EFFECT OF l-DOPA ADMINISTRATION ON GROWTH HORMONE SECRETION IN NORMAL SUBJECTS AND PARKINSONIAN PATIENTS

SUMMARY The effect of both oral and intravenous administration of l-DOPA on growth hormone (GH) secretion was studied in a group of normal volunteers: a significant rise of serum GH levels was observed in both cases. Growth hormone release in response to insulin hypoglycaemia and to arginine infusion was evaluated in a group of Parkinsonian patients before and after 25 days' treatment with l-DOPA plus a DOPA-decarboxylase inhibitor. In addition, GH response to the above stimuli was studied in a group of patients who had been under treatment for more than 6 months with l-DOPA alone. In untreated Parkinsonian patients, GH response to insulin hypoglycaemia was at the lower limit of normal range while arginine-induced GH release was significantly reduced. Treatment with l-DOPA did not increase GH responses. Some possible interpretations of the results are discussed. The findings support the possibility that dopamine plays a role in the physiological regulation of GH secretion, as in the case of luteinizing hormone, follicle-stimulating hormone and prolactin release.

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EFFECT OF AMINOPHYLLINE ON GROWTH HORMONE SECRETION IN MAN

Acta Endocrinologica ◽

10.1530/acta.0.0760488 ◽

1974 ◽

Vol 76 (3) ◽

pp. 488-494 ◽

Cited By ~ 1

Author(s):

M. Peracchi ◽

F. Cavagnini ◽

A. E. Pontiroli ◽

U. Raggi ◽

A. Malinverni ◽

...

Keyword(s):

Growth Hormone ◽

Blood Glucose ◽

Intravenous Infusion ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Normal Subjects ◽

Gh Secretion ◽

Inhibiting Effect ◽

Plasma Ffa ◽

Serum Gh

ABSTRACT The effects of intravenously administered aminophylline on growth hormone (GH) secretion have been studied in sixteen normal subjects and four acromegalic patients. Intravenous infusion of theophylline ethylenediamine 480 mg over a 30 min period did not alter the blood glucose and serum GH levels in six normal subjects but raised the plasma FFA by 88 %. By contrast, in four acromegalic patients theophylline administration resulted in a fall of the serum GH levels by 17.6–51.7 %, mean 36.5%. In ten normal subjects the infusion of the drug clearly blunted the GH response to insulin hypoglycaemia without modifying the decrease in blood glucose and plasma FFA induced by insulin: mean peak GH values decreased from 32.7 ± 3.39 to 21.4 ± 4.10 ng/ml (P < 0.025). These data seem to indicate that theophylline has an overall inhibiting effect on the hypothalamic-hypophyseal axis for GH secretion.

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Galanin does not affect the growth hormone-releasing hormone-stimulated growth hormone secretion in patients with hyperthyroidism

Acta Endocrinologica ◽

10.1530/acta.0.1270504 ◽

1992 ◽

Vol 127 (6) ◽

pp. 504-508 ◽

Cited By ~ 9

Author(s):

Andrea Giustina ◽

Anna Rosa Bussi ◽

Fabio Legati ◽

Simonetta Bossoni ◽

Massimo Licini ◽

...

Keyword(s):

Growth Hormone ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Random Order ◽

Normal Subjects ◽

Graves Disease ◽

Growth Hormone Releasing Hormone ◽

Gh Secretion ◽

Hyperthyroid Patients ◽

Secretory Capacity

Patients with hyperthyroidism have reduced spontaneous and stimulated growth hormone (GH) secretion. The aim of our study was to evaluate the effects of galanin, a novel neuropeptide which stimulates GH secretion in man, on the GH response to GHRH in patients with hyperthyroidism. Eight untreated hyperthyroid patients with Graves' disease (6F, 2M, aged 25–50 years) and six healthy volunteers (3F, 3M, aged 27–76 years) underwent from - 10 to 30 min in random order: (i) porcine galanin, iv, 500 μg in 100 ml saline; or (ii) saline, iv, 100 ml. A bolus of human GHRH(1-29)NH2, 100 μg, was injected iv at 0 min. Hyperthyroid patients showed blunted GH peaks after GHRH+saline (10.2±2.5 μg/l) compared to normal subjects (20.7±4.8 μg/l, p< 0.05). GH peaks after GHRH+ galanin were also significantly lower in hyperthyroid subjects (12.5±3 μg/l) compared to normal subjects (43.8±6 μg/l, p<0.05). That galanin is not able to reverse the blunted GH response to GHRH in hyperthyroidism suggests that hyperthyroxinemia may either increase the somatostatin release by the hypothalamus or directly affect the pituitary GH secretory capacity.

