5-hydroxytryptamine levels in peripheral organs of immunosympathectomized rats

Littermate Sprague-Dawley rats were immunosympathectomized by the daily injection of Nerve Growth Factor (NGF)-antiserum for 6 days after birth. The 5-hydroxytryptamine concentrations of peripheral tissues, spinal cord and brain stem (medulla, pons, mesencephalon and diencephalon) were measured spectrophotofluorometrically by the method of Bogdanski etal. ‡ ‡ F. Bogdanski, A. Pletcher, B. B. Brodie and S. Udenfriend, J. Pharmac. 117, 82 (1956). In immunosympathectomized rats the 5-hydroxytryptamine levels of the submaxillary glands, hearts and cecum were significantly increased. Statistically nonsignificant elevations were also noted in the lungs, upper intestinal tract, liver and uterus. The submaxillary glands of immunosympathectomized rats were significantly smaller than those of control littermates. The administration of JB-516 (Catron, β-phenylisopropylhydrazine) or 5-hydroxytryptophan did not present evidence to explain the elevated 5-hydroxytryptamine levels in some of the peripheral tissues from immunosympathectomized rats. It is not known whether the rise of the 5-hydroxytryptamine levels in some peripheral tissues from immunosympathectomized rats was a direct result of the NGF-antiserum administration or whether it was due to the fact that these tissues are largely devoid of sympathetic innervation. The most marked and consistent elevation of 5-hydroxytryptamine occurred in those tissues (submaxillary glands and heart) which are nearly completely sympathectomized by the NGF-antiserum administration.