scholarly journals GH and cortisol rebound rise during and following a somatostatin infusion: studies in dogs with the use of a GH-releasing peptide

2002 ◽  
Vol 174 (3) ◽  
pp. 387-394 ◽  
Author(s):  
AE Rigamonti ◽  
SM Bonomo ◽  
SG Cella ◽  
EE Muller
Keyword(s):  
Hpa Axis ◽  
Plasma Cortisol ◽  
Cortisol Response ◽  
Marked Rise ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Combined Administration ◽  
Cortisol Responses ◽  
Plasma Gh

GH-releasing peptides (GHRPs), a class of small synthetic peptide and non-peptide compounds, act on specific receptors at both the pituitary and the hypothalamic level to stimulate GH release in both humans and other animals. GHRPs, like corticotropin-releasing hormone (CRH), also possess acute ACTH- and cortisol-releasing activity, although the mechanisms underlying the stimulatory effect of GHRPs on the hypothalamo-pituitary-adrenal (HPA) axis are still unclear. In recent years, studies in humans and other animals have provided evidence that the rebound GH rise which follows withdrawal of an infusion of somatostatin (SS) (SSIW) is due, at least in part, to the functional activation of GH-releasing hormone (GHRH) neurons of the recipient organism. Unexpectedly, in humans, SS infusion, at a dose inhibiting basal GH secretion, has been associated with an activation of the HPA axis, leading to the hypothesis that this response was mediated, at least in part, by a central nervous system ACTH-releasing mechanism activated by the SS-induced decrease in GH secretion. Interestingly, the rebound GH rise which follows SSIW was magnified by the administration, before SS withdrawal, of a GHRP, implying that the SSIW approach could also be exploited to investigate in vivo the functional interaction in the process of GH and/or ACTH/cortisol secretion between endogenous GHRH (and/or other ACTH-releasing mechanisms) and GHRPs. In the present study, six young beagle dogs were given, on different occasions, at the beginning and at the end of a 3-h i.v. infusion of SS or saline (SAL), a bolus of physiological SAL or a GHRP compound, EP51216. SSIW induced a GH rebound rise without affecting plasma cortisol concentrations, while the withdrawal of SAL infusion was ineffective on either hormone paradigm. Administration of EP51216 at the beginning of SAL infusion evoked release of both GH and cortisol, whereas EP51216 administration at the withdrawal of SAL infusion evoked somatotroph and cortisol responses which were reduced in amplitude and duration. SS infusion significantly reduced the secretion of GH elicited by EP51216 but did not affect the rise of plasma cortisol levels. Interestingly, SSIW resulted in a marked enhancement of the somatotroph and cortisol responses evoked by EP51216. The marked rise of plasma GH levels induced by the GHRP after SSIW recalled that occurring after acute combined administration of recombinant human GHRH and EP51216, implying that exogenously delivered GHRP had synergized with the endogenous GHRH release triggered by SSIW. In contrast, acute combined administration of GHRH and the GHRP induced a cortisol response not different from that induced by GHRP alone, indicating that endogenous GHRH release was not involved in the enhanced cortisol response following EP51216 administration after SSIW. Similarly, the direct involvement of endogenous CRH could be ruled out, since i.v. administration of ovine CRH after SSIW evoked cortisol peak levels not different from those evoked by CRH at the withdrawal of SAL infusion. In conclusion, enhancement of the GH response to EP51216 alone by SSIW, to an extent reminiscent of that following combined administration of GHRH and EP61216, reinforces the view that SSIW elicits release of endogenous GHRH. Further studies are indeed necessary for a better understanding of the mechanisms underlying the enhanced cortisol response, since from now on the involvement of endogenous GHRH or CRH can be ruled out.

