NERVE GROWTH-FACTOR TREATMENT OF ADULT-RATS SELECTIVELY ENHANCES INNERVATION OF URINOGENITAL TRACT RATHER THAN VASCULAR SMOOTH-MUSCLE

Following treatment of adult rats with nerve growth factor (0.5 mg/rat , three times a week for 3 weeks), the innervation of cardiovascular a nd urinogenital tract smooth muscle was investigated using immunoassay and immunohistochemical techniques. Substance P and calcitonin gene r elated peptide levels were increased in the vas deferens, but not in t he atria or femoral artery. Neuropeptide Y and vasoactive intestinal p olypeptide levels were unchanged. In penile tissues, there was a marke d increase in the density of substance P-, calcitonin gene related pep tide-, neuropeptide Y-, tyrosine hydroxylase- and vasoactive intestina l polypeptide-containing nerves innervating the urethra and in SP-cont aining nerves in the tunica with little change in the innervation of t he deep dorsal vein and artery and corpus cavernosum. In the bladder, there was increased innervation of the detrusor by neuropeptide Y- and vasoactive intestinal polypeptide-containing nerves, but a decrease i n innervation by substance P-containing nerves in the trigone. There w ere no changes in the density of innervation of the femoral artery aft er nerve growth factor treatment. Thus, in the mature rat, sensory and sympathetic nerves innervating urinogenital tract smooth muscle appea r to be more responsive to exogenous nerve growth factor than those in nervating cardiovascular smooth muscle. This may reflect an ongoing re quirement of plasticity of innervation in the urinogenital tract of th e sexually mature animal.