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α-Adrenergic agents modulate the activity of the spinal pattern generator for ejaculation

International Journal of Impotence Research volume 18, pages 32–38 (2006)Cite this article

Abstract

Spinal cord transection at a thoracic level activates fictive ejaculation (FE) in the male rat. It has earlier been demonstrated that fictive motor patterns may be activated by pharmacological means and that the noradrenergic system seems to be particularly efficient in triggering locomotor fictive patterns in spinal animals. In the present study, the hypothesis was tested that the spinal noradrenergic system participates in the activation of the spinal generator for ejaculation (SGE). To this aim, the effect of the adrenergic agents, methoxamine, prazosin, clonidine, and yohimbine, upon FE was evaluated in spinal male rats using electromyographic techniques. The results obtained show that ejaculatory rhythmic patterns, accompanied by the expulsion of urethral contents and phasic penile movements, can be elicited by the intravenous (i.v.) injection of methoxamine or yohimbine. These drug-induced motor sequences appear superimposed to the intrinsic ejaculatory spinal rhythm. By contrast, i.v. injection of prazosin or clonidine blocked the expression of the spontaneous ejaculatory rhythmic pattern without inducing any other genital response. These data suggest that an increased noradrenergic tone, either by blockade of presynaptic α2-adrenoceptors or by stimulation of postsynaptic α1-adrenoceptors, results in the activation of the SGE. Present findings provide the evidence that the SGE might be importantly influenced by the noradrenergic system, which exerts a facilitatory control on the expression of the genital motor pattern of ejaculation.

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Acknowledgements

We thank Mrs Angeles Ceja for technical assistance and animal caring.

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Authors and Affiliations

  1. Laboratorio de Comportamiento Reproductivo, Escuela de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tlaxcala, Tlaxcala, México

    M Carro-Juárez

  2. Departamento de Farmacobiología, CINVESTAV, IPN, Tlalpan, México

    G Rodríguez-Manzo

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  1. M Carro-Juárez
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  2. G Rodríguez-Manzo
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Correspondence to M Carro-Juárez.

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Carro-Juárez, M., Rodríguez-Manzo, G. α-Adrenergic agents modulate the activity of the spinal pattern generator for ejaculation. Int J Impot Res 18, 32–38 (2006). https://doi.org/10.1038/sj.ijir.3901393

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