Studies of the role of the N-methyl-D-aspartate (NMDA) receptor in the hypothalamic control of prolactin secretion

Muhammad Arslan, Clifford R. Pohl, M. Susan Smith, Tony M. Plant

    Research output: Contribution to journalArticle

    31 Scopus citations

    Abstract

    To further examine the role of excitatory amino acids in the control of prolactin (PRL) secretion, the effects of administering agonist and an antagonist of the N-methyl-D-aspartate (NMDA) receptor on plasma PRL concentrations were examined in the adult male rat. Animals of the Sprague-Dawley strain weighing 250-300 g were implanted with an indwelling cardiac catheter via the right jugular vein. Blood samples were collected through the catheter at 5 min intervals for 40 min, beginning 5 min before the iv administration of drug or the saline vehicle (V). Plasma PRL and luteinizing hormone (LH) concentrations were estimated using RIAs. Groups of animals (n=5-7) received N-methyl-D, L-aspartate (NMA), D, L-2-amino-5-phosphonopentanoic acid (AP5), AP5 and NMA, norvaline (NOR), or V. The effects of administering the NMDA receptor antagonist alone were studied on two separate occasions. Injection of NMA (4.5 mg/rat) resulted in unambiguous PRL and LH discharges. Treatment with AP5 (9 mg/rat) 1 min prior to NMA administration completely blocked the LH releasing action of NMA, but did not significantly alter the discharge of PRL. Injection of AP5, alone, generally elicited a distinct and robust discharge of PRL, although plasma LH levels in these animals remained unchanged. NOR, an amino acid structurally related to AP5, administered at a dose (5.3 mg/animal) isomolar to that of AP5, was without effect on PRL and LH secretion, as was injection of V alone. These findings suggest that neuroexcitatory amino acids acting at the NMDA receptor may play a role in modulating the activity of neuronal systems that govern the release of both PRL releasing factor (PRF) and PRL inhibiting factor (PIF) into hypophysial portal blood.

    Original languageEnglish (US)
    Pages (from-to)295-300
    Number of pages6
    JournalLife Sciences
    Volume50
    Issue number4
    DOIs
    StatePublished - 1992

    ASJC Scopus subject areas

    • Biochemistry, Genetics and Molecular Biology(all)
    • Pharmacology, Toxicology and Pharmaceutics(all)

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