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Failure of the putative neuropeptide Y antagonists, benextramine and PYX‐2, to inhibit Y 2 receptors in rat isolated prostatic vas deferens
Author(s) -
Palea S.,
Corsi M.,
Rimland J.M.,
Trist D.G.,
Ratti E.
Publication year - 1995
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1995.tb15086.x
Subject(s) - vas deferens , endocrinology , medicine , neuropeptide y receptor , purinergic receptor , prazosin , agonist , receptor , neurotransmitter , chemistry , biology , stimulation , antagonist , suramin , neuropeptide
1 The pharmacological activity of neuropeptide Y (NPY) and some analogues in inhibiting the twitch contractions induced by electrical stimulation (single pulses at 25 V, 0.15 Hz, 1 ms) in the prostatic portion of the rat isolated vas deferens was investigated. The rank order of agonist potency was: PYY > NPY 2–36 > NPY >> NPY 13–36 >> NPY >8–36 >>> [Leu 31 , Pro 34 ]NPY = hPP, which is consistent with the activation of a Y 2 receptor. 2 The putative Y 1 and Y 2 antagonist, benextramine (BXT), incubated at 100 μ m for 10 or 60 min, was ineffective against PYY‐induced inhibition of the twitch response, suggesting that the prejunctional Y 2 receptor in this tissue is different from the postjunctional one reported in the literature to be sensitive to BXT blockade. 3 The putative NPY antagonist, PYX‐2, incubated at 1 μ m for 20 min, was completely ineffective in antagonizing PYY‐induced inhibition of twitches. 4 The twitch response was totally inhibited by suramin (100 μ m ) but was little affected by prazosin (1 μ m ). Futhermore, NPY was without effect on the dose‐response curve to ATP in resting conditions. Taken together, these results suggest that in our paradigm, NPY inhibits the release of a purinergic neurotransmitter which mediates contraction of the prostatic portion of the rat vas deferens.