Effect of L-Tryptophan on Growth Hormone and Prolactin Release in Normal Volunteers and Patients with Secretory Pituitary Tumors

Fraser, Warren M.; Tucker, Henry; Grubb, Stephen R.; Wigand, James P.; Blackard, William G.

doi:10.1055/s-0028-1092698

Cited by 26 publications

(4 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, a stimulatory role of 5-HT on cGH release has also been suggested, based on the finding that activation of 5-HT neurotransmission with 5-hydroxytryptophan (5-HTP) increases plasma GH levels [31]. Finally, as happened with dogs, based on data obtained in humans, stimulatory, inhibitory or no influence of serotoninergic pathways have been claimed [3, 4, 5, 7, 9, 10, 11]. However, in light of the poor specificity of most of the drugs used in these studies, it was concluded by most authors that no firm conclusions could be reached [1, 2].…”

Section: Discussionmentioning

confidence: 99%

“…Although in the last two decades considerable insight has been gained with regard to the role played by different neurotransmitter pathways, the mechanisms underlying the serotoninergic control of GH secretion are not yet clear, with stimulatory, inhibitory or no effect having been reported [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]. This limitation has mainly been due to the existence of many different receptors that mediate the serotonin (5-HT) actions, and the lack of suitable specific agonist and antagonist drugs.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Different Serotonin Receptor Subtypes On Growth Hormone Secretion

Valverde

Peñalva²,

Diéguez

2000

Neuroendocrinology

View full text Add to dashboard Cite

The role of serotonin (5-HT) in the regulation of growth hormone (GH) secretion remains unclear due to the existence of many different receptors that mediate the 5-HT actions, and the lack of suitable specific agonist and antagonist drugs. In the present work we have taken advantage of the recent development of new selective 5-HT drugs in order to clarify the role played by different 5-HT receptor types and subtypes on GH secretion. The experiments were carried out on beagle dogs. GH-releasing hormone (GHRH) increased basal canine GH (cGH) levels from 0.8 ± 0.2 to 8.8 ± 1.7 µg/l at 15 min. Administration of 5-HT_1D receptor agonist sumatriptan (SUM) induced a cGH peak at 30 min of 12.9 ± 2.7 µg/l. The combined administration of GHRH plus SUM strikingly potentiated cGH release with a peak of 36.9 ± 6 µg/l at 30 min (p < 0.05). Pretreatment with the muscarinic receptor antagonist atropine completely abolished the cGH response to SUM, while the cholinergic agonist pyridostigmine (PYR) did not modify this response (15.3 ± 5 µg/l PYR plus SUM vs. SUM alone 12.9 ± 2.7 µg/l). On the other hand, administration of drugs with activity at 5-HT_2A/C receptors showed a stimulatory role for the 5-HT_2C receptor subtype, since LY-53857 (antagonist 5-HT_2A/C) and DOI agonist (5-HT_2A/C) both modified the GH response stimulated by GHRH (AUC 88.5 ± 30.4 and 400 ± 64.6 vs. 267.3 ± 52.6 respectively), while ketanserin (antagonist 5-HT_2A) did not modify this response. The 5-HT₃ antagonist ICS-205–930 failed to modify either basal or GHRH induced GH responses. In conclusion, our data show that 5-HT_1D receptors play a stimulatory role on GH secretion in the dog, possibly by acting through a decrease in hypothalamic somatostatin release. Similarly, the 5-HT_2C receptor subtypes also appear to play a stimulatory role. However, 5-HT_2A and 5-HT₃ receptors do not appear to be involved in the control of basal and GHRH-induced GH secretion.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Different Serotonin Receptor Subtypes On Growth Hormone Secretion

Valverde

Peñalva²,

Diéguez

2000

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…Although results have been variable, the present study agrees with the consensus that tryptophan has little or no effect on GH secretion in humans. Thus, Woolf and Lee (1977) and Koulu and Lammintausta (1979) found a srnall but significant increase in plasma GH after tryptophan was given to men, while Müller et aL (1974) and Fraser et al (1979) found a significant GH response in women but not in men. Tryptophan has been reported to blunt the GH response to insulin hypoglycemia in humans (Müller et al, 1974), but this.finding was not confirmed (Woolf and Lee, 1977).…”

Section: Discussionmentioning

confidence: 98%

Effect of L-Tryptophan on Apomorphine-Induced Growth Hormone Secretion in Normal Subjects

Lal¹,

Young²,

Cervantes³

et al. 1980

Pharmacopsychiatry

View full text Add to dashboard Cite

Oral administration of the serotonin precursor, L-tryptophan, to normal male volunteers (n = 7) in a dose (3 g) sufficient to increase free plasma tryptophan concentrations more than 12-fold had no significant effect on basal growth hormone secretion or on apomorphine HCL-induced (0.75 mg sc) peak growth hormone concentrations. These data suggest that, in man, tryptophan administration has little effect on central dopaminergic function, at least in the hypothalamic-pituitary axis and that serotonergic mechanisms have no major modulatory effect on dopamine-mediated growth hormone secretion.

show abstract

“…Our findings of decreased and postponed response of GH to glucagon after the administration of the serotonin antagonist cyproheptadine confirms the role of serotoninergic receptors in the GH release. A blunted rise of GH in response to hypoglycemia (Bivens, Lebovitz and Feldman 1973), sleeping (Dammacco et al 1977), 1-tryptophan (Fraser, Tucker, Grubb, Wigaud and Blackard 1979), 1-DOPA (Nakai and Imura 1975) and to physical exercise (Smythe and Lazarus 1974) has been reported after cyproheptadine pretreatment. On the contrary, another serotonin antagonist, methysergide, has been shown to be in-…”

Section: Discussionmentioning

confidence: 99%

The Effect of TRH, Cyproheptadine and Pimozide on the Growth Hormone Response to Intramuscular Glucagon

Hainer¹,

Urbánek²,

Malec³

et al. 1981

Horm Metab Res

View full text Add to dashboard Cite

Glucagon-induced growth hormone (GH) secretion was studied in healthy subjects under basal conditions (n = 18), and when treated with TRH (n = 10), cyproheptadine (n = 8) and pimozide (n = 6). With glucagon alone, the mean serum GH level significantly increased at 150 minutes and at 180 minutes. TRH administered as a bolus injection completely suppressed the GH response to glucagon. Cyproheptadine pretreatment resulted in a substantial suppression of the GH response to glucagon. A significant difference between basal and post-cyproheptadine GH levels was observed at 150 minutes after glucagon. Pimozide pretreatment was followed by a reduction of GH response to glucagon, but the difference between control and pimozide-treated groups was not significant. In conclusion, it is proposed that glucagon-induced GH secretion is at least partly mediated via serotoninergic mechanisms while significant dopaminergic involvement does not seem probable. It is further suggested that TRH plays a substantial inhibitory role in glucagon-stimulated SH secretion.

show abstract

Effect of L-Tryptophan on Growth Hormone and Prolactin Release in Normal Volunteers and Patients with Secretory Pituitary Tumors

Cited by 26 publications

References 3 publications

Influence of Different Serotonin Receptor Subtypes On Growth Hormone Secretion

Influence of Different Serotonin Receptor Subtypes On Growth Hormone Secretion

Effect of L-Tryptophan on Apomorphine-Induced Growth Hormone Secretion in Normal Subjects

The Effect of TRH, Cyproheptadine and Pimozide on the Growth Hormone Response to Intramuscular Glucagon

Contact Info

Product

Resources

About