scholarly journals The hormonal regulation of enzymes in prenatal and postnatal rat liver. Effects of adenosine 3′,5′-(cyclic)-monophosphate

1969 ◽  
Vol 115 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Olga Greengard
Keyword(s):  
Growth Hormone ◽  
Hormonal Regulation ◽  
Time Course ◽  
Tyrosine Aminotransferase ◽  
Cyclic Monophosphate ◽  
Sequential Development ◽  
Foetal Liver ◽  
Old Rats ◽  
Postnatal Rats ◽  
Do So

1. The administration of glucagon, cAMP [adenosine 3′,5′-(cyclic)-monophosphate], BcAMP [6-N-2′-O-dibutyryladenosine 3′,5′-(cyclic)-monophosphate] or adrenaline to foetal rats during the last 2 days of gestation evoked the appearance of tyrosine aminotransferase and enhanced the accumulation of glucose 6-phosphatase in the liver. In foetuses 1–2 days younger only BcAMP was effective. After birth liver glucose 6-phosphatase no longer responds to glucagon or BcAMP. Tyrosine aminotransferase is still inducible by these agents in 2-day-old rats, but not in 50-day-old rats. After adrenalectomy of adults glucagon or BcAMP can enhance the induction of the enzyme by hydrocortisone. The results indicate that the ability to synthesize tyrosine aminotransferase and glucose 6-phosphatase when exposed to cAMP develops sooner than the ability to respond to glucagon with an increase in the concentration of cAMP; the responsiveness of enzymes to different hormones changes with age. A scheme illustrating the sequential development of competence in regulating the level of an enzyme is presented. 2. Actinomycin inhibited the effects of glucagon and BcAMP on liver tyrosine aminotransferase and glucose 6-phosphatase in foetal rats. Growth hormone, insulin and hydrocortisone did not enhance the formation of these enzymes. 3. The time-course of accumulation of glucose 6-phosphatase in the kidney is different from that in the liver. Hormones that increase the accumulation in foetal liver do not do so in the kidney of the same foetus or in the livers of postnatal rats.

scholarly journals Influence of glucagon, 6-N,2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate and triamcinolone on the arginine synthetase system in perinatal rat liver

1972 ◽  
Vol 126 (1) ◽  
pp. 89-98 ◽  
Author(s):  
A L. Schwartz
Keyword(s):  
Cyclic Amp ◽  
Rat Liver ◽  
Cyclic Nucleotide ◽  
Time Course ◽  
Fold Increase ◽  
Dibutyryl Cyclic Amp ◽  
System Activity ◽  
Cyclic Monophosphate ◽  
Foetal Rat ◽  
Postnatal Rats

1. The administration of triamcinolone (19–190μg/animal) to postnatal rats increased the arginine synthetase system activity 1.2–2.5-fold above control values 24h after exposure to the hormone. Cortisol (hydrocortisone), however, increased the arginine synthetase system activity only when larger (190μg/animal) or repeated daily doses were given. Glucagon (100μg/animal) stimulated arginine synthetase system activity only after the second postnatal day. None of these agents increased the activity in 19.5–21.5-day foetuses after intrauterine administration. 2. The viability of foetal rat liver explants maintained in organ culture for up to 54h was validated both by ultramicroscopic examination and by incorporation of radioactive leucine and orotic acid. 3. In organ cultures of foetal rat liver explants (18.5 days to term), triamcinolone (20μg/ml of medium) evoked a 2.8–4.3-fold increase after 24h of incubation. This increase was completely inhibited by actinomycin D (25μg/ml) or cycloheximide (10μg/ml). Cortisol (5–50μg/ml) or glucagon (0.067–67μg/ml) also increased the arginine synthetase system activity above the respective control values, but there was no increase in activity with insulin (0.05–0.25i.u./ml). 4. Maximum concentrations of glucagon (67μg/ml), dibutyryl cyclic AMP (6-N,2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate) (0.1mm) and triamcinolone (20μg/ml) incubated for 24h with foetal rat liver explants each produced between a two-and three-fold increase in the activity of the arginine synthetase system. Combinations of maximum amounts of glucagon and the cyclic nucleotide did not produce a greater effect than either agent alone. However, the combination of dibutyryl cyclic AMP with triamcinolone appeared to produce somewhat less than additive effects. 5. The effects of the cyclic nucleotide and triamcinolone were evident after 12h of incubation and increased steadily throughout the 24h of observation. This time-course of increased enzyme activity is very much slower than that reported for the induction of other enzymes in explant cultures of foetal rat liver.

