EFFECTS OF RESTRICTED FOOD INTAKE AND GROWTH HORMONE ON RAT LIVER PROTEINS AND NUCLEIC ACIDS¹

Regulation of the rate of synthesis of messenger ribonucleic acid by growth hormone

“…That growth hormone exerts a stimulatory effect on the synthesis of liver RNA has been known for some time. Hypophysectomy results in a fall in the RNA content of rat liver, and the administration of growth hormone reverses this fall (Reid, O'Neal, Stevens & Burnop, 1956;Di Stefano & Diermeier, 1959). Talwar, Panda, Sarin & Tolani (1962) reported a marked stimulation of incorporation of 32p into fractions of rat-liver RNA after injection of growth hormone.…”

Ploidy and biochemical characteristics of liver cell nuclei in rats fed different amounts of dietary protein

“…It is clear from other studies that either caloric restriction or pituitary ablation can result in reduced polyploidy (Bass and Dunn 1957;Di Stefano and Diermeier 1959;Nadal and Zajdela 1965b). Furthermore, pair-feeding data suggest that the effects of pituitary ablation are not mediated through reduced food intake (Bass and Dunn 1957;Di Stefano and Diermeier 1959) However, reduced caloric intake may have played a minor role in the mediation of these effects since the intakes of the two diets were shown to be very similar when computed per unit of body weight (Table ix). Third, the possibility should be considered that the eighteen hour starvation period prior to autopsy, as was routinely used in these ex periments, could have altered or attenuated the development of polyploidy.…”

“…Since they did not observe such reductions in the pair fed group, they con cluded that the effect of pituitary hormones was not secondary to reduced food intake. On the other hand, when Di Stefano and Diermeier (1959) included a hypophysectomized group given growth hormone, their data suggested that both growth hormone and food intake were involved in the ploidy shift from diploid to tetraploid.…”

“…In a study of total nuclear RNA content in growing rats, Di Stefano and Diermeier (1959) reported that a seven day period of restricted food intake was accompanied by a reduction in nuclear RNA. Utilizing a cytophotometric assay, the nuclear RNA contents (measured by difference before and after ribonuclease digestion) were expressed in relative extinction units.…”

Ploidy and biochemical characteristics of liver cell nuclei in rats fed different amounts of dietary protein

“…The studies examining the role of food intake and pitui tary hormones suggest that both of these factors may inde pendently regulate hepatic nuclear ploidy. Bass and Dunn (1957) Stefano and Diermeier (1959) included a hypophysectomized group given growth hormone, their data suggested that both growth hormone and food intake were involved in the ploidy shift from diploid to tetraploid.…”