Food and light as separate entrainment signals for rat liver enzymes

Hopkins, Harold A.; Bonney, Robert J.; Walker, P. Roy; Yager, James D.; Potter, Van R.

doi:10.1016/0065-2571(73)90015-0

Cited by 85 publications

(20 citation statements)

References 22 publications

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“…Under all experimental conditions, circadian variations in PK and G6PDH activity were similar to those observed by others (16,36,46). Our results con cerning circadian variations of ME disagree with observations reported by Szepesi and Freedland (46), but such disagreements may be explained by the fact that in their experiment, diurnal variations of enzyme activity were studied during the first 48 h after the change in diets (from high glucose to high fructose or high protein diet) and animals were not adapted to the dietary regime.…”

Section: Discussionsupporting

confidence: 64%

Schedule of Protein Ingestion and Circadian Rhythm of Certain Hepatic Enzyme Activities Involved in Glucose Metabolism in the Rat

Péret

Chanez

Pascal³

1976

Ann Nutr Metab

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The circadian rhythms of liver glycogen, plasma glucose, corticosterone and insulin, and hepatic activity of PK, G6PDH, ME, Ac.CoA carbox. PEP-CK and GPT were studied in adult rats. Animals either received a mixed diet ad libitum (8 % protein) or a protein meal (1.1 g protein) given at 05:00 or 17:00 h, with free access to a protein-free diet (separately fed). When the protein meal was ingested during the lighted period (17:00) the 24-hour average level of liver PEP-CK was greater than in rats consuming protein during darkness (05:00). In the latter case, modification of the circadian rhythm of liver glycogen and of circadian rhythm of liver PK, G6PDH, ME and Ac.CoA carbox. activity (increase of 24 h average level, extension of period of high activity, sudden increase after ingestion of protein meal) were observed. Conversely, the circadian rhythm of plasma insulin and corticosterone and of liver PEP-CK and GPT activity were only slightly affected by the mode of feeding.

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Section: Discussionsupporting

confidence: 64%

Schedule of Protein Ingestion and Circadian Rhythm of Certain Hepatic Enzyme Activities Involved in Glucose Metabolism in the Rat

Péret

Chanez

Pascal³

1976

Ann Nutr Metab

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“…During regeneration (about 24 hr postoperatively), hepatic plasma membranes become partially resistant to binding glucagon; this change is specific because it is not detected in laparotomized controls and insulin binding is not significantly altered. It remains to be proven whether any one or more of these specific endocrine changes are causally related to the initiation of hepatic proliferation.…”

mentioning

confidence: 99%

“…Measurements were performed during the period that precedes maximal DNA replication rates (0-24 hr) because regulatory changes initiating growth would be expected to occur during this time (1 (23,24). Partial hepatectomies were performed according to routine procedures (25), and to demonstrate specific "dose-response" relationships (26), we ablated different amounts of liver tissue.…”

mentioning

confidence: 99%

Specific endocrine and hormonal receptor changes associated with liver regeneration in adult rats.

