Evidence for involvement of α-adrenergic receptors in norepinephrine-induced prostaglandin E2 and luteinizing hormone-releasing hormone release from the median eminence

Sergio Ojeda, A. Negro-Vilar, S. M. McCann

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Abstract

Studies were conducted to determine if the stimulatory effect that norepinephrine (NE) exerts on the release of prostaglandin E2 (PGE2) and LHRH from the median eminence is mediated by α- or β-adrenergic receptors. Incubation of median eminence fragments from adult male rats with different concentrations of phentolamine, an α-receptor antagonist, resulted in a dose-related inhibition of the release of both PGE2 and LHRH induced by NE, with an IC50 of 3.5 x 10-7 and 0.9 x 10-7 M for PGE2 and LHRH, respectively. Complete suppression of the NE effects was observed with a phentolamine concentration of 5 x 10-6 M. This dose also reduced basal PGE2 and LHRH release. In contrast to phentolamine, the β-receptor antagonist propranolol, tested at a concentration of 5 x 10-6 M, was completely ineffective in altering the stimulatory effect of NE on either PGE2 or LHRH release. Moreover (and as previously observed for LHRH), blockade of dopaminergic receptors with Pimozide (10-6 M) failed to inhibit the release of PGE2 induced by NE, thus indicating that the stimulatory effect of NE is not mediated by a dopaminergic mechanism. It is concluded that NE stimulates the release of PGE2 and LHRH from nerve terminals of the median eminence by first interacting with an α-adrenergic receptor.

Original languageEnglish (US)
Pages (from-to)409-412
Number of pages4
JournalEndocrinology
Volume110
Issue number2
StatePublished - 1982
Externally publishedYes

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Median Eminence
Dinoprostone
Gonadotropin-Releasing Hormone
Adrenergic Receptors
Norepinephrine
Phentolamine
Pimozide
Propranolol
Inhibitory Concentration 50

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

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title = "Evidence for involvement of α-adrenergic receptors in norepinephrine-induced prostaglandin E2 and luteinizing hormone-releasing hormone release from the median eminence",
abstract = "Studies were conducted to determine if the stimulatory effect that norepinephrine (NE) exerts on the release of prostaglandin E2 (PGE2) and LHRH from the median eminence is mediated by α- or β-adrenergic receptors. Incubation of median eminence fragments from adult male rats with different concentrations of phentolamine, an α-receptor antagonist, resulted in a dose-related inhibition of the release of both PGE2 and LHRH induced by NE, with an IC50 of 3.5 x 10-7 and 0.9 x 10-7 M for PGE2 and LHRH, respectively. Complete suppression of the NE effects was observed with a phentolamine concentration of 5 x 10-6 M. This dose also reduced basal PGE2 and LHRH release. In contrast to phentolamine, the β-receptor antagonist propranolol, tested at a concentration of 5 x 10-6 M, was completely ineffective in altering the stimulatory effect of NE on either PGE2 or LHRH release. Moreover (and as previously observed for LHRH), blockade of dopaminergic receptors with Pimozide (10-6 M) failed to inhibit the release of PGE2 induced by NE, thus indicating that the stimulatory effect of NE is not mediated by a dopaminergic mechanism. It is concluded that NE stimulates the release of PGE2 and LHRH from nerve terminals of the median eminence by first interacting with an α-adrenergic receptor.",
author = "Sergio Ojeda and A. Negro-Vilar and McCann, {S. M.}",
year = "1982",
language = "English (US)",
volume = "110",
pages = "409--412",
journal = "Endocrinology",
issn = "0013-7227",
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T1 - Evidence for involvement of α-adrenergic receptors in norepinephrine-induced prostaglandin E2 and luteinizing hormone-releasing hormone release from the median eminence

AU - Ojeda, Sergio

AU - Negro-Vilar, A.

AU - McCann, S. M.

PY - 1982

Y1 - 1982

N2 - Studies were conducted to determine if the stimulatory effect that norepinephrine (NE) exerts on the release of prostaglandin E2 (PGE2) and LHRH from the median eminence is mediated by α- or β-adrenergic receptors. Incubation of median eminence fragments from adult male rats with different concentrations of phentolamine, an α-receptor antagonist, resulted in a dose-related inhibition of the release of both PGE2 and LHRH induced by NE, with an IC50 of 3.5 x 10-7 and 0.9 x 10-7 M for PGE2 and LHRH, respectively. Complete suppression of the NE effects was observed with a phentolamine concentration of 5 x 10-6 M. This dose also reduced basal PGE2 and LHRH release. In contrast to phentolamine, the β-receptor antagonist propranolol, tested at a concentration of 5 x 10-6 M, was completely ineffective in altering the stimulatory effect of NE on either PGE2 or LHRH release. Moreover (and as previously observed for LHRH), blockade of dopaminergic receptors with Pimozide (10-6 M) failed to inhibit the release of PGE2 induced by NE, thus indicating that the stimulatory effect of NE is not mediated by a dopaminergic mechanism. It is concluded that NE stimulates the release of PGE2 and LHRH from nerve terminals of the median eminence by first interacting with an α-adrenergic receptor.

AB - Studies were conducted to determine if the stimulatory effect that norepinephrine (NE) exerts on the release of prostaglandin E2 (PGE2) and LHRH from the median eminence is mediated by α- or β-adrenergic receptors. Incubation of median eminence fragments from adult male rats with different concentrations of phentolamine, an α-receptor antagonist, resulted in a dose-related inhibition of the release of both PGE2 and LHRH induced by NE, with an IC50 of 3.5 x 10-7 and 0.9 x 10-7 M for PGE2 and LHRH, respectively. Complete suppression of the NE effects was observed with a phentolamine concentration of 5 x 10-6 M. This dose also reduced basal PGE2 and LHRH release. In contrast to phentolamine, the β-receptor antagonist propranolol, tested at a concentration of 5 x 10-6 M, was completely ineffective in altering the stimulatory effect of NE on either PGE2 or LHRH release. Moreover (and as previously observed for LHRH), blockade of dopaminergic receptors with Pimozide (10-6 M) failed to inhibit the release of PGE2 induced by NE, thus indicating that the stimulatory effect of NE is not mediated by a dopaminergic mechanism. It is concluded that NE stimulates the release of PGE2 and LHRH from nerve terminals of the median eminence by first interacting with an α-adrenergic receptor.

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