title: Neurotensin projections to subfornical organ from arcuate nucleus.
abstract: Two series of experiments were done in the rat to investigate whether neurons in arcuate nucleus of the hypothalamus (Arc) containing neurotensin (NT)-like immunoreactivity projected to subfornical organ (SFO). In the first series, the anterograde tract-tracer Phaseolus vulgaris leucoagglutinin (PHA-L) was microiontrophoresed into the region of Arc that contains NT neurons. After a 9-12 day survival period the animals were sacrificed and forebrain sections that contained SFO were processed for combined PHA-L and NT immunoreactivity. In the second series of experiments, unilateral or bilateral electrolytic lesions of Arc were made and after a 10-17 day survival period SFO was examined to determine the relative contribution of NT Arc neurons to NT immunoreactivity within SFO. PHA-L labelled fibers with terminal-like boutons were found in SFO primarily on the side ipsilateral to the site of injection. A small number of the PHA-L labelled fibers in the lateral aspect of SFO was also immunoreactive to NT. Unilateral lesions reduced, whereas bilateral lesions of Arc eliminated most of the NT-like immunoreactivity within SFO. These data demonstrate the existence of a direct pathway from Arc to SFO that contains the putative neurotransmitter NT. These results suggest that this pathway may function in the modulation of neural and/or humoral events related to cardiovascular regulation and body fluid homeostasis by influencing the activity of SFO neurons.
authors.affiliation: Department of Physiology, University of Western Ontario, London, Canada.
authors.forename: M P
authors.initials: MP
authors.lastname: Rosas-Arellano
authors.forename: L P
authors.initials: LP
authors.lastname: Solano-Flores
authors.forename: J
authors.initials: J
authors.lastname: Ciriello
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000737:chemistry* / Q000166:cytology; D007150:Immunohistochemistry; D007478:Iontophoresis; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009496:Neurotensin / Q000032:analysis*; D010835:Phytohemagglutinins; D051381:Rats; D017208:Rats, Wistar; D013356:Subfornical Organ / Q000502:physiology*
chemical_list: D010835:Phytohemagglutinins; C100156:leukoagglutinins, plants; D009496:Neurotensin