TY - JOUR

T1 - Interactions of histaminergic and serotonergic neurons in the hypothalamic regulation of prolactin and ACTH secretion

AU - Jørgensen, Henrik

AU - Knigge, Ulrich

AU - Kjær, Andreas

AU - Warberg, Jørgen

PY - 1996

Y1 - 1996

N2 - Serotonergic and histaminergic neuronal systems are both involved in mediation of the stress-induced release of thepituitary hormones prolactin (PRL) and ACTH. We investigated the possibility of an interaction between serotonin (5-HT) and histamine (HA) in regulation of PRL and ACTH secretion in conscious male rats. Animals were pretreated systemically with antagonists to 5-HT1, 5-HT2 or 5-HT3 receptors prior to intracerebroventricular (icv) administration of HA. The 5-HT1+2 receptor antagonist methysergide prevented and the 5-HT2 receptor antagonist LY 53857 attenuated the HA-induced PRL release while the 5-HT3 receptor antagonist ondansetron had no effect on this response. None of the three 5-HT receptor antagonists affected the ACTH response to HA. Specific blockade of HA synthesis by α-fluoromethylhistidine or blockade of postsynaptic HA receptors byicv infusion of the H1 receptor antagonist mepyramine or the H2 receptor antagonist cimetidine inhibited the PRL response to 5-HT or to the 5-HT precursor 5-hydroxytryptophan (5-HTP) given in combination with the 5-HT reuptakeinhibitor fluoxetine (Fix). Blockade of the histaminergic system had no effect on the ACTH response to serotonergic stimulation. The H3 receptors are inhibitory HA receptors. Systemic pretreatment with the H3 receptor agonist R(α)methylhistamine, or the H3 receptor antagonist thioperamide had no effect on the hormone response to activation of the serotonergicsystem by 5-HTP plus Flx. We conclude that the serotonergic and histaminergic neuronal systems interact in their stimulationof PRL secretion, but not in their stimulation of ACTH secretion. This interaction involves serotonergic 5-HT1 and 5-HT2 receptors and histaminergic H1 and H2 receptors. Furthermore, the previously observed inhibitory effect of the H3 receptor agonist R(α)methylhistamine on stress-induced PRL and ACTH release seems not to be exerted by activation of presynaptic H3 receptors located on serotonergic neurons but rather on histaminergic neurons.

AB - Serotonergic and histaminergic neuronal systems are both involved in mediation of the stress-induced release of thepituitary hormones prolactin (PRL) and ACTH. We investigated the possibility of an interaction between serotonin (5-HT) and histamine (HA) in regulation of PRL and ACTH secretion in conscious male rats. Animals were pretreated systemically with antagonists to 5-HT1, 5-HT2 or 5-HT3 receptors prior to intracerebroventricular (icv) administration of HA. The 5-HT1+2 receptor antagonist methysergide prevented and the 5-HT2 receptor antagonist LY 53857 attenuated the HA-induced PRL release while the 5-HT3 receptor antagonist ondansetron had no effect on this response. None of the three 5-HT receptor antagonists affected the ACTH response to HA. Specific blockade of HA synthesis by α-fluoromethylhistidine or blockade of postsynaptic HA receptors byicv infusion of the H1 receptor antagonist mepyramine or the H2 receptor antagonist cimetidine inhibited the PRL response to 5-HT or to the 5-HT precursor 5-hydroxytryptophan (5-HTP) given in combination with the 5-HT reuptakeinhibitor fluoxetine (Fix). Blockade of the histaminergic system had no effect on the ACTH response to serotonergic stimulation. The H3 receptors are inhibitory HA receptors. Systemic pretreatment with the H3 receptor agonist R(α)methylhistamine, or the H3 receptor antagonist thioperamide had no effect on the hormone response to activation of the serotonergicsystem by 5-HTP plus Flx. We conclude that the serotonergic and histaminergic neuronal systems interact in their stimulationof PRL secretion, but not in their stimulation of ACTH secretion. This interaction involves serotonergic 5-HT1 and 5-HT2 receptors and histaminergic H1 and H2 receptors. Furthermore, the previously observed inhibitory effect of the H3 receptor agonist R(α)methylhistamine on stress-induced PRL and ACTH release seems not to be exerted by activation of presynaptic H3 receptors located on serotonergic neurons but rather on histaminergic neurons.

KW - Corticotropin

KW - Histamine

KW - Histamine receptors

KW - Prolactin

KW - Serotonin

KW - Serotonin receptors

UR - http://www.scopus.com/inward/record.url?scp=0029910724&partnerID=8YFLogxK

U2 - 10.1159/000127136

DO - 10.1159/000127136

M3 - Journal article

C2 - 8930933

AN - SCOPUS:0029910724

VL - 64

SP - 329

EP - 336

JO - Neuroendocrinology

JF - Neuroendocrinology

SN - 0028-3835

IS - 5

ER -