An immuno-electronmicroscopical study comparing vasopressin, oxytocin, substance P and enkephalin containing nerve terminals in the nucleus of the solitary tract of the rat.

Vasopressin, oxytocin, substance P and enkephalin fibers were demonstrated to terminate synaptically in the nucleus of the solitary tract. The detergent Triton X-100 proved to be indispensable for the demonstration of vasopressin and oxytocin while enkephalin and substance P could be visualized very well without it. The differences with respect to morphology between these 4 peptides disappeared when Triton X-100 was used in both groups.