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Experimental Brain Research

, Volume 88, Issue 2, pp 313–320 | Cite as

A role for 5-hydroxytryptamine in descending inhibition of spinal sexual reflexes

  • L. Marson
  • K. E. McKenna
Regular Papers

Summary

Neurons in the region of the rostral nucleus paragigantocellularis (nPGi) mediate the inhibition of spinal sexual reflexes. Anatomical and pharmacological evidence is presented supporting a role for 5-hydroxytryptamine (5-HT) in this inhibition. Neurons in the rostral nPGi project to the ventral horn in the vicinity of the pudendal motoneurons. A significant number (78% ipsilateral) of these neurons contain 5-HT. Anterograde tracing with Phaseolus leucoagglutinin (PHA-L) confirmed the nPGi projection to pudendal motoneuron and interneuronal areas of the lumbar cord. 5-HT immunoreactive fibers and presumptive terminals surround the pudendal motoneurons. Urethral stimulation, in the anesthetized male rat, elicited penile erections, ejaculation and rhythmic contractions of the perineal muscles, we have used the term coitus reflex to describe this response. Intrathecal injection of 5-HT (4–50 µg) abolished the coitus reflex. Methysergide (1–10 mg/kg i.v.) prevented the 5-HT induced blockade of the coitus reflex. These data support the hypothesis that 5-HT is involved in the descending inhibition of spinal sexual reflexes.

