VIP FIBERS IN RAT OPTIC CHIASM AND OPTIC-NERVE ARISING FROM THE HYPOTHALAMUS

This is the first report showing VIP fibers in the optic chiasm and th e optic nerves of intact rats. These fibers form a fan-shaped dorso-me dial bundle in the optic nerves. After colchicine injection into the v itreous body VIP fibers could be followed farther in the optic nerve t oward the eye when compared to intact rats. After removal of eyes (enu cleation) the VIP fiber-bundle became more prominent and VIP immunorea ctive perikarya appeared in the supraoptic and paraventricular nuclei. When five-nine months after the enucleation Phaseolus vulgaris leucoa gglutinin was administered to the paraventricular or supraoptic area, the anterogradely transported tracer was demonstrated in the optic ner ve. These observations suggest the existence of a hypothalamic project ion to the eye, which is, at least in part, VIP immunoreactive. (C) 19 97 Elsevier Science Inc.