Inhibition of GH in maternal separation may be mediated through altered serotonergic activity at 5-HT2A and 5-HT2C Receptors

doi:10.1016/0306-4530(95)00043-7

Psychoneuroendocrinology

Volume 21, Issue 2, February 1996, Pages 219-235

https://doi.org/10.1016/0306-4530(95)00043-7 Get rights and content

Abstract

The hyposecretion of growth hormone (GH) in maternal separation (MS) of rat pups is remarkably similar to the specific suppression of GH secretion to evocative tests in infants diagnosed with Reactive Attachment Disorder of Infancy (RADI). Growth hormone-releasing factor (GRF) and somatostatin (SS) provide opposing regulation of GH secretion, and both are modified by noradrenergic and serotonergic stimuli in neonatal and adult rats. In this study, GRF administration reversed MS-induced suppression of GH secretion in 10-day-old pups, but this action of GRF was prevented by pretreatment with cyproheptadine (Cypro), a serotonergic antagonist. The normalization of GH secretion after return to the dam was not altered by pretreatment with SS. Indirect 5-HT agonists, fluoxetine (FLX) and 5-HTP, both stimulated GH secretion in 10-day-old pups. All mixed serotonin- and 5-H_1A-receptor agonists suppressed GH secretion in 10-day-old pups. Antagonists Cypro and ketanserin (Ket) suppressed FLX-induced GH secretion. In contrast, only Cypro suppressed 5-HTP-induced GH secretion. Maternal separation inhibited GH secretion stimulated by 5-HTP, but not by FLX. The serotonergic pathway acting on 5-HT_2A receptors may be obligatory for GRF-mediated stimulation and is sensitive to inhibition by Cypro. In addition, a Ket-sensitive serotonergic parallel pathway acting on 5-HT_2C receptors may also stimulate GH secretion by acting on GRF or SS. However, only the obligate 5-HT_2A pathway appears to be suppressed in MS. These data and observations by others indicate that specific suppression of GH secretion in MS may derive from a reduction in GRF release through noradrenergic neurons, possibly impinging upon serotonergic terminals in the hypothalamus. This study may also provide insight into mechanisms by which GH secretion is suppressed in humans with RADI.

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Inhibition of GH in maternal separation may be mediated through altered serotonergic activity at 5-HT2A and 5-HT2C Receptors

Abstract

Neuropharmacology

Trends Pharmacol Sci

Reg Peptides

Life Sci

Life Sci

J Pediatr

Pharm Biochem Behav

Life Sci

Pharm Biochem Behav

Life Sci

Life Sci

Pharm Biochem Behav

J Pediatr

Life Sci

Brain Res Mol Brain Res

Eur J Pharmacol

Brain Res

Brain Res Mol Brain Res

N Engl J Med

Child Dev

Horm Metab Res

Chemical-feedback regulation of serotonin-containing neurons in brain

Ann NY Acad Sci

Serotoninergic control of prolactin secretion in prepubertal male rats

Eur J Endocrinol

Somatostatin: regulation of secretion

Neuroendocrinology

L-tryptophan injection enhances pulsatile growth hormone secretion in the rat

Endocrinology

Maternal behavior as a regulator of polyamine biosynthesis in brain and heart of the developing rat pup

Science

In vivo effects of serotonergic agents on alpha-melanocyte-stimulating hormone secretion

Neuroendocrinology

Growth hormone (GH) autofeedback action in the neonatal rat: involvement of GH-releasing hormone and somatostatin

J Endocrinol

Epinephrine mediates the growth hormone-releasing effect of galanin in infant rats

Endocrinology

Human pancreatic growth hormone (GH)-releasing hormone stimulates GH synthesis and release in infant rats. An in vivo study

Endocrinology

Effect of intraventricular injection of dopamine, norepinephrine, acetylcholine, and 5-hydroxytryptamine on immunoreactive somatostatin release into rat hypophyseal portal blood

Endocrinology

Effect of 5-hydroxytryptophan on prolactin and growth hormone release in the infant rat: evidence for different neurotransmitter mediation

Neuroendocrinology

Central and peripheral injections of the 5-HT2 agonist, 1-(2,5dimethoxy-4-iodophenyl)-2-aminopropane, modify cardiovascular function through different mechanisms

J Pharmacol Exp Ther

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Endocrinology

Effect of ether stress on growth hormone during development in the neonatal rat

Neuroendocrinology

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Comm Psychopharmacol

Effects of tactile/kinesthetic stimulation in pre-term neonates

Pediatrics

Inhibition of GH in maternal separation may be mediated through altered serotonergic activity at 5-HT_2A and 5-HT_2C Receptors