Involvement of Vasopressin in Histamine- and Stress-Induced Prolactin Release: Permissive, Mediating or Potentiating Role?

Abstract

Arginine vasopressin (AVP) appears to be involved in the histamine (HA)-and stress-induced prolactin (PRL) release. The present investigation was performed in male rats to clarify whether the role of AVP in HA- and restraint stress-induced secretion of PRL is mediating (i.e., the effect of HA or stress is transmitted via AVP) or permissive (i.e., the presence of AVP is required to obtain a stimulatory effect of HA or stress on PRL secretion). Furthermore, we studied whether AVP possessed a potentiating effect on the HA- or stress-induced PRL release. PRL secretion was stimulated 14- to 17-fold by intra-cerebroventricular infusion of HA (270 nmol) or by 5 min of restraint stress. These effects were inhibited about 80% by immunoneutralization of endogenous AVP with a specific AVP antiserum (abAVP). When specific AVP V₁- or V₂-receptor agonists, which were not bound by the AVP antiserum, were administered intravenously together with the AVP antiserum, the PRL response to HA or restraint stress was partly ( > 50%) reestablished. This effect was observed at low (1.2 or 0.1 nmol) as well as high (3.8 or 0.4 nmol) doses of agonists and when these were administered alone or in combination. In non-immunoneutralized animals, separate administration of agonists at low or high doses as well as combined administration of agonists at low doses had no or only a minor effect on PRL secretion, while combined administration of Viand V2-agonist in high doses stimulated PRL secretion 6-fold. Taken together, these observations indicate that AVP has a permissive role. Since the response to HA or restraint stress was only partly reestablished by AVP agonists, it appears that AVP plays a mediating role as well. When AVP was administered in a dose (240 pmol) which had no PRL-releasing effect in itself, the PRL-stimulating effect of a submaximal HA dose or restraint stress was not altered. This excludes a potentiating effect of AVP. We suggest that AVP (probably of hypothalamic origin) has a permissive and probably also a mediating effect on the PRL response to HA or restraint stress.

Selective Inhibition of Magnocellular Vasopressin Neurons by Hypoosmolality: Effect on Histamine- and Stress-Induced Secretion of Adrenocorticotropin and Prolactin

“…20–30%). However, in a previous study we demonstrated that AVP, in addition to a permissive role, does have a mediating role [6]. Therefore, the present data indicate that the previously observed mediating action must relate to AVP of parvocellular origin.…”

“…ACTH and PRL release is transmitted via release of AVP). Several experimental paradigms may be used in order to discriminate between the possible routes, sources and modes of actions of AVP in HA- and stress-induced ACTH and PRL secretion [4, 5, 6, 7]. Among these methods one was especially designed to discriminate between the permissive and mediating roles of AVP [6, 7].…”

Effect of Selective Blockade of Catecholaminergic Alpha and Beta Receptors on Histamine-Induced Release of Corticotropin and Prolactin

“…However, in other studies, HA did not affect the turnover of dopamine in the median eminence [17, 18]. Other studies have indicated that the effect of HA is mediated via an interaction with vasopressinergic as well as serotonergic neurons [14, 19, 20, 21]. …”

“…The ACTH antiserum (generously provided by the National Pituitary Agency, National Institute of Health) does not cross-react with β-endorphin or β-LPH and has less than 0.4% cross-reactivity with α- and β-melanocyte stimulating hormone. Synthetic human ACTH [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39](generously provided by the National Pituitary Agency, National Institute of Health) served as reference preparation and iodination. The least detectable quantity of ACTH was 1 pmol/l plasma, and the intra- and interassay coefficients of variation were 4 and 5%.…”