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Rizvi SSR, Altaf S, Latif S, Naseem AA, Afzal M, Qayyum M. Chronic orchidectomy does not influence the sensitivity of the pituitary somatotropes to varying doses of GHRH administered intravenously to the adult male rhesus monkey. Life Sci 2004; 75:1041-50. [PMID: 15207652 DOI: 10.1016/j.lfs.2003.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Accepted: 12/12/2003] [Indexed: 11/19/2022]
Abstract
In the present study, the pituitary growth hormone (GH) response to graded doses of GH-releasing hormone (GHRH) was determined in intact (n = 3) and chronically orchidectomized (n = 3) adult rhesus monkeys (Mucaca mulatta). GHRH in doses of 0, 6.25, 12.5 and 25 microg/kg BW was infused through a teflon cannula implanted in the saphenous vein. Blood samples were collected 60 min before and 90 min after the injection of the neurohormone at 15 min intervals. All bleedings were carried out under ketamine hydrochloride anesthesia. The plasma levels of GH were determined by using AutoDELFIA time-resolved flouroimmunoassay, whereas plasma levels of testosterone and estradiol were determined using specific radioimmunoassay systems. The GH responses to GHRH were not significantly different between intact and chronically orchidectomized monkeys at any of the dose levels tested (p > 0.05). The administration of GHRH resulted in a significant (p < 0.05) stimulation of GH secretion at all the doses tested and in both the groups studied. In both intact and orchidectomized animals, the greatest response was observed at 6.25 microg/kg and no further increase was noted with the higher doses of GHRH. In conclusion, the present study suggests that chronic orchidectomy does not influence the sensitivity of the pituitary somatotropes to GHRH stimulation implying that the responsiveness of the pituitary somatotropes to GHRH is independent of testicular steroid modulation.
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Affiliation(s)
- S S R Rizvi
- Pakistan Science Foundation, Constitution Avenue, G-5/2, Islamabad, Pakistan.
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2
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Abstract
The study of psychoneuroendocrinology of schizophrenia has yielded an extensive but inconclusive body of data. Investigations to date have been limited by several factors, including the confounding effects of neuroleptic drugs, methodological limitations, and lack of appreciation for the heterogeneity of the illness. Previously, the focus of research has been on the measurement of anterior pituitary hormones, guided by the assumptions that these hormones are regulated by the central nervous system (CNS) to a significant degree and that the unique anatomic relationship of the pituitary gland to the hypothalamus and the CNS is potentially relevant. Patients with schizophrenia do appear to have distinct endocrinologic profiles. However, although the hormonal differences between patients with schizophrenia and the general population appear to be subtle in magnitude. Nonetheless, investigation, and the exploration of the possible effect of gonadal and posterior pituitary hormones merits particular attention.
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Affiliation(s)
- C E Marx
- Department of Psychiatry, University of North Carolina, Chapel Hill, USA
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3
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Bossé R, Fumagalli F, Jaber M, Giros B, Gainetdinov RR, Wetsel WC, Missale C, Caron MG. Anterior pituitary hypoplasia and dwarfism in mice lacking the dopamine transporter. Neuron 1997; 19:127-38. [PMID: 9247269 DOI: 10.1016/s0896-6273(00)80353-0] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Deletion of the dopamine transporter (DAT) results in increased dopaminergic tone, anterior pituitary hypoplasia, dwarfism, and an inability to lactate. DAT elimination alters the spatial distribution and dramatically reduces the numbers of lactotrophs and somatotrophs in the pituitary. Despite having normal circulating levels of growth hormone and prolactin in blood, hypoplastic glands from DAT-/- mice fail to respond to secretagog stimulation. The effects of DAT deletion on pituitary function result from elevated DA levels that down-regulate the lactotroph D2 DA receptors and depress hypothalamic growth hormone-releasing hormone content. These results reveal an unexpected and important role or DA in the control of developmental events in the pituitary gland and assign a critical role for hypothalamic DA reuptake in regulating these events.
