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Role of Peripheral Innervation in P-Chloroamphetamine–Induced Ejaculation in Anesthetized Rats

STEPHANE DROUPY

PIERRE DENYS

FRANÇOIS GIULIANO^*,

From the ^* Pelvipharm Laboratories, Campus CNRS, Gif-sur-Yvette, France; Groupe de Recherche en Urologie, UPRES, Medical University of Paris-South, Le Kremlin-Bicêtre Cedex, France; and Neuro-Urology Unit, Department of Neurological Rehabilitation, Raymond Poincaré Hospital, Garches, France.

Correspondence to: Dr François Giuliano, Neuro-Urology Unit, Department of Neurological Rehabilitation, Raymond Poincaré Hospital, 104 bd Raymond Poincaré, 92380 Garches, France (e-mail: giuliano{at}cyber-sante.org).

The occurrence of ejaculation, which consists of 2 distinct phases (emission and expulsion), requires a tight coordination of peripheral autonomic and somatic nerves. However, some aspects of the mechanism of ejaculation are not clearly defined. To clarify this issue, we used the p-chloroamphetamine (PCA)-induced ejaculation model in anesthetized rats and investigated the effects of selective peripheral nerves lesions on seminal vesicle and bulbospongiosus (BS) muscle activities as representing physiological markers of emission and expulsion phases, respectively. In intact rats, ejaculation induced with PCA (intraperitoneal 5 mg/kg) correlated with coordinated increases in seminal vesicle pressure (SVP) and BS electromyographic activity. PCA-induced ejaculation was still observed in rats with bilateral lesion of hypogastric nerves (HNx), lumbar paravertebral sympathetic chain (LSCx), or dorsal nerves of the penis (DNPx). Conversely, bilateral section of pelvic nerves (PNx) or L6-S1 dorsal roots (DRx) abolished PCA-induced ejaculation. The amplitude of SVP increases induced by PCA was reduced in PNx, HNx, and LSCx rats, whereas it was unchanged in DRx and DNPx rats. The time interval between SVP increases and BS muscle contractions induced by PCA was comparable in the different neural lesion groups. In conclusion, PCA initiates both emission and expulsion independently from each other. In this model, afferents conveyed by the pelvic nerves appear to be unnecessary for occurrence of BS muscle contractions but are essential for a complete ejaculatory response.

     Key words: Seminal vesicle, bulbospongiosus muscles, sympathetic nerves, parasympathetic nerves, sensory afferents