Leffert¹,

Alexander²,

Faloona³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

113

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Partial removal of the adult rat liver-a procedure that stimulates liver regeneration-causes arterial levels of insulin and thyroxin to fall and glucagon levels to rise. These changes are correlated with the quantity of liver tissue excised and not solely with nonspecific operative manipulations or with blood glucose levels. During regeneration (about 24 hr postoperatively), hepatic plasma membranes become partially resistant to binding glucagon; this change is specific because it is not detected in laparotomized controls and insulin binding is not significantly altered. It remains to be proven whether any one or more of these specific endocrine changes are causally related to the initiation of hepatic proliferation.The phenomenon of liver regeneration in adult rats has been investigated for many years in attempts to understand processes that control mammalian cell proliferation. After partial removal of the liver (partial hepatectomy), the remaining tissue undergoes metabolic changes which culminate in the initiation of hepatocyte DNA synthesis and mitosis about 14 and 24 hr later, respectively, and which continue until the initial cellular mass is restored (1).It has been proposed that hepatocyte proliferation is controlled by blood-borne factors, the levels of which appear to be regulated by the available liver mass (2). Indirect in vvo evidence suggests that hormones may be involved (3-8). Recently, it has been reported that in adult rats, peripheral venous perfusions of glucagon and thyroxin-but not insulinstimulate partial hepatocellular growth similar to the hyperplasia induced by partial hepatectomy (9). However, a growth regulatory role for pancreatic hormones is controversial (10-13); moreover, neither glucagon nor thyroxin appear to be specific hepatotrophic mitogens (14).A conceptual attempt to unify these apparently unrelated findings was discussed elsewhere (15, 16) and was based upon in vitro growth control studies using chemically defined medium and quiescent monolayer cultures (17) of differentiated fetal rat hepatocytes (18-21). Direct evidence from these studies suggested that many serum (22) and conditioning factors (17) contributed to the growth response, including insulin and thyroxin, which partially stimulated the initiation of DNA synthesis, and glucagon, which partially inhibited this process.These findings suggested that the in vivo induction of liver regeneration by partial hepatectomy might be accompanied by specific alterations in plasma levels of these hormones as well as in the liver's capacity for hormonal responsiveness.Accordingly, we began approaching these problems by measuring plasma levels of insulin, glucagon, and thyroxin in partially hepatectomized rats and by measuring the capacity of plasma membranes derived from regenerating liver to bind peptide hormones. Measurements were performed during the period that precedes maximal DNA replication rates (0-24 hr) because regulatory changes initiating growth would be expected to occur during this time (1). MATERIALS AND...

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“…During the suckling period the rats are independent of the artificial light-dark cycle, which is otherwise the strongest influencing factor, at least in the case of rodents [Bhattacharya, 1981[Bhattacharya, , 1983, With the opening of the eyes during the weaning period the adaptation to the artificial light-dark cycle begins, which probably alters the pattern of enzymatic distribu tion. Hopkins et al [1973] have mentioned that the induc tion of enzymes involves an interaction between dietary factors and hormonal factors related to the light-dark period. The major structural change which occurred in the liver of the two groups is the production of tetraploid cells, which reach a 1:1 proportion in 50-g rats [Naora.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Topochemistry of Rat Liver Enzymes during Postnatal Development in Relation to Activity-Rest Cycle

Bhattacharya¹,

Araki²,

Yamada³

1987

Cells Tissues Organs

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A quantitative histochemical method (Trident) has been adapted to measure the activities of 4 enzymes, succinate dehydrogenase (SD), isocitrate dehydrogenase (ICD), glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6-PGD), within the liver acini of the rat during the postnatal developmental period. Quantitative changes of these enzymes in livers of rats of 25 g and 50 g body weight were studied, with particular emphasis on the activity-rest cycle. The results indicate a time-dependent heterogeneous distribution of enzymes along the acinar zones and the pattern of localization is age-dependent. When the mean enzyme activity from each group in relation to the time of the day are compared, a mirror image of each other could be seen. In general, a high enzyme activity has been observed during the resting phase in 25-g rats and low in 50-g rats. During the developmental period, the mean ICD activity is diminished, whereas G6PD and 6-PGD are augmented, and SD activity remains unchanged.

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Food and light as separate entrainment signals for rat liver enzymes

Cited by 85 publications

References 22 publications

Schedule of Protein Ingestion and Circadian Rhythm of Certain Hepatic Enzyme Activities Involved in Glucose Metabolism in the Rat

Schedule of Protein Ingestion and Circadian Rhythm of Certain Hepatic Enzyme Activities Involved in Glucose Metabolism in the Rat

Specific endocrine and hormonal receptor changes associated with liver regeneration in adult rats.

Quantitative Topochemistry of Rat Liver Enzymes during Postnatal Development in Relation to Activity-Rest Cycle

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