Physiological control of growth hormone secretion by thyrotrophin-releasing hormone in the domestic fowl

1985 ◽  
Vol 105 (3) ◽  
pp. 351-355 ◽  
Author(s):  
H. Klandorf ◽  
S. Harvey ◽  
H. M. Fraser
Keyword(s):  
Domestic Fowl ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Physiological Control ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Normal Sheep Serum ◽  
Plasma Gh

ABSTRACT Immature cockerels (4- to 5-weeks old) were passively immunized, with antiserum raised in sheep, against thyrotrophin-releasing hormone (TRH). The administration of TRH antiserum (anti-TRH) at doses of 0·5, 1·0 or 2·0 ml/kg lowered, within 1 h, the basal concentration of plasma GH for at least 24 h. The administration of normal sheep serum had no significant effect on the GH concentration in control birds. Although the GH response to TRH (1·0 or 10·0 μg/kg) was not impaired in birds treated 1 h previously with anti-TRH, prior incubation (at 39 °C for 1 h) of TRH (20 μg/ml) with an equal volume of anti-TRH completely suppressed the stimulatory effect of TRH (10 pg/kg) on GH secretion in vivo. These results suggest that TRH is physiologically involved in the hypothalamic control of GH secretion in the domestic fowl. J. Endocr. (1985) 105, 351–355

Growth hormone (GH) responses to the combined administration of GH-releasing hormone plus GH-releasing peptide 6 in adults with GH deficiency

1995 ◽  
Vol 132 (6) ◽  
pp. 712-715 ◽  
Author(s):  
A Leal-Cerro ◽  
E Garcia ◽  
R Astorga ◽  
FF Casanueva ◽  
C Dieguez
Keyword(s):  
Growth Hormone ◽  
Gh Deficiency ◽  
Hormone Deficiency ◽  
Santiago De Compostela ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Factor I ◽  
Gh Replacement ◽  
Combined Administration ◽  
Plasma Gh

Leal-Cerro A, Garcia E, Astorga R, Casanueva FF, Dieguez C. Growth hormone (GH) responses to the combined administration of GH-releasing hormone plus GH-releasing peptide 6 in adults with GH deficiency. Eur J Endocrinol 1995;132:712–5. ISSN 0804–4643 In recent years the health problems of adults with growth hormone deficiency (GHD) and the benefits of GH replacement therapy have received considerable attention. However, the reliability of conventional GH tests in the assessment of pituitary GH reserve in this group of patients is still controversial. In this study, we assessed GH secretion after the combined administration of GH-releasing hormone (GHRH) (1 μg/kg iv) and GH-releasing peptide 6 (GHRP-6, 1 μg/kg iv) in adult patients diagnosed with GHD by conventional GH testing, and correlate this response with insulin-like growth factor I levels. Twenty-one subjects (13 male, 8 female) with long-standing diagnosis of GHD aged 21–54 years were studied. In 13 subjects GH responses to GHRH plus GHRP-6 were markedly reduced (peak GH response <10 mU/I), whereas in the remaining eight the response was greater (range 11–100 mU/l), In conclusion, our data show that combined administration of GHRH plus GHRP-6 elicited a significant increase in plasma GH levels in about 40% of patients diagnosed with GHD by conventional GH testing. C Dieguez, PO Box 563, 15700 Santiago de Compostela, Spain

Mediation by the central nervous system is critical to the in vivo activity of the GH secretagogue L-692,585

1996 ◽  
Vol 148 (2) ◽  
pp. 371-380 ◽  
Author(s):  
G J Hickey ◽  
J Drisko ◽  
T Faidley ◽  
C Chang ◽  
L L Anderson ◽  
...  
Keyword(s):  
Intact Animal ◽  
Control Group ◽  
Cortisol Response ◽  
Gh Secretion ◽  
Significant Difference ◽  
Before And After ◽  
The Central Nervous System ◽  
Cortisol Responses ◽  
Inhibitory Tone

