Hippocampal expression of the orphan nuclear receptor gene hzf-3/nurr1 during spatial discrimination learning.
The immediate-early gene hzf-3, also known as nurr1, is a member of the inducible orphan nuclear receptor family and is one candidate in the search for genes associated with learning and memory processes. Here we report that acquisition of a spatial food search task is accompanied by elevated levels of hzf-3 mRNA in the hippocampus. Adult male Long-Evans rats were handled, food-restricted, and allowed to habituate to the maze prior to training. During acquisition, rats were given one training session per day for 5 days. Each training session consisted of five trials in which animals searched the maze for food located in 4 of 16 holes in the floor of the maze. Training resulted in spatial acquisition of the task. Northern blot analysis showed significant increases in hippocampal hzf-3 mRNA 3 h after training in the maze. Next, brains were obtained from Naive, Habituated, Day 1, Day 3, and Day 5 animals and processed for in situ hybridization. The results showed significant increases of hzf-3 mRNA in CA1 and CA3 subregions of the dorsal hippocampus during acquisition of the task. We conclude that expression of the hzf-3 gene in the brain is associated with long-term spatial memory processes. The present results are the first to implicate an orphan nuclear receptor in long-term information storage in the hippocampus.
Department of Biology, University of Puerto Rico, San Juan, Puerto Rico 00931-3360, USA. spena@upracd.upr.clu.edu
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Peña de Ortiz
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Maldonado-Vlaar
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Carrasquillo
D000818:Animals; D015152:Blotting, Northern; D004268:DNA-Binding Proteins; D004193:Discrimination Learning / Q000502:physiology*; D015870:Gene Expression; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics*; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013028:Space Perception / Q000502:physiology; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics*
D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; C539884:Nr4a2 protein, rat; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D012333:RNA, Messenger; D014157:Transcription Factors