Do “So-Called” Normal Growth Hormone Concentrations (2-5 µg/l) Indicate Cure in Acromegaly?

1995 ◽  
Vol 27 (04) ◽  
pp. 185-188 ◽  
Author(s):  
Naomi Levitt ◽  
B. Ratanjee ◽  
M. Abrahamson
Keyword(s):  
Growth Hormone ◽  
Normal Growth ◽  
Do So

Growth hormone, cortisol, or both are involved in defense against, but are not critical to recovery from, hypoglycemia

1991 ◽  
Vol 260 (3) ◽  
pp. E395-E402 ◽  
Author(s):  
P. J. Boyle ◽  
P. E. Cryer
Keyword(s):  
Growth Hormone ◽  
Plasma Glucose ◽  
Low Doses ◽  
Short Term ◽  
Control Subjects ◽  
Glucose Recovery ◽  
Do So

We tested the hypotheses that growth hormone, cortisol, or both are involved in defense against but are not critical to recovery from prolonged hypoglycemia and that the putative roles of these hormones in defense against prolonged hypoglycemia are permissive rather than direct. To do so we studied control subjects (n = 10) and patients with growth hormone and cortisol deficiencies resulting from hypopituitarism both in the untreated state (n = 7) and with prestudy and basal intrastudy growth hormone and cortisol replacement (n = 6). Postabsorptive plasma glucose, insulin, glucagon, and epinephrine concentrations were no different in the untreated patients and controls. Twelve-hour insulin infusions, in low doses adjusted over the 1st 2 h to produce plasma glucose concentrations of 3.6 mmol/l (65 mg/dl) and then fixed at that dose, resulted in significantly (P less than 0.0001) lower late plasma glucose concentrations in the patients, without and with replacement. The 12-h plasma glucose concentrations were 2.9 +/- 0.1 mmol/l (53 +/- 1 mg/dl) in the control subjects, 2.4 +/- 0.1 mmol/l (43 +/- 2 mg/dl; P less than 0.001 vs. control) in the deficient patients, and 2.5 +/- 0.1 mmol/l (45 +/- 2 mg/dl; P less than 0.01 vs. control) in the replaced patients. Rates of glucose recovery from hypoglycemia after discontinuation of insulin were identical in all three studies. Thus growth hormone, cortisol, or probably both play a demonstrable role in defense against prolonged, in contrast to short-term, hypoglycemia in humans. This does not appear to be the result of permissive actions of the hormones and is therefore best attributed to their increments during hypoglycemia.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Biochemical changes in cultured foetal rat liver explants

1975 ◽  
Vol 150 (2) ◽  
pp. 269-273 ◽  
Author(s):  
P C MacDonnel ◽  
E Ryder ◽  
J A Delvalle ◽  
O Greengard
Keyword(s):  
Soluble Protein ◽  
Cell Damage ◽  
Tyrosine Aminotransferase ◽  
Culture Conditions ◽  
Total Soluble Protein ◽  
Mitochondrial Enzymes ◽  
Stage Of Development ◽  
Foetal Rat ◽  
Total Soluble Protein Content ◽  
Do So

Liver explants from 20-day-old foetuses cultured for 48h in the absence of serum released 70% of their total soluble protein content into the medium. In the presence of serum this loss still amounted to 60%. The concentration of total particulate protein remained unchanged but there was some translocation of mitochondrial enzymes to the cytosol, and enzymes expected to increase during this stage of development failed to do so. The addition of cortisol plus glucagon (to serum-containing media) did not decrease the loss of total soluble protein from the explants but induced considerable tyrosine aminotransferase activity which was not released into the medium. The observations suggest that under the usual culture conditions a minority of the cells retain their functional integrity. The extent of deterioration, not reflected in histologically visible necrosis or cell damage, can be conveniently monitored by the malate dehydrogenase activity released to the medium.