Abstract To investigate the effect of hypophyseal transection (HST) on GH secretagogue activity of the non-peptidyl GH secretagogue L-692,585 in the conscious pig, male castrated swine were randomly assigned to either a hypophyseal stalk transection group (HST; n=3) or to a sham-operated control group (SOC; n=3). Treatments administered were L-692,585 (100 γg/kg), human GH-releasing factor(1–29)NH2 (GRF; 20 γg/kg) or L-692,585 (100 γg/kg) + GRF (20 γg/kg) on days −7 to −3 before surgery and days +3 to +8 after surgery. To evaluate the integrity of the pituitary gland, the animals were challenged with corticotropin-releasing hormone (CRH; 150 γg) or GnRH (150 ng/kg) both before and after surgery. Blood was collected from −60 to +180 min post treatment and assayed for GH, cortisol and LH. Before surgery, no significant difference (P>0·05) in peak GH response (ng/ml) was present between the two groups (SOC vs HST) in response to L-692,585 (101 ± 12 vs 71 ± 9) or L-692,585 + GRF (171 ± 21 vs 174 ± 21). Only two out of three SOC vs three out of three HST pigs responded to GRF (13 ± 2 vs 25 ± 3) resulting in a significant difference between groups. Following surgery, significant differences were present in peak GH response (ng/ml) between SOC and HST groups following L-692,585 (79 ± 6 vs 13·8 ± 1·0); however, the response to L-692,585 + GRF was similar (115 ± 8 vs 94 ± 7). All animals responded to GRF; however, a significant difference was present between groups due to the magnitude of the responses. Whereas the cortisol responses (ng/ml) to L-692,585 in the SOC and HST groups were similar before surgery, a significant difference was present after surgery (44·4 ± 6·4 vs 14·6 ± 2·1). No significant difference was noted between the HST and SOC groups in response to CRH or GnRH either before or after surgery. These results indicated that L-692,585 induced an immediate GH response in the intact animal in contrast to GRF where the GH release was variable. L-692,585 also stimulated an immediate increase in cortisol levels. Transection of the hypophyseal stalk dramatically decreased but did not ablate the GH or cortisol response to L-692,585. Co-administration of L-692,585 + GRF induced an immediate GH response of similar magnitude in the intact and HST animal. We conclude that L-692,585 has a direct but limited action at the level of the pituitary and that an intact hypophyseal stalk is required for a maximal GH and cortisol response. L-692,585 acts with GRF at the level of the pituitary to induce a maximal GH response. These findings suggest that L-692,585 stimulates GH secretion by acting in combination with GRF and interrupting the inhibitory tone of somatostatin on the somatotroph. Journal of Endocrinology (1996) 148, 371–380

scholarly journals Effects of sex and early maternal abuse on adrenocorticotropin hormone and cortisol responses to the corticotropin-releasing hormone challenge during the first 3 years of life in group-living rhesus monkeys

2010 ◽  
Vol 22 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Mar M. Sanchez ◽  
Kai Mccormack ◽  
Alison P. Grand ◽  
Richelle Fulks ◽  
Anne Graff ◽  
...  
Keyword(s):  
Sex Differences ◽  
Hpa Axis ◽  
Rhesus Monkeys ◽  
Group Living ◽  
Cortisol Response ◽  
Corticotropin Releasing Hormone ◽  
Long Term Effects ◽  
Releasing Hormone ◽  
Cortisol Responses

AbstractIn this study we investigated the development of the hypothalamic–pituitary–adrenal (HPA) axis in 21 group-living rhesus monkeys infants that were physically abused by their mothers in the first few months of life and in 21 nonabused controls. Cortisol and adrenocorticotropin hormone (ACTH) responses to a corticotropin-releasing hormone (CRH) challenge were assessed at 6-month intervals during the subjects' first 3 years of life. Abused infants exhibited greater cortisol responses to CRH than controls across the 3 years. Abused infants also exhibited blunted ACTH secretion in response to CRH, especially at 6 months of age. Although there were no significant sex differences in abuse experienced early in life, females showed a greater cortisol response to CRH than males at all ages. There were no significant sex differences in the ACTH response to CRH, or significant interactions between sex and abuse in the ACTH or cortisol response. Our findings suggest that early parental maltreatment results in greater adrenocortical, and possibly also pituitary, responsiveness to challenges later in life. These long-term alterations in neuroendocrine function may be one the mechanisms through which infant abuse results in later psychopathologies. Our study also suggests that there are developmental sex differences in adrenal function that occur irrespective of early stressful experience. The results of this study can enhance our understanding of the long-term effects of child maltreatment as well as our knowledge of the development of the HPA axis in human and nonhuman primates.

