Modulation of Growth Hormone-Releasing Factor Stimulated Growth Hormone Secretion by Plasma Glucose and Free Fatty Acid Concentrations in Sheep

Sartin, James L.; Bartol, Frank F.; Kemppainen, Robert J.; Dieberg, Gudrun; Buxton, Donald F.; Soyoola, Emmanuel

doi:10.1159/000125073

Cited by 45 publications

(24 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Dimethyl pyrazole or nicotinic acid failed to elicit a rise in plasma GH during the intravenous infusion of epinephrine despite a precipitous fall in FFA levels [18]. In addition, exogenous administration of FFA antagonized GRF-induced GH secretion and pharmacological depletion of circulating FFA for at least 2 h facilitated GRFinduced GH secretion [19]. In the present study, plasma GH was suppressed by the infusion of VFA even when plasma FFA decreased.…”

Section: Infusion Experimentscontrasting

confidence: 50%

Effect of Mesenteric Venous Volatile Fatty Acids (VFA) Infusion on GH Secretion in Sheep.

et al. 1997

View full text Add to dashboard Cite

Abstract. The effects of mesenteric venous infusion of acetate, propionate and butyrate mixture (20.3, 40.5 and 81.0 ,umol kg-i mini over 4 h) on the secretion of GH was examined to investigate the effects of an increase in portal volatile fatty acids (VFA) on GH secretion in relation to inhibition of GH secretion after feeding in sheep. The mesenteric venous infusion at the rate of 40.5 tmol kg-i mini increased the portal plasma VFA concentration within the approximate physiological range after feeding. Plasma GH was noticeably suppressed only at the infusion rate of 81.0 tmol kg-i mini and the change in the mean concentration from the base line was significantly less than in the control. Although GRF injection rapidly increased plasma GH, the change in the mean concentration from the base line tended to suppress only at the infusion rate of 81.0 µmol kg-i min-i. Plasma FFA was suppressed in a dose-dependent manner after VFA infusion. The change in the mean concentration from the base line was significantly suppressed only at the infusion rate of 81.0 pmol kg' mini relative to the control infusion, but plasma glucose was unchanged by VFA infusion. It is concluded that because the increase in the portal plasma VFA concentration within the range of feeding did not suppress GH secretion, VFA absorbed by the digestive tract may not play a significant role in suppressing GH secretion after feeding in sheep.

show abstract

Section: Infusion Experimentscontrasting

confidence: 50%

Effect of Mesenteric Venous Volatile Fatty Acids (VFA) Infusion on GH Secretion in Sheep.

et al. 1997

View full text Add to dashboard Cite

show abstract

“…An 18 gauge guide cannula with luer closure stylette was placed into a lateral ventricle 15 mm rostral to the interaural line, 8 mm lateral to midline, and approximately 25 mm ventral from the skull surface of each sheep. Three stainless steel screws were placed in the frontal bone and the cannula was cemented to these screws with dental acrylic, then a plastic tube with a lid was cemented around the cannula (Buxton 1988, Sartin et al 1988. Cannula placement was confirmed at the beginning and the end of this study by taking a radiograph in the lateral aspect immediately after injecting 1 ml of a radioopaque dye (Omnipaque 300; Sterling Drug Inc., New York, NY, USA) into the cannulated ventricle.…”

Section: Animals and Maintenancementioning

confidence: 99%

“…GH was assayed as described previously (Sartin et al 1985(Sartin et al , 1988. Intra-and interassay coefficients of variation (C.V.) were 8·7% and 15·5% respectively.…”

Section: Hormone Analysismentioning

confidence: 99%

Neuropeptide Y restores appetite and alters concentrations of GH after central administration to endotoxic sheep