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Affiliation(s)
- R Bossé
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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4
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degli Uberti EC, Salvadori S, Trasforini G, Ambrosio MR, Margutti A, Bondanelli M, Rossi R, Valentini A. Differential effects of deltorphin on arginine and galanin-induced growth hormone secretion in healthy man. REGULATORY PEPTIDES 1995; 58:41-6. [PMID: 8570858 DOI: 10.1016/0167-0115(95)00057-i] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recently we demonstrated the inhibitory action on Growth Hormone (GH) secretion of an opioid heptapeptide, deltorphin (DT), that is highly selective in binding delta-opioid receptors. To investigate the possible mechanism leading to the decrease in GH secretion by specific activation of delta-opioidergic pathway in man, we compared, in normal subjects, the effect of DT on GH secretion responses to two different GH secretagogues, namely arginine (ARG) and galanin (GAL). DT completely blunted the GH response to ARG, whereas it attenuated the GH response to GAL, but not at a statistically significant level. We suggest that the specific activation of delta-opioid receptors in man may exert an inhibitory influence on GH secretion principally by modulating endogenous hypothalamic somatostatin (SRIH) release.
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5
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Abstract
Glucocorticoids (GCs) modulate the somatotropic axis at a genomic and a non-genomic level. Critical concentrations of steroids not only determine somatotrope differentiation but also enhance growth hormone (GH) gene expression. At a cellular level GH-releasing hormone (GHRH) and somatostatin (SS) are the two principal neuropeptides involved in the release of GH. In vitro data indicates that steroids enhance GH release by altering the affinity and the density of GHRH receptors. In addition, they reduce the sensitivity of the somatotrope to SS and decrease IGF-1 induced negative feedback on GH secretion. The net effect is an enhancement of GH release.
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Affiliation(s)
- J H Thakore
- Dept. of Psychological Medicine, St Bartholomew's Hospital, London
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6
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Abstract
In eight healthy volunteers, basal and arginine-stimulated plasma glucose and growth hormone levels were determined during administration of a placebo and after 3 days of ibuprofen (800 mg four times daily). Ibuprofen had no significant effect on basal or stimulated plasma glucose or growth hormone levels. As is not the case with indomethacin, ibuprofen fails to increase basal and arginine-stimulated plasma growth hormone levels. This suggests that the effect of indomethacin on growth hormone secretion is due to a mechanism unrelated to inhibition of prostaglandin synthesis.
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Affiliation(s)
- J K Schmitt
- Department of Veterans Affairs Medical Center, Medical Service, Richmond, VA 23249
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7
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Heuser IJ, Baronti F, Marin CA, Ma N, Merriam GR, Chase TN, Mouradian MM. Growth hormone secretion in Alzheimer's disease: 24-hour profile of basal levels and response to stimulation and suppression studies. Neurobiol Aging 1992; 13:255-60. [PMID: 1522942 DOI: 10.1016/0197-4580(92)90037-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The 24-h growth hormone secretory pattern and GH response to growth hormone releasing hormone, the alpha 2-adrenoceptor agonist clonidine and the somatostatin-analogue SMS 201-995 were evaluated in 9 patients with Alzheimer's disease and 9 age- and body body-matched control subjects. The secretory profile did not differentiate between patients and controls. Both secreted the largest amount of GH during the early nighthours between 22.00-02.00, whereas the majority of daytime GH levels were below the assay's detection limit (0.4 ng/ml). No difference was found in GH response to GHRH between patients and controls. All subjects showed significantly enhanced GH secretion after GHRH. Dividing the patients into two groups according to age-of-onset (less than 60 years greater than), there was a trend toward larger GH responses to GHRH for the early-onset group. No other parameter differentiated the groups. GH levels after clonidine were blunted in all subjects but one AD patient, probably due to an age-dependent attenuation frequently observed in subjects over 45 years of age. Finally, the administration of the somatostatin-analogue did not render conclusive results, since spontaneous decline of GH concentration was already beginning 2 hours before the drug was given and continued steadily throughout the observation period. In conclusion, patients with only mild to moderate degree of Alzheimer's disease have no prominent changes in GH regulation.
