[Physiology and pharmacology of ejaculation]

Abstract

Ejaculation requires an interplay of peripheral actors comprising, among others, smooth and skeletal fibers, glandular and endothelial cells. These actors are driven by vegetative and somatic innervations, deriving essentially from the spinal cord, in turn controlled by cerebral structures and endocrine factors, mostly steroids; These controls require sensitive afferences and command two steps, emission under autonomic control, and ejaculation per se which further involves somatic motoneurons. This review first describes the peripheral innervation of the part of the genital tract concerned in ejaculation, in which the sympathetic component is predominant and releases noradrenalin and neuropeptides; however parasympathetic and somatic components also play a role. At the spinal level, control circuits are organized into networks influenced by spinal structures, which have been discovered through selective lesions or stimulations, as well as by retrograde trans-synaptic tracing with neurotropic viruses. Among these structures, the median preoptic area and the hypothalamic paraventricular nucleus are major regulation sites. On the other hand, serotoninergic and also dopaminergic and adrenergic systems are implicated as well in the command of ejaculation; the latter constitute priviledged targets for a pharmacological treatment of dysfunctions.