Placement in a novel environment induces Fos-like immunoreactivity in supramammillary cells projecting to the hippocampus and midbrain

• Published in: Brain research 1998-04, Vol.789 (2), p.331-334
• Main Authors: Wirtshafter, David, Stratford, Thomas R, Shim, Insop
• Format: Article
• Language: English
• Subjects: Anatomical correlates of behavior; Animals; Arousal; Behavioral psychophysiology; Biological and medical sciences; c- fos; Double labeling; Environment; Fundamental and applied biological sciences. Psychology; Hippocampus; Hippocampus - physiopathology; Hypothalamus; Immediate early gene; Immunohistochemistry; Male; Mammillary Bodies - metabolism; Mammillary Bodies - pathology; Mammillary Bodies - physiopathology; Mesencephalon - physiopathology; Neurons - cytology; Neurons - metabolism; Neurons - physiology; Proto-Oncogene Proteins c-fos - metabolism; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Raphe nuclei; Raphe Nuclei - physiopathology; Rats; Rats, Sprague-Dawley; Stress; Stress, Physiological - physiopathology; Supramammillary region; Synaptic Transmission - physiology
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(97)01555-2

Injections of fluorescent retrograde tracers into either the hippocampal formation or the midbrain raphe nuclei resulted in retrograde labeling of many cells in the supramammillary region of the hypothalamus. Double labeling studies indicated that these two projections originate from different populations of supramammillary cells. Expression of the proto-oncoprotein Fos could be induced in some retrogradely labeled cells by placing rats in a novel open field before sacrifice. Although seen in both cell types, Fos-like immunoreactivity was significantly more common in supramammillary cells projecting to the hippocampus than in those projecting to the midbrain. These findings suggest that the supramammillary region may contain several populations of neurons which are differentially responsive to certain behavioral manipulations.