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Affiliation(s)
- I J Heuser
- Experimental Therapeutics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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8
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Falkenstein BA, Holley DC. Effect of acute intravenous administration of delta-9-tetrahydrocannabinol on the episodic secretion of immunoassayable growth hormone in the rat. Life Sci 1992; 50:1109-16. [PMID: 1313519 DOI: 10.1016/0024-3205(92)90348-s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Blood samples from unrestrained, unanesthetized, male rats (300-350 g) were obtained every 15 min. for 9 consecutive hrs. (1000-1900 h). Each rat received, intravenously, a vehicle injection (controls) or a 2.0 mg/kg dose of delta-9-tetrahydrocannabinol (THC) at 1300 h to determine the effect of this drug on the spontaneous episodic secretion of plasma immunoassayable rat growth hormone (rGH). Acute administration of THC suppressed the secretion of rGH, as is evident from mean plasma level (p less than .01), peak height (p less than .02), and integrated peak amplitude (p less than .02) analyses. Episodic secretion was inhibited in all animals (n = 7) receiving THC. Although further investigation is needed to define clearly the physiological mechanisms involved in this response, these data indicate that THC can inhibit the hypothalamic-pituitary control of normal episodic growth hormone secretion in the rat.
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Affiliation(s)
- B A Falkenstein
- Department of Biological Sciences, San Jose State University, CA 95192
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9
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Jiménez-Jiménez FJ, Tabernero C, Mena MA, García de Yébenes J, García de Yébenes MJ, Casarejos MJ, Pardo B, García-Agundez JA, Benítez J, Martínez A. Acute effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in a model of rat designated a poor metabolizer of debrisoquine. J Neurochem 1991; 57:81-7. [PMID: 1711101 DOI: 10.1111/j.1471-4159.1991.tb02102.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The relationship between oxidative polymorphisms and the cause of Parkinson's disease is controversial. The drug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which induces parkinsonism in humans and in some animal models, is metabolized by cytochrome P450 db1 isozyme (the same enzymatic system implicated in 4-hydroxylation of debrisoquine). In this study, we treated females of three rat species, which differ in their ability to hydroxylate debrisoquine, with MPTP (three doses of 30 mg/kg s.c. at 12-h intervals), and we measured their motor activity and brain monoamine levels. Female dark-adapted rats (poor metabolizers of debrisoquine) showed a more pronounced and more maintained reduction of their motor activity after treatment with MPTP. MPTP-treated, dark-adapted rats also had a depletion of noradrenaline in the diencephalon and a depletion of dopamine and serotonine and their respective metabolites in the limbic system when compared with the other two species. These results suggest that oxidative polymorphism of debrisoquine plays a role in the acute effects of MPTP.
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10
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Abstract
In seven normal volunteers, the basal and arginine-stimulated levels of plasma growth hormone, glucose, glucagon, and free fatty acids and serum insulin was determined during placebo and during indomethacin 25 mg four times daily. Basal plasma growth hormone was higher during indomethacin (5.4 +/- 1 vs 1.7 +/- 2 ng/ml, p less than 0.005), as was the mean integrated response to intravenous arginine (40 +/- 14 vs 6 +/- 4 ng.min/ml, p less than 0.05). Despite lack of effect on plasma glucagon, indomethacin decreased the insulin response to arginine. The fall in free fatty acids during arginine infusion was decreased by indomethacin, which may in part be due to increased plasma growth hormone levels. In view of the many patients treated with indomethacin, the effect on growth hormone may be of clinical importance.