Effects of Growth Hormone Releasing Peptides on Stimulated Growth Hormone Secretion in Old Rats

1994 ◽  
pp. 167-192 ◽  
Author(s):  
Richard F. Walker ◽  
Sei-Won Yang ◽  
Ryuji Masuda ◽  
Cheng-Shih Hu ◽  
Barry B. Bercu
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Old Rats ◽  
Growth Hormone Releasing Peptides

Effect of growth hormone on gastrocnemius muscle of aged rats after immobilization: biochemistry and morphology

1993 ◽  
Vol 75 (4) ◽  
pp. 1529-1535 ◽  
Author(s):  
E. Carmeli ◽  
Z. Hochberg ◽  
E. Livne ◽  
I. Lichtenstein ◽  
C. Kestelboim ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Gastrocnemius Muscle ◽  
Muscle Protein ◽  
Aged Rats ◽  
Muscle Weight ◽  
Hindlimb Muscles ◽  
Capillary Blood Volume ◽  
Rat Growth ◽  
Old Rats ◽  
Limb Immobilization

Immobilization of limbs of aged animals is associated with swift muscular damage and atrophy. We investigated the effect of rat growth hormone (rGH) on immobilized hindlimb muscles of 26-mo-old rats. Administration of rGH significantly reduced muscle weight loss and muscle protein oxidation caused by immobilization. Capillary blood volume, measured by photoplethysmography of the hindlimb, showed a 34% reduction in immobilized animals, which was eliminated by rGH. The activity of creatine phosphokinase in immobilized gastrocnemius muscle was significantly reduced by immobilization. This damage was diminished by rGH administration. Similarly, the increase in acid phosphatase activity in immobilized muscle was reduced after rGH treatment. Morphologically, marked muscle atrophy and fiber disorientation were observed in immobilized limbs. Therapy with rGH prevented some of these changes. These results indicate that administration of rGH may provide a useful means to attenuate the degenerative effects of limb immobilization of aged rats, as evident from physiological, biochemical, and morphological parameters.

DOSE REGIMENS OF HUMAN GROWTH HORMONE: EFFECTS OF CONTINUOUS INFUSION AND OF A GELATIN VEHICLE ON GROWTH IN RATS AND RATE OF ABSORPTION IN RABBITS

1980 ◽  
Vol 87 (2) ◽  
pp. 303-312 ◽  
Author(s):  
P. MARY COTES ◽  
W. A. BARTLETT ◽  
ROSE E. GAINES DAS ◽  
P. FLECKNELL ◽  
R. TERMEER
Keyword(s):  
Growth Hormone ◽  
Human Growth Hormone ◽  
Plasma Levels ◽  
Time Course ◽  
Human Growth ◽  
Daily Injection ◽  
Glycine Buffer ◽  
Hormone Effects ◽  
Rate Of Absorption ◽  
Hypophysectomized Rats

Different methods for administration of human growth hormone (hGH) have been examined with a view to efficient use of the limited amounts of hGH at present available for clinical use. We found that in hypophysectomized rats (1) hGH administered by continuous subcutaneous infusion induced a greater increase in body weight (referred to throughout as growth) than hGH administered by intermittent (daily) injection and (2) intermittent injections of hGH dissolved in 16% gelatin induced more growth than hGH dissolved in a glycine buffer. It was further found that (1) hGH dissolved in 16% gelatin compared with hGH dissolved in a glycine buffer induced lower maximal levels of immunoreactive plasma hGH and between 7 and 9 h after treatment higher plasma levels when injected subcutaneously in rabbits, (2) 125I-labelled hGH added as a tracer to hGH in gelatin was removed more slowly from subcutaneous injection sites in rabbits than 125I-labelled hGH given with hGH in glycine buffer and (3) changes in the ratio of hGH to gelatin had little effect on the time-course of plasma levels of hGH in the rabbit. Addition of the protease inhibitors aprotinin or 6-aminohexanoic acid, to injection of hGH in gelatin or glycine did not induce any consistent increase in plasma levels of hGH.

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