Altered adrenocorticotropin and cortisol response to corticotropin-releasing hormone in HIV-1 infection

1995 ◽  
Vol 133 (2) ◽  
pp. 173-179 ◽  
Author(s):  
Alberto Biglino ◽  
Paolo Limone ◽  
Brunella Forno ◽  
Annamaria Pollono ◽  
Giuseppe Cariti ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Hpa Axis ◽  
Stage Iv ◽  
Cortisol Response ◽  
Corticotropin Releasing Hormone ◽  
Releasing Hormone ◽  
Positive Linear Correlation ◽  
Healthy Control ◽  
Cortisol Responses ◽  
Adrenal Response

Biglino A, Limone P, Forno B, Pollono A, Cariti G, Molinatti GM, Gioannini P. Altered adrenocorticotropin and cortisol response to corticotropin-releasing hormone in HIV-I infection. Eur J Endocrinol 1995;133:173-9. ISSN 0804-4643 Alterations of the hypothalamic-pituitary-adrenal (HPA) axis are common in HIV infection. To characterize further the site of these derangements and their possible causes, eight male drug addicts with symptomatic HIV infection (stage IV C2) underwent the following investigations: repeated baseline determinations of cortisol, adrenocorticotropin (ACTH), interleukin 1β (IL-1β), IL-6 and interferon alpha (IFN-α): and ovine corticotropin-releasing hormone (CRH) test (100 μg IV) for ACTH and cortisol determinations. Baseline cortisol levels were either normal or elevated in all patients. A significant positive linear correlation was found between baseline levels of cortisol and both IL-6 (r=0.955; p<0.001) and IL-1β (r=0.863; p<0.005), but not between cortisol and ACTH or between ACTH and circulating cytokines. Both ACTH and cortisol responses to CRH were nearly absent in six out of eight patients, and delayed in the others. The areas under the curves of both ACTH and cortisol after CRH were significantly lower in HIV patients than in a group of eight healthy control subjects (p=0.0157 for ACTH and p=0.046 for cortisol). Our data suggest the possibility of an inappropriate stimulation of the HPA axis in symptomatic HIV infection by HIV-induced release of cytokines, with a blunted pituitary and adrenal response to CRH. Paolo Limone, Institute of Internal Medicine, University of Torino, C.so AM Dogliotti 14, 10126 Torino, Italy

Influence of endogenous cholinergic tone and α-adrenergic pathways on growth hormone responses to His-d-Trp-Ala-Trp-d-Phe-Lys-NH2 in the dog

1993 ◽  
Vol 138 (2) ◽  
pp. 211-218 ◽  
Author(s):  
J. Muruais ◽  
A. Peñalva ◽  
C. Dieguez ◽  
F. F. Casanueva
Keyword(s):  
Growth Hormone ◽  
Inhibitory Effect ◽  
Adrenergic Agonist ◽  
Stimulatory Action ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Combined Administration ◽  
Cholinergic Tone ◽  
Basal Plasma ◽  
Plasma Gh