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Effect of exogenous growth hormone administration on endogenous growth hormone secretion induced by a met-enkephalin analog

Acta Endocrinologica ◽

10.1530/eje.0.1340073 ◽

1996 ◽

Vol 134 (1) ◽

pp. 73-76 ◽

Cited By ~ 2

Author(s):

Giuseppe Fanciulli ◽

Osvaldo Oliva ◽

Paolo A Tomasi ◽

Alessandra Pala ◽

Alba Bertoncelli ◽

...

Keyword(s):

Growth Hormone ◽

Endogenous Growth ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Inhibitory Effect ◽

Growth Hormone Administration ◽

Gh Secretion ◽

Hormone Administration ◽

Exogenous Growth ◽

Serum Gh

Fanciulli G, Oliva O, Tomasi PA. Pala A. Bertoncelli A, Dettori A, Delitala G. Effect of exogenous growth hormone administration on endogenous growth hormone secretion induced by a met-enkephalin analog. Eur J Endocrinol 1996:134:73–6. ISSN 0804–4643 Exogenous growth hormone (hGH) administration in humans attenuates the endogenous growth hormone (GH) response to some pharmacological stimuli: in particular, pretreatment with hGH completely blocks the serum GH response to growth hormone-releasing hormone. In order to evaluate the mechanism(s) whereby opioids induce GH secretion in man, we gave the following treatments to six healthy male volunteers: (a) IV saline: (b) a met-enkephalin analog G-DAMME 250 μg IV as a bolus at time ′: (c) hGH 2 IU as an IV bolus at time −180′; (d) G-DAMME as above, preceded by hGH as above. In our study. G-DAMME stimulated GH secretion both basally (peak 17.9 ± 6.0 ng/ml) and, to a lesser extent, after hGH pretreatment (6.0 ± 2.7 ng/ml). Since in our study G-DAMME was able to partially overcome the inhibitory effect of hGH administration, it is suggested that opioids act through an inhibition of somatostatin release and not through a GHRH-dependent pathway. However, an additional direct effect of hGH on pituitary somatotrophes cannot be excluded. Giuseppe Delitala, Chair of Endocrinology, Viale S. Pietro 12, University of Sassari, 07100 Sassari. Italy

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Influence of chronic naltrexone treatment on growth hormone secretion in normal subjects

Acta Endocrinologica ◽

10.1530/eje.0.1370631 ◽

1997 ◽

pp. 631-634 ◽

Cited By ~ 5

Author(s):

P Villa ◽

D Valle ◽

L De Marinis ◽

A Mancini ◽

A Bianchi ◽

...

Keyword(s):

Hormone Secretion ◽

Growth Hormone Secretion ◽

Normal Subjects ◽

Molar Ratio ◽

Normal Female ◽

Gh Secretion ◽

Igf I ◽

Before And After ◽

Ghrh Test ◽

Igfbp 3

OBJECTIVE: To verify if a chronic opioid blockade could affect the GH/IGF-I axis. DESIGN: We have investigated the effects of naltrexone (NTX) treatment on GH response to GHRH in normal women. METHODS: GHRH test (50 micrograms i.v.) performed in seven normal female volunteers (age 25-38 years, with a body mass index ranging from 19.8 to 23.1 kg/m2) before and after 4-weeks NTX treatment (50 mg p.o. daily). RESULTS: Basal GH, IGF-I, insulin-like growth factor binding protein-3 (IGFBP-3) plasma levels and the IGF-I/IGFBP-3 molar ratio remained unaffected by NTX. NTX significantly reduced the GH peak values (15.52 +/- 3.59 vs 4.78 +/- 0.49 micrograms/l; P < 0.01), and GH area under curve (918.93 +/- 253.96 vs 401.09 +/- 79.63 micrograms/l; P < 0.01). CONCLUSIONS: This finding suggests that the long-term opioid receptor blockade has an inhibitory role on GHRH-induced GH secretion. A central influence on neurotransmitter control of GH might be hypothesised. The inhibition of stimulated GH release, without interference with the basal level, could indicate an enhanced somatostatin secretion and/or activity. Opioids could be involved only in the regulation of GH dynamics and not in basal secretion. Nevertheless, a direct involvement of opioids at the pituitary level, which could be modified by NTX, cannot be excluded.

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Effects of repetitive administration of growth hormone-releasing hormone on growth hormone secretion, insulin-like growth factor I, and bone metabolism in postmenopausal women

Acta Endocrinologica ◽

10.1530/acta.0.1200121 ◽

1989 ◽

Vol 120 (1) ◽

pp. 121-128 ◽

Cited By ~ 33

Author(s):

Paul Franchimont ◽

Didier Urbain-Choffray ◽

Pierre Lambelin ◽

Marie-Anne Fontaine ◽

Gerard Frangin ◽

...

