Microinjection of the preferential dopamine receptor D3 agonist 7-hydroxy-N,N-di-n-propylaminotetralin hydrobromide into the hypothalamic medial preoptic area induced ejaculation in anesthetized rats

Neuroscience. 2007 Nov 9;149(3):636-41. doi: 10.1016/j.neuroscience.2007.06.051. Epub 2007 Jul 20.

Abstract

The pivotal role of the medial preoptic area (MPOA) of the hypothalamus in the dopaminergic cerebral control of ejaculation has been investigated for years; nevertheless the function of different dopamine receptors subclasses and their exact interrelations merit additional research. One hundred nanograms of a preferential D(3) agonist 7-OH-DPAT (7-hydroxy-N,N-di-n-propylaminotetralin hydrobromide) was microinjected unilaterally into the MPOA of male rats anesthetized with urethane. An ejaculation-related response (bulbospongiosus muscles rhythmic contractions and/or seminal vesicle pressure increases and/or expulsion of a semen plug) was observed in 8 of 10 rats devoid of sexual stimuli, while a similar response was observed in only one rat administered with 10 ng of 7-OH-DPAT. The effect of 7-OH-DPAT 100 ng was mostly abolished by simultaneous MPOA microinjection of 300 ng of a preferential D(3) antagonist N-[(n-butyl-2-pyrrolidinyl) methyl]-1-methoxy-4-cyanonaphthalene-2-carboxamide tartrate (nafadotride). Our results support the hypothesis that supraspinal command of ejaculation is mediated by D(2)-like receptors, probably by D(3) receptors, in the MPOA, and draw attention to the idea of these receptors serving as a promising target for pharmacological treatment of human ejaculatory disorders.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Pressure / drug effects
  • Dopamine Agonists / pharmacology
  • Dopamine Antagonists / pharmacology
  • Dose-Response Relationship, Drug
  • Ejaculation / drug effects*
  • Electromyography
  • Male
  • Microinjections
  • Naphthalenes / pharmacology
  • Preoptic Area / physiology*
  • Pyrrolidines / pharmacology
  • Rats
  • Rats, Wistar
  • Receptors, Dopamine D3 / agonists*
  • Receptors, Dopamine D3 / antagonists & inhibitors
  • Tetrahydronaphthalenes / pharmacology*

Substances

  • Dopamine Agonists
  • Dopamine Antagonists
  • Naphthalenes
  • Pyrrolidines
  • Receptors, Dopamine D3
  • Tetrahydronaphthalenes
  • nafadotride
  • 7-hydroxy-2-N,N-dipropylaminotetralin