ABSTRACT
The distributions of neurotensin(NT) and substance P(SP) in the arcuate nucleus of rat hypothalamus have been studied by means of double labeled pre-embedding immunoelectron microscopic technique. It was observed that there were SP- and NT-containing dendrites, perikarya and axons in the arcuate nucleus. SP- and NT-containing dendrites and axons received asymmetric afferent synapses from immunonegative axons. SP-positive axonal terminals established symmetric axo-somatic and axo-dendritic synapses with immunonegative perikarya and dendrites as well as symmetric axo-somatic synapses with NT-positive perikarya. The results of this study directly indicate for the first time that the NT-ergic neurons in rat arcuate nucleus receive innervation from SP-ergic neurons, and provided an ultrastructural evidence for the synaptic regulation of the neuroendocrine of the hypothalamus.
ABSTRACT
In order to study the bifurcate projections of midbrain periaqueductal gray and nucleus raphe dorsalis to nucleus accumbens and nucleus raphe magnus, the fluorescence double-labeled method was used in the present study. Bisbenzimide (Bb) and propidium iodide (PI) were injected into nucleus raphe magnus and unilateral nucleus accumbens stereotaxically according to the time period necessary for their axonal transport. The percentages of double-labeled neurons were 21％; PI single labeled neurons were 32％; Bb single labeled neurons were 47％. Most of the labeled neurons were located in the middle and caudal parts of periaqueductal gray and the nucleus raphe dorsalis, and most were medium sized and fusiform and triangular in shape.