ABSTRACT His-d-Trp-Ala-Trp-d-Phe-Lys-NH2 (GHRP-6) is a synthetic peptide unrelated to any known hypothalamic-releasing hormone including growth hormone-releasing hormone (GHRH). Interestingly, this peptide induces a dose-related increase in plasma GH levels in all species tested so far. The aim of this study was to investigate the action of GHRP-6 alone or in combination with GHRH on GH release in dogs. In addition, the activation or blockade of endogenous cholinergic tone and α-1 adrenoceptors on GHRP-6-stimulated GH secretion was assessed. In adult Beagle dogs (n = 10), GHRP-6 (90 μg i.v.) increased basal GH levels from 2·6 ± 1·5 to 14·4 ± 3·1 μg/l (mean ± s.e.m.) after 15 min. GHRH (50 μg i.v.) induced a GH peak of 9·7 ± 2·2 μg/l at 15 min. The combined administration of GHRP-6 and GHRH strikingly potentiated canine GH release with a peak of 54 ± 9·0 μg/l (P <0·01). Pretreatment with the cholinergic agonist pyridostigmine (30 mg per os) increased GHRP-6-stimulated GH secretion (37·9 ± 10·1 μg/l P <0·05), while the muscarinic blocker atropine (100 μg i.v.) completely abolished (GH peak lower than 2 μg/l) the stimulatory action of GHRP-6. On the other hand, administration of the α-2 adrenergic agonist clonidine (4 pg/kg i.v.) increased basal plasma GH levels without affecting GH responses to GHRP-6. Finally, while the α-1 adrenergic agonist methoxamine (5 mg i.v.) did not significantly increase GH responses to GHRP-6, administration of the α-1 adrenoceptor antagonist prazosin (20 mg i.v.) reduced GHRP-6-induced GH secretion (area under curve, 206 ± 39 vs 557 ± 172, P <0·05). In summary, the synergistic effect of the combined administration of maximal doses of GHRP-6 and GHRH suggests that these two peptides act through different mechanisms. The finding that cholinergic drugs were able to modulate the GH secretion elicited by GHRP-6 argues against the hypothesis that such a peptide acts by influencing hypothalamic somatostatin release and suggests that it acts directly at the pituitary level. Finally, the unexpected lack of effect of clonidine and the inhibitory effect of prazosin on GHRP-6-induced GH secretion suggests that the role of α-adrenergic pathways in GH secretion is more complex than previously thought. Journal of Endocrinology (1993) 138, 211–218

Biological activity of adrenocorticotropic hormone precursors on ovine adrenal cells

1995 ◽  
Vol 268 (4) ◽  
pp. E623-E629 ◽  
Author(s):  
J. Schwartz ◽  
F. Kleftogiannis ◽  
R. Jacobs ◽  
G. D. Thorburn ◽  
S. R. Crosby ◽  
...  
Keyword(s):  
Biological Activity ◽  
Plasma Cortisol ◽  
Inhibitory Action ◽  
Adrenocorticotropic Hormone ◽  
Physiological Role ◽  
Cortisol Response ◽  
Adrenal Cells ◽  
Fetal Cells ◽  
Fetal Plasma ◽  
Cortisol Responses

Adrenocorticotropic hormone (ACTH) is synthesized in the corticotrophs as a precursor, pro-opiomelanocortin (POMC), which is processed via proACTH to ACTH. Both precursors and ACTH are secreted. Although the steroidogenic activity of ACTH is well characterized, that of the precursors is not. This study assessed the capacity of POMC and proACTH to alter cortisol synthesis. POMC and proACTH were prepared by subjecting medium, conditioned by exposure to DMS-79 cells, to Sephadex chromatography, and the bioactivity was assessed in cultured-dissociated ovine adrenal cells. Alone neither POMC (< or = 2.6 nM) nor proACTH (< or = 0.7 nM) showed any consistent acute (6 h) stimulatory or inhibitory action on cortisol in either fetal or adult cells. In contrast, in fetal cells the precursors inhibited steroidogenic response to ACTH-(1-24). POMC at 2.6 nM, but not lower concentrations, decreased the cortisol responses to 0.01, 0.1, and 1 nM ACTH by at least 50%. ProACTH (0.70 and 0.23 nM) decreased the responses to ACTH at 0.01 nM by 89 and 67%, respectively, and at 0.1 nM by 49 and 34%, respectively. At 1 nM ACTH only 0.7 nM proACTH decreased the response to ACTH (by 69%). In contrast, in adult adrenal cells, the precursors did not significantly reduce the response to ACTH (range 0.01-1 nM). Therefore, these data indicate that POMC and proACTH can inhibit the cortisol response to ACTH in fetal adrenal cells, an effect that is concentration dependent. The data suggest that precursors may play a physiological role, possibly regulating fetal plasma cortisol concentrations.

scholarly journals From growth hormone-releasing peptides to ghrelin: discovery of new modulators of GH secretion

