The effect of cold adaptation on kinetics of insulin and growth hormone in heifers

1993 ◽  
Vol 73 (1) ◽  
pp. 33-47 ◽  
Author(s):  
S. L. Scott ◽  
R. J. Christopherson
Keyword(s):  
Growth Hormone ◽  
Cold Adaptation ◽  
Slow Component ◽  
Plasma Concentrations ◽  
Endocrine System ◽  
Insulin Injection ◽  
Metabolic Clearance ◽  
Cold Environment ◽  
Cold Adapted ◽  
Total Turnover

Ten Holstein heifers 1 yr of age were housed in groups of five in temperature-controlled environmental chambers maintained at either 20 °C (warm environment) or − 17 °C (cold environment). Each heifer received an injection of insulin or growth hormone followed by frequent blood sampling. Plasma samples were analyzed for insulin, insulin-like growth factor I (IGF-1), growth hormone, glucagon, triiodothyronine, thyroxine and glucose. Basal plasma concentrations of all hormones except growth hormone and IGF-1 were elevated (P < 0.05) in the cold environment. Kinetic parameters for growth hormone and insulin were calculated using a two-pool model. Both the zero-time intercept and the rate constant for the slow component of growth hormone were lower (P < 0.05) in cold-adapted animals. The total turnover rate of growth hormone in both pools also tended to be reduced by cold adaptation (P < 0.07). The reduction in growth-hormone turnover may be related to the reduced average daily gains that were observed in the cold (P < 0.05). Plasma glucose concentration following both the insulin and growth-hormone injections was higher in the cold-adapted heifers (P < 0.001 and P < 0.05, respectively). The response of glucagon to insulin injection was greater in the cold (P < 0.05), as was the response of IGF-I to growth-hormone injection (P < 0.10). These cold-induced alterations in the endocrine system appear to be directed toward providing substrates, including glucose, for use in thermogenesis rather than growth. Key words: Cold adaptation, growth hormone, insulin, metabolic clearance rate, hormone kinetics, cattle

RELATIONSHIP BETWEEN LAMB BIRTH WEIGHTS AND FETAL PLASMA GROWTH HORMONE AND INSULIN CONCENTRATIONS

1986 ◽  
Vol 66 (4) ◽  
pp. 995-1001
Author(s):  
G. J. MEARS
Keyword(s):  
Growth Hormone ◽  
Fetal Growth ◽  
Plasma Insulin ◽  
Plasma Concentrations ◽  
Maternal Plasma ◽  
Metabolic Clearance ◽  
Plasma Growth Hormone ◽  
Fetal Plasma ◽  
Plasma Gh ◽  
Ovine Fetal

Plasma concentrations of growth hormone (GH) and insulin were monitored in 11 chronically cannulated ovine fetuses and their mothers during the last month of gestation to obtain information on the role that these hormones have in determining fetal growth rate. Maternal plasma GH and insulin concentrations were independent of stage of gestation and lamb birth weights. Fetal plasma insulin concentrations were episodic in nature, independent of stage of gestation, and tended to be higher in fetuses that were heavier at birth. Fetal plasma GH concentrations were only slightly episodic in nature, were tenfold higher than maternal levels at 116–124 d gestation and increased by approximately another 25% prior to parturition. Fetal plasma GH concentrations were negtively correlated with lamb birth weights. In twin preparations, fetal plasma GH concentrations were significantly lower in the twin that was heaviest at birth. The lower GH concentrations found in faster growing fetuses are suggestive of a more rapid metabolic clearance of GH by the tissues of these animals. The results indicate that circulating fetal GH and, possibly, insulin are involved in determining the rate of ovine-fetal growth. Key words: Ovine birth weights, fetal GH, fetal insulin, fetal growth

Influence of nephrectomy on the glucoregulatory response to insulin administration in the rat

1980 ◽  
Vol 58 (3) ◽  
pp. 301-305 ◽  
Author(s):  
Gavino Perez ◽  
Giacomo Carteni ◽  
Biagio Ungaro ◽  
Luigi Saccà
Keyword(s):  
Plasma Concentrations ◽  
Insulin Injection ◽  
Constant Infusion ◽  
Glucose Turnover ◽  
Metabolic Clearance ◽  
The Face ◽  
Plasma Insulin Levels ◽  
Glucagon And Insulin ◽  
Glucose Output

