Transcription factor expression, RNA synthesis and NADPH-diaphorase across the rat brain and exposure to spatial novelty

• Published in: Behavioural brain research Vol. 184; no. 1; pp. 91 - 100
• Main Authors: Romanelli, P., Di Matteo, L., Cobellis, G., Varriale, B., Menegazzi, M., Gironi Carnevale, U.A., Ruocco, L.A., Sadile, A.G.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 22-11-2007; Elsevier Science
• Subjects: 3H-Uridine incorporation; Analysis of Variance; Animals; Autoradiography - methods; Behavior, Animal; Behavioral psychophysiology; Behavioural habituation; Biological and medical sciences; Brain - metabolism; Brain ribonucleic acid; Emotions - physiology; Exploratory Behavior - physiology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; Male; Maze Learning; Model systems; NADPH Dehydrogenase - metabolism; Nitric oxide synthase; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Sprague-Dawley; RNA - metabolism; Spatial Behavior - physiology; Time Factors; Transcription Factors - genetics; Transcription Factors - metabolism; Tritium - metabolism; Uridine - metabolism; 3H-Uridine incorporation; Model systems; Nitric oxide synthase; Behavioural habituation; Brain ribonucleic acid; Rat; Enzyme; Rodentia; Central nervous system; Exposure; Gene expression; NADPH dehydrogenase; Nitric-oxide synthase; Encephalon; Habituation; Vertebrata; Mammalia; Animal; Uridine; Models; Oxidoreductases; Behavior; Transcription factor; Pyrimidine nucleoside
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/j.bbr.2007.06.021

The molecular hypothesis of learning and memory processes is based on changes in synaptic weights in neural networks. Aim of this study was to map neural traces of exposure to a spatial novelty were mapped by (i) the transcription factors (TFs)
c-fos,
c-jun and
jun-B using Northern blot and immunocytochemistry (ICC), (ii) RNA synthesis by
3H-uridine autoradiography and RNA level, (iii) NADPH-diaphorase (NADPH-d) expression by histochemistry. Thus, adult male albino rats were exposed to a Làt-maze and sacrificed at different times. Non-exposed rats served as controls. The latter showed a low constitutive expression of TF, RNA synthesis and NADPH-d across the brain. Northern blots showed a three-fold increase in TFs in exposed versus non-exposed rats in the cerebral cortex. ICC showed in exposed rats several TFs positive cells in the granular and pyramidal layers of the hippocampus and later in all layers of the somatosensory cortex, in the granular layer of the cerebellar cortex. The TF-positivity was stronger in rats exposed for the first time, and was time and NMDA-dependent. Autoradiography for RNA synthesis showed positive cells in the ependyma, hippocampus and cerebellum 6
h after testing, and in the somatosensory cortex 24
h later. In addition, exposure to novelty induced NADPH-d in the dorsal hippocampus, the caudate-putamen, all the layers of the somatosensory cortex. and the cerebellum. The positivity was absent immediately after exposure, appeared within 2
h and disappeared 24
h later. A strong neuronal discharge by the convulsant pentylenetetrazol, strongly induced TFs but not din not affect NADPH-d 2
h later. Thus, data suggest that the processing of spatial and emotional components of experience activates neural networks across different organization levels of the CNS.