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Affiliation(s)
- J K Schmitt
- Department of Veterans Affairs Medical Center, Richmond, Virginia
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11
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Suri D, Hindmarsh PC, Brain CE, Pringle PJ, Brook CG. The interaction between clonidine and growth hormone releasing hormone in the stimulation of growth hormone secretion in man. Clin Endocrinol (Oxf) 1990; 33:399-406. [PMID: 2147600 DOI: 10.1111/j.1365-2265.1990.tb00505.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Six normal adult males were given clonidine and GHRH either separately, or in combination, in random order. The peak serum GH concentrations elicited by clonidine or GHRH were variable but one factor influencing the GH response to GHRH was the GH secretory status in the hour prior to the administration of the GHRH. Peak serum GH concentrations attained were significantly greater when serum GH concentrations were rising (mean 52.9 mU/l, SD 17.2) than if they were falling (mean 27.5 mU/l, SD 13.3) or unchanged/undetectable (mean 20.6 mU/l, SD 9.8) (one-way ANOVA, F = 8.77; P = 0.004). The GH response to clonidine was not influenced by the secretory status in the hour prior to administration of clonidine. Pretreatment with clonidine did not augment the peak serum GH response to GHRH but the direction of response was more predictable than when GHRH was administered separately or repeatedly. Prior treatment with GHRH(1-29)-NH2 led to a marked attenuation of the peak serum GH response to clonidine. These results suggest that the alpha-2 adrenergic agonists probably stimulate GH secretion through pathways other than just GHRH.
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Affiliation(s)
- D Suri
- Endocrine Unit, Middlesex Hospital, London, UK
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12
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Alba-Roth J, von Creytz C, Mehltretter G, Schopohl J, Müller OA, von Werder K. Interaction of L-dopa and GHRH on GH secretion in normal men. J Endocrinol Invest 1989; 12:783-7. [PMID: 2515218 DOI: 10.1007/bf03350059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
To determine how L-dopa stimulates GH secretion, we investigated its interaction with GHRH in vivo. Six normal men were studied on 4 occasions: 1) L-dopa-TRH: 500 mg L-dopa orally followed by 200 micrograms TRH 60 min later; 2) L-dopa-GHRH-TRH: 100 micrograms GHRH 1-44 iv 30 min after L-dopa followed by 200 micrograms TRH iv; 3) GHRH-TRH: 100 micrograms GHRH iv at 0 min, 30 min later 200 micrograms TRH iv; 4) TRH test: 200 micrograms TRH iv as a bolus. After L-dopa-TRH GH-levels increased significantly from 0.6 micrograms/l to 25.8 +/- 9.6 (SE) micrograms/l at 60 min. Only a slight TSH and no PRL increase was observed after L-dopa-TRH. After L-dopa-GHRH-TRH the GH-increase was significantly higher (45.7 +/- 11.1 micrograms/l) compared to L-dopa-TRH alone. GHRH-TRH increased GH-levels to 52.5 +/- 12.1 micrograms/l, which was not significantly different from the GH-levels obtained when L-dopa-GHRH-TRH were given. TRH increased serum TSH and PRL to 6.3 +/- 0.7 microU/ml and 715 +/- 136 microU/ml, respectively, which was significantly higher compared to the TSH responses after L-dopa-TRH. The PRL and TSH increase after TRH only was also higher (TSH-max: 5.7 +/- 0.5 microU/ml; PRL-max: 899 +/- 154 microU/ml) compared to the TSH and PRL responses after L-dopa-TRH. Our results show that the combination of L-dopa with GHRH leads to the same GH response as GHRH only. However, both responses are significantly higher than the one after L-dopa alone.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Alba-Roth
- Medizinische Klinik Innenstadt, University of Munich, Federal Republic of Germany
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13
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Lewis BM, Dieguez C, Ham J, Page MD, Creagh FM, Peters JR, Scanlon MF. Effects of Glucose on Thyrotrophin-Releasing Hormone, Growth Hormone-Releasing Hormone, Somatostatin and Luteinizing Hormone-Releasing Hormone Release from Rat Hypothalamus in vitro. J Neuroendocrinol 1989; 1:437-41. [PMID: 19210414 DOI: 10.1111/j.1365-2826.1989.tb00144.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Abstract Increasing concentrations of D-glucose (1 to 25 mM) inhibited somatostatin, thyrotrophin-releasing hormone (TRH) and growth hormone-releasing hormone (GHRH) release from incubated adult rat hypothalami in a stereospecific manner. In contrast, the effects of D- and L-glucose on luteinizing hormone-releasing hormone release were virtually identical. Increasing concentrations of D-glucose also inhibited somatostatin release following depolarization with high K(+), but had no obvious effect on depolarization-induced TRH or GHRH release when compared with L-glucose. In conclusion, D-glucose exerts a potent, dose-related modulatory action on the release of rat hypothalamic TRH and GHRH as well as somatostatin in vitro. Further studies are required to establish any physiological relevance of glucose in the modulation of these hypothalamic neuropeptides.
