed Animals

Pubertal Food Intake and Body Length, Weight, and Composition in the Feed-Restricted Female Rat: Comparison with Well Fed Animals

Influence of body size on lithium levels in rats

Body Water Content, Ethanol Pharmacokinetics, and the Responsiveness to Ethanol in Young and Old Rats

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