Insulin sensitivity and resistance were examined in vivo in uremic rats by using tracer methods which permit the assessment of "non-steady-state" glucose kinetics. By relating the changes in the rates of glucose output by the liver (Ra), uptake by tissues (Rd), and metabolic clearance (MCR) to immunoreactive glucagon and insulin, it was possible to assess the tissue sensitivity to physiologic and supraphysiologic levels of these two hormones and the site of insulin resistance. The effect of an intravenous injection of insulin (100 mU) on glucose turnover was studied in acutely uremic rats 15 h after bilateral nephrectomy and in sham-operated controls, in the postabsorptive state. Glucose output by the liver and uptake by tissues were determined by the primed constant infusion technique using [3-3H]glucose. Under basal conditions, no significant differences in Ra and Rd between the two groups were observed, while a significant hyperglycemia and a reduced glucose metabolic clearance rate in the face of hyperglucagonemia and normal plasma insulin levels were observed in nephrectomized rats. After insulin injection, the glycemic curves were similar in the two groups, while Ra, Rd, and MCR displayed significantly lower values in nephrectomized rats in the face of higher plasma concentrations of insulin and glucagon. It was concluded that acute uremia in the rat is characterized by a loss of the normal ability of insulin to promote peripheral glucose uptake with retention of hepatic sensitivity to insulin.

Effects of hysterectomy and uterine extracts on growth hormone, somatomedin, prolactin, thyrotrophin and thyroid hormones in adult rats

1983 ◽  
Vol 103 (2) ◽  
pp. 172-179 ◽  
Author(s):  
J. Bíró ◽  
E. M. Ritzén ◽  
K. Hall ◽  
P. Eneroth
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Plasma Concentrations ◽  
Endocrine System ◽  
Thyroid Stimulating Hormone ◽  
The Body ◽  
Biologically Active ◽  
Female Rats ◽  
Adult Rats ◽  
Plasma Gh

Abstract. Plasma concentrations and anterior pituitary content of growth hormone (rGH), thyroid stimulating hormone (rTSH), and rat prolactin (rPrl) as well as the plasma concentrations of triiodothyronine (T3), thyroxine (T4) and somatomedin A (SM-A) have been determined in intact, castrated or hysterectomized adult rats with and without treatment with steroid-free, crude uterine extracts. Hysterectomy caused a significant increase in the plasma GH but decrease in the plasma TSH concentrations. Injection of crude, steroid-free uterine extracts for 14 days had the following effects: decreased plasma GH concentration of intact rat and anterior pituitary GH content of both intact and castrated animals; increased plasma TSH and T3 concentrations above the ovariectomized control; decreased pituitary content of prolactin in castrated rats. The plasma levels of immunoreactive somatomedins A were negatively correlated to the plasma GH concentrations but positively correlated to the body weight. It was concluded that the uterus is not only a target for different endocrine influences but contains biologically active, non-steroidal substances which have a complex effect on the endocrine system of adult, female rats.

Precooling of peripheral arterial blood in cold-adapted and warm-adapted rabbits

1965 ◽  
Vol 20 (6) ◽  
pp. 1133-1135 ◽  
Author(s):  
Nishio Honda
Keyword(s):  
Heat Exchange ◽  
Temperature Regulation ◽  
Cold Adaptation ◽  
The Body ◽  
Cold Environment ◽  
Cold Adapted ◽  
Warm Environment ◽  
Arterial Blood ◽  
Peripheral Arterial

The role of precooling of peripheral arterial blood in temperature regulation has been studied in cold-adapted and warm-adapted rabbits. It was found that precooling of arterial blood during its flow from the interior to the surface (ear) of the body in a cold environment is more marked in the cold-adapted rabbits than in warm-adapted rabbits. In a warm environment no difference was found between the two groups. countercurrent heat exchange; cold adaptation or acclimation Submitted on February 8, 1965

ELIMINATION OF INFUSED ARGININE-VASOPRESSIN AND ITS LONG-ACTING DEAMINATED ANALOGUE IN RATS

1978 ◽  
Vol 78 (2) ◽  
pp. 179-186 ◽  
Author(s):  
DIANA GAZIS ◽  
W. H. SAWYER
Keyword(s):  
Arginine Vasopressin ◽  
Plasma Concentrations ◽  
Metabolic Clearance ◽  
Prolonged Infusion ◽  
Exponential Functions ◽  
Antidiuretic Effect ◽  
Long Acting ◽  
Deamino Arginine Vasopressin