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Affiliation(s)
- B M Lewis
- Neuroendocrine Unit, Department of Medicine, University of Wales College of Medicine, Cardiff, UK and Departmento de Fisiologia, Facultad de Medicina, Santiago de Compostela, Spain
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14
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Valcavi R, Dieguez C, Page MD, Zini M, Casoli P, Portioli I, Scanlon MF. Alpha-2-adrenergic pathways release growth hormone via a non-GRF-dependent mechanism in normal human subjects. Clin Endocrinol (Oxf) 1988; 29:309-16. [PMID: 2855221 DOI: 10.1111/j.1365-2265.1988.tb01229.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Administration of a supramaximal dose of GRF 1-44 (200 micrograms, i.v.) to normal human volunteers increased GH levels while a further bolus of GRF (200 micrograms i.v.) given 2 hours later failed to increase plasma GH levels. In contrast, alpha-adrenergic receptor agonism with either propranolol-adrenaline infusion or clonidine increased plasma GH levels at a time when GH responses to this supramaximal dose of GRF were absent. This indicates that alpha-adrenergic pathways stimulate GH secretion through a non-GRF-dependent mechanism in normal human subjects.
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Affiliation(s)
- R Valcavi
- 2a Divisione di Medicina Generale, Arcispedale, S. Maria Nuova, Reggio Emilia, Italy
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15
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Page MD, Dieguez C, Valcavi R, Edwards C, Hall R, Scanlon MF. Growth hormone (GH) responses to arginine and L-dopa alone and after GHRH pretreatment. Clin Endocrinol (Oxf) 1988; 28:551-8. [PMID: 3145820 DOI: 10.1111/j.1365-2265.1988.tb03690.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In order to investigate the mechanisms by which arginine and L-dopa cause GH release in humans we measured the GH response to GHRH 1-44 (200 micrograms i.v.), arginine (30 g i.v. over 30 min) and L-dopa (500 mg orally) administered alone and 120 minutes following pretreatment with GHRH 1-44 (200 micrograms i.v.) in normal male subjects. Prior GHRH administration abolished the GH response to subsequent GHRH. Arginine infusion induced a rise in GH levels maximal at 45 min. Following GHRH pretreatment the GH response to arginine was enhanced, with peak values of 19.3 +/- 6.4 vs 53.3 +/- 16.5 mU/l (mean +/- SEM) respectively (P less than 0.02). L-dopa alone induced a rise in GH levels maximal at 90 min (17.6 +/- 7.4 mU/l, mean +/- SEM) but this rise was abolished by pretreatment with GHRH.
