Pharmacological characterization of neuropeptide Y and noradrenaline mechanisms in sympathetic control of pig spleen

https://doi.org/10.1016/0014-2999(89)90401-9Get rights and content

Abstract

The mechanism underlying the functional effects of neuropeptide Y (NPY)-like immunoreactivity (LI) and noradrenaline (NA) and their release evoked by nerve stimulation were studied with the blood-perfused pig spleen in vivo. Infusion of selective agonists and antagonists suggested the presence of α1- and β2-adrenoceptors mediating vasoconstriction and vasodilation, respectively. NPY caused a slight inhibition of stimulation-evoked [3H]NA release and a clearcut non-adrenergic vasoconstriction. Local pretreatment with phentolamine and prazosin as well as with clonidine and UK 14304 reduced the perfusion pressure response to nerve stimulation. Phentolamine, yohimbine and idazoxan enhanced while clonidine and UK 14304 decreased the output of [3H]NA or NA and NPY-LI. The subsequent addition of propanolol to the α-adrenoceptor antagonists was followed by reappearance at a considerable portion of the perfusion pressure response while the output of [3H]NA or NA and NPY-LI was slightly reduced. It is concluded that NPY exerts pre- and post-junctional actions in pig spleen that regulate both NA release and vascular tone. α1-Adrenoceptors are mainly involved in vasoconstriction, and prejunctional α2 mechanisms inhibit both NA and NPY release at a low frequency of stimulation. β2-Adrenoceptors mediate vasodilation when NA release is enhanced with a minor effect on mediator secretion.

References (37)

  • J.M. Lundberg et al.

    Frequency and reserpine dependent chemical coding of sympathetic transmission: Differential release of noradrenaline and neuropeptide Y from pig spleen

    Neurosci. Lett.

    (1986)
  • J.M. Lundberg et al.

    High levels of neuropeptide Y in peripheral noradrenergic neurons in various mammals including man

    Neurosci. Lett.

    (1983)
  • A. Saria et al.

    Evidence for specific neuropeptide Y binding sites in rat braim synaptosomes

    European J. Pharmacol.

    (1984)
  • L. Stjärne et al.

    Neuropeptide Y - a cotransmitter with noradrenaline and adenosine-5′-triophosphate in the sympathetic nervews of the mouse vas deferens? A combined biochemical, physiological and electropharmacological study

    Neuroscience

    (1986)
  • A. Undén et al.

    Binding of neuropeptide Y to rat brain membranes

    FEBS Lett.

    (1984)
  • S.M. Celuch et al.

    Stimulation of presynaptic β-adrenoceptors enhances (3H)-noradrenaline release during nerve stimulation in the perfused cat spleen

    Br. J. Pharmacol.

    (1978)
  • L.X. Cubeddu et al.

    Release of norepinephrine and dopamine-beta-hydroxylase by nerve stimulation. Role of neuronal and extraneuronal uptake and of alpha-presynaptic receptors

    J. Pharmacol. Exp. Ther.

    (1974)
  • C. Dahlöf

    Studies on beta-adrenoceptor mediated facilitation of sympathetic neurotransmission

    Acta Physiol. Scand.

    (1981)
  • Cited by (0)

    View full text