McMahon

Buxton²,

Elsasser³

et al. 1999

Journal of Endocrinology

View full text Add to dashboard Cite

The objective of this study was to determine whether neuropeptide Y (NPY) and recombinant human interleukin-1 receptor antagonist (IL-1ra) would: first, increase food intake; secondly, decrease concentrations of GH; thirdly, reduce GHRH-induced release of GH; and fourthly, reduce changes to concentrations of IGF-I in plasma during experimental endotoxemia in sheep.Six treatments were given to six castrated male sheep in a 6 6 Latin square treatment order. Osmotic minipumps were implanted at 0 h and a jugular vein was cannulated. Each sheep was continuously infused with saline (0·9%) or lipopolysaccharide (LPS) (20 µg/kg per 24 h, s.c.) at 10 µl/h for 72 h via the osmotic mini-pumps. Blood samples (3 ml) were collected at 15-min intervals from 24 to 33 h. At 26 h, one of three treatments (artificial cerebrospinal fluid, NPY or IL-1ra) was injected i.c.v. within 30 s (0·3 µg/kg), then infused i.c.v. from 26 to 33 h (600 µl/h) at 0·3 µg/kg per h. GHRH was injected i.v. (0·075 µg/kg) at 32 h after which blood samples were collected at 5, 10, 15, 30, 45 and 60 min. Feed intake was reduced up to 50% for 48 h in LPS-treated compared with non-LPS-treated sheep.NPY restored feed intake in LPS-treated sheep and induced hyperphagia in non-LPS-treated sheep from 24 to 48 h. In contrast, IL-1ra did not affect appetite. Injection of NPY increased concentrations of GH from 26 to 27 h, while IL-1ra had no effect. Infusion of NPY suppressed GHRH-induced release of GH. However, no treatment altered pulse secretion parameters of GH. Concentrations of IGF-I were 20% higher at 72 h in LPS-treated sheep given NPY than in sheep treated with LPS alone, and this may reflect increased appetite from 24 to 48 h.We concluded that reduced appetite during endotoxemia is due to down-regulation of an NPY-mediated mechanism. Furthermore, NPY stimulates release of GH in healthy sheep, does not reduce pulse secretion parameters of GH, but does suppress GHRH-induced release of GH in endotoxic sheep. Therefore, NPY may be an important neurotransmitter linking appetite with regulation of GH during endotoxemic and healthy states in sheep.

show abstract

“…These findings indicate the possibility of a feedback regulation system between ACTH and fatty acids. It has also been reported in the ruminant in vivo and in vitro that GH release is inhibited by various fatty acids (Hertelendy & Kipnis 1973, Reynaert et al 1975, Sartin et al 1988, Coxam et al 1989, Estienne et al 1989, Matsunaga et al 1998, 1999, Ishiwata et al 2000.…”

Section: Discussionmentioning

confidence: 94%

Responses induced by arginine-vasopressin injection in the plasma concentrations of adrenocorticotropic hormone, cortisol, growth hormone and metabolites around weaning time in goats

Katoh¹,

Yoshida²,

Kobayashi³

et al. 2005

Journal of Endocrinology

View full text Add to dashboard Cite

In order to assess the biological significance of weaning and water deprivation on the control of plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, growth hormone (GH) and metabolites in response to stimulation with arginine-vasopressin (AVP) and corticotropin-releasing hormone (CRH), we carried out three experiments in which male goats before and after weaning were intravenously injected with AVP or CRH alone, or in combination with each other. In experiment 1, 17-week-old (post-weaning) goats were intravenously injected with AVP or CRH alone at the doses of 0·1, 0·3 and 1·0 nmol/kg body weight (BW). The AVP injection significantly and dose dependently increased plasma levels of ACTH, cortisol, GH and metabolites, whereas the injection with CRH did not cause significant increases in the levels of these parameters. In experiment 2, 4-weekold (pre-weaning) and 13-week-old (post-weaning) goats were injected with either AVP or CRH alone, followed by a combined injection of both secretagogues at a dose of 0·3 nmol/kg BW. Although the basal levels of the hormones and metabolites, with the exception of glucose, were greater in the 4-week-old goats, the hormone responses induced by stimulation with AVP were weaker than those induced in 13-week-old goats. Additionally, there were no responses in any hormone patterns to CRH stimulation in 4-week-old goats. In experiment 3, 13-week-old goats were injected with CRH alone followed by injection with AVP for two consecutive days of water deprivation. The animals were subjected to withdrawal of up to 20% of the total blood volume and water deprivation for up to 28 h. However, no significant differences in plasma ACTH, cortisol or GH levels were observed between days 1 and 2. Based on these results, we concluded that: (1) AVP is a more potent stimulant than CRH in terms of its ability to induce increases in plasma levels of ACTH, cortisol and GH; (2) the role of AVP as a secretagogue of hypothalamus-pituitary-adrenal hormones is strengthened, whereas the ineffective role of CRH remains unaltered, by weaning; (3) acute stress such as massive withdrawal of blood volume and subjection to water deprivation may not be sufficient burdens to alter stress-related hormone levels in young goats.

show abstract

Modulation of Growth Hormone-Releasing Factor Stimulated Growth Hormone Secretion by Plasma Glucose and Free Fatty Acid Concentrations in Sheep

Cited by 45 publications

References 13 publications

Effect of Mesenteric Venous Volatile Fatty Acids (VFA) Infusion on GH Secretion in Sheep.

Effect of Mesenteric Venous Volatile Fatty Acids (VFA) Infusion on GH Secretion in Sheep.

Neuropeptide Y restores appetite and alters concentrations of GH after central administration to endotoxic sheep

Responses induced by arginine-vasopressin injection in the plasma concentrations of adrenocorticotropic hormone, cortisol, growth hormone and metabolites around weaning time in goats

Contact Info

Product

Resources

About