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Etude de l’erection chez le rat: un nouveau modele physiologique

Penile erection in the rat: A new physiological model

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Abstract

Penile erection is a muscular and vascular event mediated by the autonomic nervous system. The neurophysiology of erection remains poorly understood and controversial, requiring a suitable model for in-vitro studies of erectile function. Such a model, based in the rat whose penile innervation is very similar to man, is described here. The first study using this model considers the influence of systemic blodd pressure (BP) on penile erection. In 33 anaesthetized rats the pelvic and cavernosal nerves were identified and dissected. Supra maximal electrical stimulation was delivered over 1 minute by a train of 1 ms pulses onto the pelvic nerve (10 V, 15 Hz) or the cavernosal nerve (6 V, 10 Hz). Systemic blood pressure and intracavernosal pressure (ICP) were monitored and stored on a computer. As in previous animal models (dog, monkey), four phases of the cavernosal response to neural electrical stimulation were observed: latency, tumescence, full erection, and détumescence. In all rats electrical stimulation of either the pelvic or cavernosal nerves significantly increased intracavernosal pressure. Complete erectile response (rigidity and unfolding of the penis) was only seen with intracavernosal pressures > 95 mm Hg. Intracavernosal pressure increased proportionally with blood preessure during the full erection phase according to the equation ICP=0.94 BP − 31 mm Hg (r=0.94 BP − 31 mm Hg (r=0.94) for electrical stimulation of the cavernosal nerve, or the alternative aquation ICP=0.76 BP − 21 mm Hg (r=0.73) for electrical stimulation of the pelvic nerve. The rat is a readily available model for the study of erection and present obvious advantages over existing models such as the dog, cat and monkey. Cavernosal repsonse to neural stimulation was closely related to arterial blood pressure and the two linear equations presented above should be considered further in studies modifying autonomic neurotransmission as well as in relation to the effects of pharmacological compounds with vasomotor actions on erectile function.

Resume

Les mécanismes locaux responsables de l’érection sont sous contrôle neurohumoral. L’exploration de ce contrôle mal connu nécessite un modèle d’étude in vivo de la fonction érectile. Nous avons choisi le rat comme modèle, l’innervation pénienne de cet animal étant très proche de celle de l’homme. Chez 33 rats anesthésiés la réponse érectile à la stimulation électrique du nerf pelvien (NP) ou du nerf caverneux (NC) a été étudiée par la mesure de la pression intracaverneuse (PIC), la pression artérielle était également enregistrée. Chez tous les rats, la stimulation du NP ou du NC a provoqué une augmentation de PIC. La réponse caverneuse à l’électrostimulation présentait 4 phases: latence, tumescence, érection ou tumescence complètes et détumescence. Pendant l’érection la PIC était proportionnelle à la PA suivant une étroite corrélation. La réponse érectile des corps caverneux à la stimulation du NP ou du NC chez le rat était superposable à celle observée chez le chien ou le singe dans les mêmes conditions expérimentales. La relation liant la PIC et la PA durant l’érection doit être considérée lors de l’étude de l’effet sur l’érection de substances pharmacologiques modifiant la vasomotricité générale. Ainsi nous avons validé un modèle d’érection chez le rat. Les avantages évidents du rat sur les gros animaux devraient le faire choisir par les expérimentateurs futurs.

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Correspondence to F. Giuliano.

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Giuliano, F., Bernabé, J., Benoit, G. et al. Etude de l’erection chez le rat: un nouveau modele physiologique. Androl. 2, 25–27 (1992) doi:10.1007/BF03034591

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Key words

  • penile erection
  • rat
  • electrostimulation
  • neurophysiology
  • hemodynamics

Mots clés

  • Erection
  • rat
  • électrostimulation
  • neurophysiologie
  • hemodynamique