SUMMARY Arginine-vasopressin (AVP) and deamino-arginine-vasopressin (dAVP) were infused into rats. When the concentrations of the two peptides were steady, the rate of clearance of AVP from the plasma was six times the rate of clearance of dAVP. Only 6% of the infused AVP was excreted unchanged in the urine, whereas approximately 100% of the dAVP was excreted. When the infusions were stopped, AVP disappeared from the plasma much more rapidly than dAVP. The plasma concentrations of the two peptides did not decay as simple exponential functions, suggesting that both AVP and dAVP entered a slowly exchanging compartment or compartments during prolonged infusion. These differences in the metabolic clearance of AVP and dAVP may well explain the prolonged antidiuretic effect of dAVP in rats.

Increased ACTH response to corticotropin-releasing factor in cold-adapted rats in vivo

1989 ◽  
Vol 257 (3) ◽  
pp. E336-E339 ◽  
Author(s):  
A. Uehara ◽  
Y. Habara ◽  
A. Kuroshima ◽  
C. Sekiya ◽  
Y. Takasugi ◽  
...  
Keyword(s):  
Stress Responses ◽  
Cold Adaptation ◽  
Corticotropin Releasing Factor ◽  
Plasma Acth ◽  
Cold Adapted ◽  
Repeated Restraint Stress ◽  
Cross Adaptation ◽  
Freely Moving ◽  
Increased Activity

We have recently reported that chronically repeated restraint stress results in improved cold tolerance in rats via an increased activity of nonshivering thermogenesis, a characteristic metabolic change observed during cold adaptation, suggesting the presence of cross-adaptation between cold and stress. It is well established that the hypothalamic-pituitary-adrenal (HPA) axis is activated in various stress responses. In the present study, therefore, we examined whether cold adaptation would alter the adrenocorticotropic hormone (ACTH)-releasing state in vivo using freely moving, conscious rats chronically implanted with intra-atrial cannulas. There was no difference in the basal levels of plasma ACTH between warm control and cold-adapted rats. On the other hand, the ACTH response to the intravenous administration of corticotropin-releasing factor (CRF; 2 micrograms/animal) was significantly elevated in cold-adapted rats. However, the injection of 10 micrograms of CRF, which was considered as a dose to elicit the maximal ACTH response, resulted in similar ACTH release patterns between the two groups. These changes in the responsiveness of ACTH secretion have been observed in rats chronically exposed to stressful conditions. The results demonstrated in the present study, therefore, provide further evidence for our hypothesis that there may exist cross-adaptation between cold and nonthermal stress.

The Effects of Thyroxine and Isopropylnoradrenaline on Cytochrome Oxidase Activity in Brown Adipose Tissue

1973 ◽  
Vol 51 (10) ◽  
pp. 751-758 ◽  
Author(s):  
H. M. C. Heick ◽  
C. Vachon ◽  
Mary Ann Kallai ◽  
Nicole Bégin-Heick ◽  
J. LeBlanc
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Protein Content ◽  
Cytochrome Oxidase ◽  
Cold Adaptation ◽  
Metabolic Response ◽  
Mitochondrial Enzymes ◽  
Cold Adapted ◽  
Brown Adipose ◽  
Hormonal Treatments

Groups of animals were treated with injections of isopropylnoradrenaline, thyroxine, or both hormones together. The effects of these hormonal treatments on the size, protein content, and level of some mitochondrial enzymes, in particular the cytochrome oxidase, were determined and compared to the effect on these parameters produced by cold adaptation. The changes observed were correlated with the resistance of the animals to cold stress and with their metabolic response to injections of isopropylnoradrenaline. All treatments increased the size of the brown adipose tissue. Whereas thyroxine had little effect on the protein content and cytochrome oxidase, both isopropylnoradrenaline and cold adaptation produced increases in these parameters. It appears that the isopropylnoradrenaline-treated animals mimic more closely the cold-adapted animals than do those with thyroxine treatment. However, the isopropylnoradrenaline-treated animals are not as resistant to cold as the cold-adapted animals.

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