Influence of Different Serotonin Receptor Subtypes On Growth Hormone Secretion

Valverde, I Salar; Peñalva, A; Diéguez, Carlos

doi:10.1159/000054530

Cited by 25 publications

(14 citation statements)

References 46 publications

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“…bolus at 0 min) at a dose (100 µg) which markedly increases GH secretion in dogs, as previously reported [19, 20]. …”

Section: Methodssupporting

confidence: 78%

“…bolus at 0 min, Peninsula Laboratories, Merseyside, UK) administered at a dose of 90 µg (based on previous reports by our group in dogs) [19, 20]. …”

Section: Methodsmentioning

confidence: 99%

“…The experiments were carried out on beagle dogs, a species which can be subjected to venepuncture after appropriate training without behavioural or hormonal manifestations of stress. Furthermore, many of the neuroendocrine mechanisms involved in GH control in dogs resemble more those of primates than of rats [18, 19, 20]. …”

Section: Introductionmentioning

confidence: 99%

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Involvement of Nitric Oxide in the Regulation of Growth Hormone Secretion in Dogs

et al. 2001

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Nitric oxide (NO) is a highly reactive gas that has been suggested to function as a neurotransmitter in the neuroendocrine system. In this work, we have evaluated the role of NO pathways in growth hormone (GH) secretion by assessing the effect of L-arginine infusion, a precursor of NO formation, and L-NAME, a nitric oxide synthase (NOS) inhibitor. The experiments were carried out on 7 adult beagle dogs. A saline infusion was carried out on all the dogs as a control test. L-arginine (infusion i.v. 10 g in 100 ml of saline, from t = 0 to 30 min) and L-nitro-arginine-methyl ester, L-NAME (infusion of 300 µg/kg in 120 ml of saline, from t = –30 to 45 min) were administered alone and together with growth hormone-releasing hormone (GHRH) (i.v. bolus at 0 min, at a dose of 100 µg), the synthetic GH secretagogue GHRP-6 (i.v. bolus at 0 min, at a dose of 90 µg), and the 5-HT1D serotonin receptor agonist sumatriptan, SUM (s.c. injection at the dose of 3 mg). Plasma cGH was determined by RIA. Results were evaluated by one-way analysis of variance, followed by the Newman-Keuls test for multiple comparisons. L-arginine administration resulted in a slight increase in plasma cGH in comparison with saline controls. Combined administration of L-arginine and GHRH enhanced cGH release in comparison with GHRH alone. L-NAME alone did not modify baseline cGH levels, but completely suppressed the GH release induced by GHRH or GHRP-6. It also strongly reduced, but did not abolish the effect of the two peptides (GHRH plus GHRP-6) administered together. Finally, administration of the 5-HT1D agonist SUM induced a significant cGH secretion in all dogs, a response which was not modified when L-NAME was administered in combination with SUM. In conclusion, our data show that inhibition of NO blunts both GHRH or GHRP-6-induced cGH release, and are compatible with the hypothesis that it acts by decreasing hypothalamic somatostatin release.

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“…bolus at 0 min) at a dose (100 µg) which markedly increases GH secretion in dogs, as previously reported [19, 20]. …”

Section: Methodssupporting

confidence: 78%

“…bolus at 0 min, Peninsula Laboratories, Merseyside, UK) administered at a dose of 90 µg (based on previous reports by our group in dogs) [19, 20]. …”

Section: Methodsmentioning

confidence: 99%

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Involvement of Nitric Oxide in the Regulation of Growth Hormone Secretion in Dogs

et al. 2001

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“…It is possible that the stimulatory effect of serotonin on GH secretion is limited to specific periods of development. The serotoninergic 5-HT 1 and 5-HT 2 receptor subtypes have been shown to be involved as stimulatory elements in the control of GH in dogs (37) and in humans (38), whereas GH secretion seems to be independent of the degree of activation of 5-HT 3 receptors (37). In neonatal rats, it has been proposed that changes in serotoninergic activity at 5-HT 2 receptors mediates the inhibition of GH secretion in maternal separation (31).…”

Section: Discussionmentioning

confidence: 99%

5-HT1 and 5-HT2 receptor agonists blunt +/- -alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-stimulated GH secretion in prepubertal male rats