Keyword(s):

Growth Hormone ◽

Bone Metabolism ◽

Postmenopausal Women ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Significant Rise ◽

Maximum Peak ◽

Gh Secretion ◽

Age Related ◽

Igf I

Abstract. This study sought to determine whether GH response to synthetic GHRH was impaired in 13 postmenopausal (55-71 years) as compared with that in 8 eugonadal women and whether IGF-I and bone metabolism were consequently depressed. Thereafter, the effects of daily iv injections of 80 μg GHRH-44 for 8 days were studied in the same postmenopausal group. In addition to significantly higher basal IGF-I and osteocalcin levels (P< 0.005) in eugonadal as compared with the postmenopausal women, the administration of one GHRH-44 injection resulted in significantly higher 120-min postinjection GH maximum peak and cumulative responses in the former group as well (P< 0.005). Highly significant correlations were observed between 17β-estradiol plasma levels and either GH maximum peak or cumulative responses to GHRH-44 when both groups were pooled together, but not when considered independently. In postmenopausal women, a correlation was found between both age and duration of menopause and GH responses. Repeated GHRH-44 injections in postmenopausal women induced a significant increase in GH response (P< 0.001) as well as in IGF-I levels from day 4 to 8. No phospho-calcium parameters were modified except for a significant rise in osteocalcin from day 2 to 8. These data indicate an age-related loss of sensitivity of somatotrope cells to GHRH-44 in postmenopausal women, partly corrected by repeated daily GHRH-44 injections. As a consequence of the GHRH-induced increase in GH secretion, IGF-I was also enhanced and may be responsible for a stimulatory effect on bone formation, as shown by the osteocalcin increase, uncoupled from bone resorption.

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Intravenous administration of ghrelin stimulates growth hormone secretion in vagotomized patients as well as normal subjects

Acta Endocrinologica ◽

10.1530/eje.0.1510447 ◽

2004 ◽

pp. 447-450 ◽

Cited By ~ 19

Author(s):

R Takeno ◽

Y Okimura ◽

G Iguchi ◽

M Kishimoto ◽

T Kudo ◽

...

Keyword(s):

Growth Hormone ◽

Direct Action ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Normal Subjects ◽

Vagal Nerve ◽

Gh Secretion ◽

Afferent Vagal ◽

Vagal Afferent ◽

Plasma Gh

OBJECTIVE: Ghrelin is a potent peptide stimulating GH secretion. Besides its direct action on the pituitary, ghrelin has been reported to stimulate GH release via the vagal afferent nerve in rats. To examine the involvement of vagal nerve in ghrelin-induced GH secretion in humans, GH responses to ghrelin were compared between vagotomized patients with gastrectomy and normal subjects. METHODS: Ghrelin (0.2 microg/kg) or GHRH (1 microg/kg) was administered intravenously in vagotomized patients and normal subjects on separate days, and plasma GH responses to the stimuli were examined. RESULTS: Ghrelin caused a significant plasma GH rise in both vagotomized patients and normal subjects. Peak GH levels in vagotomized patients (37.5+/-16.9 ng/ml) were not different from those in normal subjects (29.9+/-23.1 ng/ml). The areas under the curve of GH response to ghrelin did not differ between the two groups. GHRH also increased GH levels, and peak GH levels and areas under the curve after GHRH stimulation were also comparable between vagotomized patients and normal subjects. CONCLUSIONS: In the present study, the involvement of the afferent vagal nerve in ghrelin-induced GH secretion was not confirmed in humans.

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EFFECT OF ANDROGEN ON GROWTH HORMONE SECRETION AND GROWTH IN BOYS WITH SHORT STATURE

Acta Endocrinologica ◽

10.1530/acta.0.0910201 ◽

1979 ◽

Vol 91 (2) ◽

pp. 201-212 ◽

Cited By ~ 40

Author(s):

Luis G. Martin ◽

Milton S. Grossman ◽

Thomas B. Connor ◽

Lynn L. Levitsky ◽

John W. Clark ◽

...

Keyword(s):

Growth Hormone ◽

Short Stature ◽

Sexual Maturation ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Growth Potential ◽

