Effect of Adrenergic-blocking Agents on Plasma Growth Hormone Response to L-5-Hydroxytryptophan (5-HTP) in Man

Nakai, Yoshikatsu; Imura, Hiroo

doi:10.1507/endocrj1954.21.493

Cited by 8 publications

(3 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are abundant data indicating that centrally released norepinephrine or epi nephrine acts via «-adrenergic receptors to increase growth hormone secretion [II,17]. Nakai and Imura [14] have re ported that the increase in plasma growth hormone pro duced by 5-HTP in humans is blocked by a-adrenergic blocking drugs. Therefore, the data are consistent with the hypothesis that the growth hormone stimulating activity of 5-HTP is due to central release of catecholamines rather than serotonin.…”

Section: Discussionmentioning

confidence: 99%

“…release of norepinephrine inhibits stress-induced ACTH secretion and stimulates growth hormone secretion in dogs [17]. The serotonin precursor 5-hydroxytryptophan (5-HTP) also in hibits ACTH secretion and stimulates growth hormone se cretion [14;Ganong. unpublished observations], but it has not been proved that these effects are due to the release of serotonin. Data in the literature on the effects of central se rotonin on ACTH secretion are conflicting, with some in vestigators claiming that serotonergic discharge increases ACTH secretion, others claiming that it decreases ACTH secretion, and still others claiming that it has no effect [16].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Evidence that the Effects of 5-Hydroxytryptophan on the Secretion of ACTH and Growth Hormone in Dogs are not Mediated by Central Release of Serotonin

Zimmermann¹,

Kaplan²,

Ganong³

1982

Neuroendocrinology

View full text Add to dashboard Cite

5-Hydroxytryptophan (5-HTP) was found to lower plasma 11-oxycorticoids and increase plasma growth hormone in anesthetized dogs. To determine whether these effects were mediated by release of serotonin, 5-HTP and L-tryptophan were injected intravenously alone and after treatment with various drugs. The decrease in corticoids produced by 5-HTP was unaffected by intravenous carbidopa and metergoline, but was abolished by intravenous benserazide in a dose that inhibits central 5-HTP and dopa decarboxylase, and by a small dose of phenoxybenzamine in the third ventricle. Adrenal sensitivity to ACTH was unaffected by 5-HTP. L-Tryptophan did not decrease plasma corticoids; instead it produced a small increase. The increase in plasma growth hormone produced by 5-HTP was potentiated by carbidopa and abolished by benserazide. L-Tryptophan did not increase plasma growth hormone; instead it produced no change or in some instances a decrease. Plasma growth hormone declined after administration of phenoxybenzamine in the third ventricle, and the decline continued after administration of 5-HTP. The data indicate that the effects of 5-HTP on ACTH and growth hormone secretion are not due to central release of serotonin and suggest that they are due instead to serotonin-induced release of catecholamines from catecholamine-secreting neurons.

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Evidence that the Effects of 5-Hydroxytryptophan on the Secretion of ACTH and Growth Hormone in Dogs are not Mediated by Central Release of Serotonin

Zimmermann¹,

Kaplan²,

Ganong³

1982

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…However, there is reason to believe it may be adrenergic. 5HTP is known to enter many different types of neurons, and to cause release of catecholamines as w ell as serotonin [7], and it has been reported that the growth hormone re sponse to 5UTP in rats and humans is blunted by drugs that block \-adrenergic receptors [3,22], Metergoline may have some dopaminergic activity and dopamine stimulates growth hormone secretion in some species. However, dop amine does not have any growth hormone stimulating activity in dogs [10.…”

Section: Discussionmentioning

confidence: 99%

Regulation of Prolactin and Growth Hormone Secretion

et al. 1980

View full text Add to dashboard Cite

A heterologous radioimmunoassay for canine prolactin was developed and used to study the role of catecholamines and indoleamines in the regulation of prolactin secretion in dogs. Female dogs were found to have a higher plasma prolactin concentration than male dogs. Thyrotropin-releasing hormone (TRH) increased plasma prolactin in male and female trained conscious dogs. L-Dopa blocked the increase produced by TRH, but this effect could be reversed by pretreatment with carbidopa, an inhibitor of the conversion of L-dopa to catecholamines outside the blood-brain barrier. The intravenous administration of the immediate precursor of serotonin, L-5-hydroxytryptophan (5HTP), caused an increase in plasma prolactin and growth hormone. The administration of the serotonin receptor blocker, metergoline, 18 and 3 h before 5HTP, significantly augmented the growth hormone response to 5HTP. In contrast, metergoline diminished the prolactin response to 5HTP. Pretreatment with carbidopa did not change the prolactin or growth hormone responses to 5HTP. These observations indicate that the dog is similar to other mammals in that females have greater plasma prolactin concentrations than males and TRH increases plasma prolactin. L-Dopa appears to act at a site outside the blood-brain barrier to prevent the prolactin response to TRH. The data suggest that 5HTP increases plasma prolactin via a serotonergic mechanism, whereas it increases plasma growth hormone via a different, nonserotonergic mechanism.

show abstract

Neurotransmitter control of growth hormone, thyrotropin and prolactin secretion

Genazzani²,

Casanueva

et al. 1980

J Endocrinol Invest

View full text Add to dashboard Cite

Effect of Adrenergic-blocking Agents on Plasma Growth Hormone Response to L-5-Hydroxytryptophan (5-HTP) in Man

Cited by 8 publications

References 11 publications

Evidence that the Effects of 5-Hydroxytryptophan on the Secretion of ACTH and Growth Hormone in Dogs are not Mediated by Central Release of Serotonin

Evidence that the Effects of 5-Hydroxytryptophan on the Secretion of ACTH and Growth Hormone in Dogs are not Mediated by Central Release of Serotonin

Regulation of Prolactin and Growth Hormone Secretion

Neurotransmitter control of growth hormone, thyrotropin and prolactin secretion

Contact Info

Product

Resources

About