SYMPATHETIC REGULATION OF FRUCTOSE SECRETION IN THE SEMINAL-VESICLE OF THE GUINEA-PIG

Fructose secretion of everted guinea-pig seminal vesicles was studied in vitro. Carbachol produced dose dependent increase in fructose secre tion. The effect was blocked by scopolamine but not by hexamethonium, mecamylamine, tetrodotoxin or previous denervation. High concentration s of acetylcholine also increased fructose secretion. This response wa s not augmented by physostigmine. Methoxamine reduced secretion. Metho xamine, terbutaline, clonidine and vasoactive intestinal peptide count eracted carbachol, Field stimulation produced increased secretion that was not blocked by autonomic drugs, tetrodotoxin or previous denervat ion. Stimulation of the hypogastric nerve produced frequency dependent increase in fructose secretion. The effect was blocked by tetrodotoxi n and scopolamine but not enhanced by physostigmine. If the hypogastri c nerve was stimulated close to the seminal vesicle the response was u naffected by hexamethonium but proximal stimulation was blocked. After chronic proximal denervation of the hypogastric nerve, stimulation cl ose to the seminal vesicle produced enhanced response. Destruction of the peripheral ganglia at the base of the seminal vesicle abolished th e response. Sections showed that most secretory nerves enter the organ at its base. Phentolamine or yohimbine but not prazosine or propranol ol or guanethidine enhanced the secretory response to distal hypogatri c nerve stimulation. Tyramine counteracted the response but after rese rpinization it was enhanced by tyramine. It is concluded that the secr etory cells of the guinea-pig seminal vesicle have a sympathetic secre tomotor innervation by short cholinergic neurones with a preganglionic supply via the hypogastric nerve. Inhibitory alpha(1) and beta(1)-adr enoreceptors are present on the cells but neurogenic adrenergic inhibi tion of the secretion is essentially prejunctional and due to activati on of inhibitory alpha 1-receptors on the secretomotor nerves.