A possible crossed histamine-containing pathway adjacent to the sympathetic system of the rat vas deferens.

Studies using nerve degeneration techniques (ganglionectomy, interganglionic section, postganglionic axotomy, uni- or bilateral hypogastric nerve section and right pelvic ganglionectomy) and fluorometric determinations of histamine and norepinephrine have shown the presence of nervous pathways containing histamine adjacent to the sympathetic system of the rat vas deferens. The findings suggest that these pathways cross between the ganglionic clusters located at the angle formed by the seminal vesicle and the vas deferens. They are not structurally related to the central nervous system by way of the hypogastric or pelvic ganglion. The histamine-containing pathways are independent of the noradrenergic pathways as dissociation between norepinephrine depletion and histamine depletion can be shown under nerve degeneration. The time course of nerve degeneration over a long period after sympathectomy shows a biphasic effect on histamine levels of the vas deferens. The early histamine depletion would be indicative of degeneration of histamine-containing pathways, and the delayed histamine increasing phase has been considered as due to accumulation of mast cells in the degenerating nerve sheaths. A possible role for the histamine-containing pathways in the modulation of sympathetic activity is envisaged.