2006 ◽  
Vol 50 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Ana Maria J. Lengyel
Keyword(s):  
Growth Hormone ◽  
Protein Kinase ◽  
C Protein ◽  
Releasing Hormone ◽  
Gh Secretagogues ◽  
Main Site ◽  
Gh Secretion ◽  
Kinase C ◽  
Growth Hormone Releasing Peptides

Growth hormone (GH)-releasing hormone and somatostatin modulate GH secretion. A third mechanism has been discovered in the last decade, involving the action of GH secretagogues. Ghrelin is a new acylated peptide produced mainly by the stomach, but also synthesized in the hypothalamus. This compound increases both GH release and food intake. The relative roles of hypothalamic and circulating ghrelin on GH secretion are still unknown. Endogenous ghrelin might amplify the basic pattern of GH secretion, optimizing somatotroph responsiveness to GH-releasing hormone. This peptide activates multiple interdependent intracellular pathways at the somatotroph, involving protein kinase C, protein kinase A and extracellular calcium systems. However, as ghrelin induces a greater release of GH in vivo, its main site of action is the hypothalamus. In this paper we review the available data on the discovery of ghrelin, the mechanisms of action and possible physiological roles of GH secretagogues and ghrelin on GH secretion, and, finally, the regulation of GH release in man after intravenous administration of these peptides.

scholarly journals An initial exploration of in vivo hair cortisol responses to a brief pain stressor: latency, localization and independence effects

2009 ◽  
pp. 757-761
Author(s):  
CF Sharpley ◽  
KG Kauter ◽  
JR McFarlane
Keyword(s):  
Hpa Axis ◽  
Cold Pressor Test ◽  
Cold Pressor ◽  
Hair Follicles ◽  
Repeated Measurements ◽  
Single Observation ◽  
Target Organs ◽  
Cortisol Responses

Cortisol is secreted by the central hypothalamo-pituitary-adrenal axis and affects many target organs and tissues, particularly in response to stressor demands and infection. Recent data reporting cortisol synthesis in hair follicles have shown the existence of a parallel “peripheral” HPA-axis. However, although there is evidence from in vitro studies and single-observation comparisons between groups that cortisol from hair follicles reflects endocrine changes associated with stressor demands, there are no reports to date of repeated measurements of in vivo cortisol responsivity in hair to transitory stressors. This issue was investigated with three males who underwent 1 min cold pressor test (CP). Cortisol response in hair to stressor demand appears to be (a) swift but transitory, (b) localized to the site of the demand and (c) independent of central HPA-axis activity.

Consistent Reduction of ACTH responses to stimulation with CRH, Vasopressin and Hypoglycaemia in Patients with Major Depression

1989 ◽  
Vol 155 (4) ◽  
pp. 468-478 ◽  
Author(s):  
Roger G. Kathol ◽  
Richard S. Jaeckle ◽  
Juan F. Lopez ◽  
William H. Meller
Keyword(s):  
Major Depression ◽  
Hpa Axis ◽  
Negative Correlation ◽  
Arginine Vasopressin ◽  
Corticotropin Releasing Hormone ◽  
Hypothalamic Pituitary Adrenal ◽  
Releasing Hormone ◽  
Control Subjects ◽  
Basal Cortisol ◽  
Cortisol Responses

Eleven patients with major depression and 12 control subjects were administered corticotropin-releasing hormone (CRH), aqueous arginine vasopressin (AVP), and insulin hypoglycaemia (IH) to test for differences in hypothalamic–pituitary–adrenal (HPA) axis function. Patients with major depression demonstrated lower ACTH responses to CRH when compared with controls, and a trend toward such after administration of AVP. Despite lower ACTH responses in patients with depression, there were no differences in Cortisol responses to these stimuli. In the CRH and AVP tests, there was no correlation between the basal Cortisol and ACTH responses in either controls or patients, but in the IH test there was a negative correlation between these responses for both groups. The ACTH responses to CRH and AVP were positively correlated in controls and patients. Cortisol responses to all three provocative stimuli were positively correlated in both subject groups. These findings are consistent with the hypothesis that hypothalamic or supra-hypothalamic overactivity may be involved in the development of HPA-axis abnormalities in patients with depression.

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