Hormone Deficiency ◽

Arginine Infusion ◽

Young Males ◽

Before And After

ABSTRACT The response of plasma growth hormone (GH) to insulin-induced hypoglycaemia (IIH) and arginine infusion (AI) was studied in 22 young males (ages 8 to 17 years) with short stature and absent or delayed sexual maturation, before and after androgen administration. During initial evaluation, 5 patients had blunted GH response to IIH, 12 responded subnormally to AI and 4 failed to respond normally to either stimulus. These same studies were repeated in each patient following androgen administration. The source of androgen was as follows: a) 5 days of testosterone propionate (25 mg intramuscularly daily) in 20 patients. b) Methyltestosterone, 10 mg t. i. d. orally for four days in the other 2 subjects. In almost every case, androgen administration resulted in raising the levels of fasting GH and enhancement of the GH responses to IIH and AI was observed. Patients manifesting subnormal GH responses to these stimuli before androgen consistently demonstrated a normal response when challenged with identical stimuli during androgen administration. Growth velocities during the year following these studies were significantly increased in most instances and the growth spurts correlated well with the progression of sexual maturation. Sustained improvement in the GH responses to IIH and AI were uniformly observed in 3 patients when repetitive studies were performed 8 to 12 months later during spontaneous advancing sexual development. The results indicate that brief androgen administration can be helpful in delineating the cause of growth retardation in boys with short stature and delayed sexual maturation, particularly when the diagnosis of isolated growth hormone deficiency is suspected. They also offer prognostic value in determining growth potential in this same group of young males.

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Effects of cytidine 5'-diphosphocholine administration on basal and growth hormone-releasing hormone-induced growth hormone secretion in elderly subjects

Acta Endocrinologica ◽

10.1530/acta.0.1240516 ◽

1991 ◽

Vol 124 (5) ◽

pp. 516-520 ◽

Cited By ~ 7

Author(s):

Gian Paolo Ceda ◽

Graziano Ceresini ◽

Licia Denti ◽

Dario Magnani ◽

Lorenzo Marchini ◽

...

Keyword(s):

Growth Hormone ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

The Elderly ◽

Treated Group ◽

Elderly Subjects ◽

Releasing Hormone ◽

Gh Secretion ◽

Healthy Elderly ◽

Serum Gh

Abstract. The basal and GH-releasing hormone-stimulated secretion of GH declines in the elderly. We tested the ability of cytidine 5'-diphosphocholine, a drug used in the treatment of stroke and Parkinson's disease, to alter GH secretion in 11 healthy elderly volunteers, aged 69-84. Each subject received an iv infusion of 2 g of cytidine 5'-diphosphocholine or normal saline. GHRH and TRH were also administered during cytidine 5'diphosphocholine infusions. The infusion of cytidine 5'-diphosphocholine induced a 4-fold (p<0.05) increase in serum GH levels over basal values. A small increase in GH was seen after GHRH administration. However, the addition of GHRH to the cytidine 5'-diphosphocholine infusion resulted in a GH response which was significantly greater than that seen after GHRH alone; the integrated concentration of GH was more than 2-fold greater in the cytidine 5'-diphosphocholine treated group (706.85± 185.1 vs 248.9±61.4 μg · l−1 · (120 min)−1; p=0.01). The PRL and TSH responses to TRH were not significantly affected by cytidine 5'-diphosphocholine infusion, indicating that dopaminergic mechanisms are not involved. These studies demonstrate that cytidine 5'-diphosphocholine can enhance basal and GHRH-stimulated GH release in the elderly, but the mechanism of action of the drug remains unclear.

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Role of GH in regulating nocturnal rates of lipolysis and plasma mevalonate levels in normal and diabetic humans

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1992.263.1.e168 ◽

1992 ◽

Vol 263 (1) ◽

pp. E168-E172 ◽

Cited By ~ 4

Author(s):

P. J. Boyle ◽

A. Avogaro ◽

L. Smith ◽

D. M. Bier ◽

A. S. Pappu ◽

...

Keyword(s):

Growth Hormone ◽

Fatty Acid ◽

Cholesterol Synthesis ◽

Gh Deficiency ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Normal Subjects ◽

Nonesterified Fatty Acid ◽

Rate Limiting Step ◽

Nocturnal Increase

To define the role that nocturnal increments in growth hormone (GH) play in maintaining lipolysis, glycerol turnover was measured in six patients with GH deficiency and six normal subjects during sleep. Glycerol production initially decreased in both groups but then increased to 1.44 +/- 0.20 mumol.kg-1.min-1 by 0800 h in normal subjects, whereas GH deficiency was associated with a continuous fall to 0.77 +/- 0.10 mumol.kg-1.min-1, P less than 0.02. Nonesterified fatty acid levels paralleled these changes. Six GH-deficient patients received basal GH replacement including a pulse during sleep, which resulted in normal fasting fatty acid levels (P less than 0.05, replaced vs. chronic deficiency). To assess a possible link between the normal nocturnal increase in plasma mevalonate (the product of the rate-limiting step in cholesterol synthesis) and sleep-associated GH release, 11 GH-deficient patients and 11 normal subjects were studied. Peak nocturnal and fasting mevalonate concentrations were not correlated with GH level. We conclude that nocturnal growth hormone secretion is essential for maintaining lipolysis but that it is not related to normal increments in mevalonate and, by inference, to cholesterol synthesis during sleep

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