Key words

Serotonin Ventral medulla Sexual reflexes 

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References

  1. Ahlenius S, Larsson K (1991) Opposite effects of 5-methoxy-N,N-di-methyl-tryptamine and 5-hydroxytryptophan on male rat sexual behavior Pharmacol Biochem Behav 38:201–205CrossRefPubMedGoogle Scholar
  2. Ahlenius S, Larsson K, Arvidsson L-E (1989) Effects of stereoselective 5-HT1A agonists on male rat sexual behavior. Pharmacol Biochem Behav 33:691–695Google Scholar
  3. Berendsen HHG, Broekklamp CLE (1987) Drug-induced penile erections in rats; indications of serotonin1B receptor mediation. Eur J Pharmacol 135:279–287CrossRefPubMedGoogle Scholar
  4. Bowker RM, Abbott LC (1990) Quantitative re-evaluation of descending serotonergic and non-serotonergic projections from the medulla of the rodent: evidence for extensive co-existence of serotonin and peptides in the same spinally projecting neurons, but not from the nucleus raphe magnus. Brain Res 512:15–25CrossRefPubMedGoogle Scholar
  5. Caverson MM, Ciriello J (1987) Ventrolateral medullospinal neurons involved in the control of circulation. In: Ciriello J, Calaresu FR, Renaud LP, Polosa C (eds) Organization of the autonomic nervous system: central and peripheral mechanisms. Alan R Liss Inc, New York, pp 227–237Google Scholar
  6. Chung SK, McVary KT, McKenna KE (1988) Sexual reflexes in male and female rats. Neurosci Lett 94:343–384CrossRefPubMedGoogle Scholar
  7. Fernandez-Guasti A, Escalante A, Agmo A (1989) Inhibitory action of various 5-HT1B receptor agonists on rat masculine sexual behavior. Physiol Biochem Behav 34:811–816CrossRefGoogle Scholar
  8. Fischette CT, Nock B, Renner K (1987) Effects of 5,7-dihydroxytryptamine on serotonin 1 and 2 receptors throughout the rat central nervous system using quantitative autoradiography. Brain Res 421:263–279CrossRefPubMedGoogle Scholar
  9. Foreman MM, Hall JL, Love RL (1989) The role of the 5-HT2 receptor in the regulation of sexual performance of male rats. Life Sci 45:1263–1270CrossRefPubMedGoogle Scholar
  10. Gerstenberg TC, Levin RJ, Wagner G (1990) Erection and ejaculation in man. Assessment of the electromyography activity of the bulbocavernosus and ischiocavernosus muscles. Br J Urol 65:395–402PubMedGoogle Scholar
  11. Hillegaart V, Ahlenius S, Larsson K (1989) Effects of local application of 5-HT into the medial and dorsal raphe nuclei on male rat sexual and motor behavior. Behav Brain Res 33:279–286PubMedGoogle Scholar
  12. Holstege JC, Kuypers HGJM (1987) Brainstem projection to lumbar motoneurons in rat. I. An ultrastructural study using autoradiography and the combination of autoradiography and horseradish peroxidase histochemistry. Neuroscience 21:345–367CrossRefPubMedGoogle Scholar
  13. Jackson DA, White SR (1990) Receptor subtypes mediating facilitation by serotonin of excitability of spinal motoneurons. Neuropharmacology 29:787–797CrossRefPubMedGoogle Scholar
  14. Johansson O, Hokfelt T, Pernow B, Jeffcoate SL, White N, Steinbusch HWM, Verhofstad AAJ, Emson PC, Spindel E (1981) Immuno-histochemical support for three putative transmitters in one neuron: coexistence of 5-hydroxytryptamine, substance P and thyrotropin releasing hormone -like immunoreactivity in the medullary neurons projecting to the spinal cord. Neuroscience 6:1857–1881CrossRefPubMedGoogle Scholar
  15. Larsson K, Fuxe K, Everitt BJ, Holmgren BJ, Sodersten P (1978) Sexual behavior in the male rat after intracerebroventricular injection of 5,7-dihydroxytryptamine. Brain Res 141:293–303Google Scholar
  16. Lee RL, Smith DR, Mas M, Davidson JM (1990) Effects of intrathecal administration of 8-OH-DPAT on genital reflexes and mating behavior in male rats. Physiol Behav 47:665–669CrossRefPubMedGoogle Scholar
  17. Maillard C-A, Edwards DA (1990) The lateral paragigantocellularis nucleus: lesions increase copulatory efficiency in male rats. 22nd Annual Conf. on Reproductive Behavior. Atland GA, p 37Google Scholar
  18. Marson L (1989) Evidence for colocalization of substance P and 5-hydroxytryptamine in spinally projecting neurons of the cat medulla oblongata. Neurosci Lett 96:54–59CrossRefPubMedGoogle Scholar
  19. Marson L, Loewy AD (1985) Topographic organization of substance P and monoamine cell bodies in the ventral medulla of the cat. J Auton Nerv Syst 14:271–285CrossRefPubMedGoogle Scholar
  20. Marson L, McKenna KE (1990) The identification of a brainstem site controlling spinal sexual reflexes in male rats. Brain Res 515:303–308CrossRefPubMedGoogle Scholar
  21. Mas M, Zahradnik MA, Martino V, Davidson JM (1985) Stimulation of spinal serotonergic receptors facilitates seminal emission and suppresses penile erectile reflexes. Brain Res 342:128–134Google Scholar
  22. McIntosh T, Barfield RJ (1984) Brain monoaminergic control of male reproductive behavior. I. Serotonin and the post-ejaculatory refractory period. Behav. Brain Res 12:255–265CrossRefPubMedGoogle Scholar
  23. McKenna KE, Nadelhaft I (1986) The organization of the pudendal nerve in the male and female rat. J comp Neurol 248:532–549CrossRefPubMedGoogle Scholar
  24. McKenna KE, Chung SK, McVary KT (1991) A model for the study of sexual reflexes in anesthetized male and female rats. Am J Physiol 261:R1276-R1285PubMedGoogle Scholar
  25. Micevych PE, Coquelin A, Arnold AP (1986) Immunohistochemical distribution of substance P, serotonin and methionine-enkephalin in sexually dimorphic nuclei of the rat lumbar spinal cord. J Comp Neurol 248:235–244CrossRefPubMedGoogle Scholar
  26. Millhorn DE, Hokfelt T, Seroogy K, Oertal W, Verhofstad AAJ, Wu J-Y (1987) Immunohistochemical evidence for colocalization of gamma-aminobutyric acid and serotonin in neurons in the ventral medulla projecting to the spinal cord. Brain Res 410:179–185PubMedGoogle Scholar
  27. Monroe PJ, Smith DJ (1983) Characterization of multiple [3H] 5-hydroxytryptamine binding sites in the rat spinal cord tissue. J Neurochem 41:349–355PubMedGoogle Scholar
  28. Renyi L (1986) The effect of selective 5-hydroxytryptamine uptake inhibitors on 5-methoxy-N,N-dimethyltryptamine-induced ejaculation in the rat. Br J Pharmacol 87:639–648PubMedGoogle Scholar
  29. Sachs BD (1982) Role of striated penile muscles in penile reflexes, copulation, and induction of pregnancy in the rat. J Reprod Fert 66:433–443Google Scholar
  30. Sasek CA, Wessendorf MW, Helke CJ (1990) Evidence for co-existence of thyrotropin-releasing hormone, substance P and serotonin in ventral medullary neurons that project to the intermediolateral cell column in the rat. Neuroscience 35:105–119CrossRefPubMedGoogle Scholar
  31. Schnur SL, Smith ER, Lee RL, Mas M, Davidson JM (1989) A component analysis of the effects of DPAT on male rat sexual behavior Physiol Behav 45:897–901CrossRefPubMedGoogle Scholar
  32. Skagerberg G, Björklund A (1985) Topographic principles or serotonergic and non-serotonergic brainstem neurons in the rat. Neuroscience 15:445–480CrossRefPubMedGoogle Scholar
  33. Steers WD, De Groat WC (1989) Effects ofm-chlorophenylpiperazine on penile and bladder function in rats. Am J Physiol 257:R1441-R1449PubMedGoogle Scholar
  34. Steinbusch HWM (1981) Distribution of serotonin-immunoreactivity in the central nervous system of the rat- cell bodies and terminals. Neuroscience 6:557–618CrossRefPubMedGoogle Scholar
  35. Sternberger LA (1979) Immunocytochemistry, 2nd ed. Wiley and Sons, New YorkGoogle Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • L. Marson
    • 1
  • K. E. McKenna
    • 1
  1. 1.Department PhysiologyNorthwestern University School of MedicineChicagoUSA

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