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Affiliation(s)
- M D Page
- Department of Medicine, University of Wales College of Medicine, Health Park, Cardiff, UK
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16
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Affiliation(s)
- C Dieguez
- Department of Medicine, University of Wales College of Medicine, Heath Park, Cardiff, UK
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17
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Delitala G, Tomasi P, Virdis R. Prolactin, growth hormone and thyrotropin-thyroid hormone secretion during stress states in man. BAILLIERE'S CLINICAL ENDOCRINOLOGY AND METABOLISM 1987; 1:391-414. [PMID: 3327498 DOI: 10.1016/s0950-351x(87)80069-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Changes in hormone secretion and/or metabolism almost constantly accompany stressful events. The hormonal response to stress is directly related to the intensity of the stimulus, and greatly depends on the individual's perception of potentially stressful situations. Hypoglycaemia, surgery and exercise represent physical, metabolic and psychological stressful events where the activation of the endocrine system plays a great role. These endocrine responses also include the secretion of GH and prolactin, but the response pattern varies with the stimulus. Hypoglycaemia, exercise and surgery are potent stimuli to GH and prolactin release, both in men and women. The available data suggest that prolactin is more responsive than GH to surgical stress, whereas physical exercise and hypoglycaemia preferentially stimulate GH secretion. Prolactin levels during hypoglycaemia rise solely when symptomatic neuroglycopenia is achieved. By contrast, prolactin and GH responses to purely psychological stress are rarely seen, although some forms of reproductive stress may potentiate prolactin release in women. A teleologically satisfactory rationale for the acute GH and prolactin rise in response to these stressful stimuli is not clearly apparent in man. No definite metabolic activity of prolactin on intermediate metabolism has been demonstrated, although prolactin is mildly diabetogenic. The known metabolic actions of GH do not appear to be critical during surgery or acute hypoglycaemia, although GH probably participates in the regulation of metabolic homeostasis during chronic hypoglycaemia and chronic exercise. Changes in secretion and/or metabolism of hypothalamic neurotransmitters can increase the secretion of GH by increasing the secretion of GHRH or by decreasing the secretion of somatostatin. The prolactin rise is brought about by either a decrease in dopamine activity, an increased secretion of a hypothetical PRF, or by both mechanisms. Since multiple neuronal pathways converge on the hypothalamus from many other parts of the brain, the pronounced effects of hypoglycaemia, exercise and surgery on the secretion of GH and prolactin also reflect the action of different and complex neural inputs on the activity of the hypothalamic-pituitary axis. However, the morpho-functional mapping of these excitatory pathways still remains incomplete. TSH secretion is tightly regulated by the negative feed-back mechanism exerted by thyroid hormones. The small changes in TSH level observed during surgery and physical exercise seem to reflect mainly alterations in peripheral T4 metabolism.(ABSTRACT TRUNCATED AT 400 WORDS)
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18
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Page MD, Koppeschaar HP, Edwards CA, Dieguez C, Scanlon MF. Additive effects of growth hormone releasing factor and insulin hypoglycaemia on growth hormone release in man. Clin Endocrinol (Oxf) 1987; 26:589-95. [PMID: 3117447 DOI: 10.1111/j.1365-2265.1987.tb00814.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have measured GH and PRL changes following separate and combined administration of insulin and GH releasing factor (GRF) in six normal males. Peak GH responses to separate administration of insulin and GRF were comparable (71.4 +/- 10.2 vs 70.1 +/- 27.7 mU/l; mean +/- SEM). However, the peak GH response following combined administration was significantly higher (120.8 +/- 29.7, P less than 0.05) as was the total GH released as calculated by measuring the area under the curve (P less than 0.05). In contrast the PRL response to hypoglycaemia was not altered by the combined administration of insulin and GRF. This effect was not due to any direct action of hypoglycaemia or insulin at pituitary level since basal and 10(-8) M GRF stimulated GH release from rat anterior pituitary cells in vitro was not influenced by varying glucose and insulin levels. Our findings support the hypothesis that GRF and insulin-induced hypoglycaemia release GH via different pathways which are, at least in part, additive.
