The hypophysiotropic neurotensin-immunoreactive neuronal system of the rat brain

The present study describes the distribution of hypophysiotropic neurotensin-immunoreactive (NTi) perikarya in the rat hypothalamus. After peripheral administration of the retrograde tracer Fluoro-Gold, NT immunoreactivity was demonstrated with fluorescence immunocytochemistry using Texas red-labeled avidin. The results indicate that approximately 70% of all NTi neurons that are connected to the hypophysial portal system are located in the arcuate nucleus. Approximately 30% of these hypophysiotropic NTi neurons reside in the parvocellular subdivisions of the paraventricular nucleus. Our results also show that both the arcuate and the paraventricular nuclei contain NTi perikarya that do not project to the median eminence.