Pinilla

González²,

Tena‐Sempere³

et al. 2001

European Journal of Endocrinology

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Objective: Excitatory amino acids, g-amino butyric acid (GABA), serotonin and catecholamines are involved in the control of GH secretion. The actions of these neurotransmitters are interconnected, and recently we showed that the stimulatory effect of GABA was blocked by MK-801, an antagonist of N-methyl-D-aspartate receptors. The present experiments were carried out to analyze the interrelationships between (^)-a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors and serotoninergic and catecholaminergic pathways in the control of GH secretion in prepubertal (16±23-day-old) male rats. Design and Methods: The GH response to AMPA was analyzed in animals pretreated with 5-hydroxytryptophan methyl ester (5-HTP) plus fluoxetine (a precursor of 5-hydroxytryptamine (5-HT) synthesis and a blocker of 5-HT re-uptake), R (+)-8-hydroxydipropylaminotetralin hydrobromide (8-OH-DPAT, an agonist of the 5-HT 1 receptors), (^)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) and a-methyl-5-hydroxytryptamine (agonists of 5-HT 2 receptors), I-phenylbiguanide (an agonist of 5-HT 3 receptors), or a-methyl-p-tyrosine (a-MPT) and diethyldithiocarbamate (DDC) (blockers of catecholamine synthesis). Results: Basal GH secretion remained unchanged in prepubertal rats after activation of the serotoninergic system or blockade of catecholamine synthesis. The stimulatory effect of AMPA on GH secretion was blocked after activation of the serotoninergic system, through specific 5-HT 1 and 5-HT 2 receptor agonists. In contrast, activation of 5-HT 3 receptors potentiated AMPA-stimulated GH secretion. Conclusions: Serotoninergic receptors modulate the stimulatory effect of AMPA on GH secretion in prepubertal male rats.

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“…A number of studies showed a positive effect of brain serotonin on the secretion of adrenocorticotropic hormone (Jørgensen, 2007). The stimulating effect of the brain serotonergic system on growth hormone secretion can be initiated by either growth hormone-releasing hormone release from the arcuate nucleus (Vijayan et al, 1978;Murakami et al, 1986; or the suppression of somatostatin release from the paraventricular nucleus (Mota et al, 1995;Valverde et al, 2000). A majority of data indicate a complex mechanism of the serotoninregulated thyroid-stimulating hormone (TSH) secretion which may occur at the level of the hypothalamus (inhibition of thyrotropinreleasing hormone release or somatostatin secretion) or pituitary gland (stimulation of TSH secretion) (Abrahamson et al, 1987;Toivonen et al, 1990;Masalova and Sapronov, 2009).…”

Section: Introductionmentioning

confidence: 99%

Damage to the Brain Serotonergic System Increases the Expression of Liver Cytochrome P450

et al. 2015

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Genes coding for cytochrome P450 are regulated by endogenous hormones such as the growth hormone, corticosteroids, thyroid, and sex hormones. Secretion of these hormones is regulated by the respective hypothalamus-pituitary-secretory organ axes. Since the brain sends its serotonergic projections from the raphe nuclei to the hypothalamus, we have assumed that damage to these nuclei may affect the neuroendocrine regulation of cytochrome P450 expression in the liver. Thereby, 5,7-dihydroxytryptamine (5,7-DHT), a serotonergic neurotoxin, was injected into the dorsal and median raphe nuclei of male Wistar rats. Ten days after the neurotoxin injections, the brain concentrations of neurotransmitters, serum hormone, and cytokine levels, as well as the expression of cytochrome P450 in the liver were measured. Injection of 5,7-DHT decreased serotonin concentration in the brain followed by a significant rise in the levels of the growth hormone, corticosterone, and testosterone, and a drop in triiodothyronine concentration in the serum. No changes in interleukin (IL) levels (IL-2 and IL-6) were observed. Simultaneously, the activity and protein level of liver CYP1A, CYP3A1, and CYP2C11 rose (the activity of CYP2A/2B/2C6/2D was not significantly changed). Similarly, the mRNA levels of CYP1A1, CYP1A2, CYP2C11, and CYP3A1 were elevated. This is the first report demonstrating the effect of intracerebral administration of serotonergic neurotoxin on liver cytochrome P450. The obtained results indicate involvement of the brain serotonergic system in the neuroendocrine regulation of liver cytochrome P450 expression. The physiologic and pharmacological significance of the findings is discussed.

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Influence of Different Serotonin Receptor Subtypes On Growth Hormone Secretion

Cited by 25 publications

References 46 publications

Involvement of Nitric Oxide in the Regulation of Growth Hormone Secretion in Dogs

Involvement of Nitric Oxide in the Regulation of Growth Hormone Secretion in Dogs

5-HT1 and 5-HT2 receptor agonists blunt +/- -alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-stimulated GH secretion in prepubertal male rats

Damage to the Brain Serotonergic System Increases the Expression of Liver Cytochrome P450

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