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Affiliation(s)
- M D Page
- Department of Medicine, University of Wales College of Medicine, Heath Park, Cardiff
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19
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Wass JA, Laws ER, Randall RV, Sheline GE. The treatment of acromegaly. CLINICS IN ENDOCRINOLOGY AND METABOLISM 1986; 15:683-707. [PMID: 2876792 DOI: 10.1016/s0300-595x(86)80015-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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20
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Bercu BB, Diamond FB. Growth hormone neurosecretory dysfunction. CLINICS IN ENDOCRINOLOGY AND METABOLISM 1986; 15:537-90. [PMID: 2429794 DOI: 10.1016/s0300-595x(86)80010-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The basis for understanding clinical disorders in the neuroregulation of GH secretion is derived from the complexity of the CNS-hypothalamic-pituitary axis. Studies in animals and humans demonstrate an anatomic, physiological and pharmacological evidence for neurosecretory control over GH secretion including neurohormones (GRH, somatostatin), neurotransmitters (dopaminergic, adrenergic, cholinergic, serotonergic, histaminergic, GABAergic), and neuropeptides (gut hormones, opioids, CRH, TRH, etc). The observation of a defect in the neuroregulatory control of GH secretion in CNS-irradiated humans and animals led to the hypothesis of a disorder in neurosecretion, GHND, as a cause for short stature. We speculate that in this heterogeneous group of children a disruption in the neurotransmitter-neurohormonal functional pathway could modify secretion ultimately expressed as poor growth velocity and short stature.
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21
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Bovine Somatotropin: Physiology, Lactational Responses and Implications for the Dairy Industry1. ACTA ACUST UNITED AC 1986. [DOI: 10.15232/s1080-7446(15)32418-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Sopwith AM, Penny ES, Grossman A, Savage MO, Besser GM, Rees LH. Normal circulating immunoreactive growth hormone releasing factor (hGRF) concentrations in patients with functional hypothalamic hGRF deficiency. Clin Endocrinol (Oxf) 1986; 24:395-400. [PMID: 2874905 DOI: 10.1111/j.1365-2265.1986.tb01643.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Using a highly specific radioimmunoassay we have measured the concentrations of human growth hormone releasing factor (ir-hGRF) in the peripheral circulation of six individuals with acquired hypothalamic hGRF deficiency. Despite their hypothalamic dysfunction venous plasma ir-hGRF increased normally in every patient after the stimulus of a mixed breakfast, from an average concentration basally of 13.6 +/- 6.0 pg/ml to a maximum of 29.0 +/- 8.4 pg/ml (mean +/- SEM) at 120 min. The findings indicate that circulating hGRF is at least in large part extrahypothalamic in origin, which in turn implies a physiological role for hGRF in the periphery.
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Hall TR, Cheung A, Harvey S, Lam SK, Spencer GS. Somatostatin immunoneutralization affects plasma metabolite concentrations in the domestic fowl. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. A, COMPARATIVE PHYSIOLOGY 1986; 85:489-94. [PMID: 2878778 DOI: 10.1016/0300-9629(86)90435-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Young leghorn cockerels were injected with antiserum to somatostatin (anti-SRIF) and plasma glucose, free fatty acids and alpha-amino nitrogen concentrations determined. Plasma glucose concentrations increased rapidly after anti-SRIF and remained high for up to 2 hr. Two different antisera tested had hyperglycaemic activity. Plasma free fatty acids also increased rapidly after administration of the two different anti-SRIFs, and remained high for about 1 hr. Plasma alpha-amino nitrogen increased during the first 30 min after anti-SRIF, then declined to levels significantly lower than control by 1-2 hr after injection. Anaesthesia reduced plasma concentrations of glucose and alpha-amino nitrogen, and also reduced the changes of these metabolites following anti-SRIF. The results show the importance of endogenous somatostatin in the regulation of plasma metabolite concentrations.
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