Catecholamine-containing nerve terminals of the eccrine sweat glands of macaques

Summary A loose network of catecholamine-containing nerves was demonstrated with a fluorescence histochemical method (Falck-Hillarp) in the coiled portion of eccrine sweat glands in the digital pads of macaques after the injection of nialamide and noradrenaline. In the skin of untreated control animals, fluorescent fibers appear only in some of the glands. A systemic administration of reserpine and a local injection of 6-hydroxydopamine (6-OHDA) or 5-hydroxydopamine (5-OHDA) into the digital pad cause a complete disappearance of fluorescent fibers around the glands and blood vessels. Electron micrographs reveal many unmyelinated varicose axon profiles outside the basement membrane of secretory tubules. Most of these profiles contain many small agranular vesicles and a few large dense-cored vesicles (cholinergic terminal), and some have numerous small granular and a few large densecored vesicles (adrenergic terminal).The local injection of 6-OHDA causes various degenerative changes in the adrenergic terminals but the cholinergic ones and the rest of the cellular structure remain intact. The injection of 5-OHDA induces a significant increase of electron-dense granules in the vesicles of adrenergic terminals.The presence of catecholamine and the effects of 6-OHDA and 5-OHDA in the nerve terminals indicate that the innervation of the eccrine sweat glands of macaques consists of cholinergic as well as adrenergic terminals.Publication No. 783 of the Oregon Regional Primate Research Center supported in part by Public Health Service, National Institutes of Health Grant RR 00163 of the Animal Resources Branch, Division of Research Resources.We acknowledge the excellent assistance of Tsutomu Yoshida, Tsuneka zu Fuse, John Ochsner, and Nickolas Roman.