Learning associated increase in heat shock cognate 70 mRNA and protein expression

• Published in: Neurobiology of learning and memory Vol. 79; no. 2; pp. 142 - 151
• Main Authors: Pizarro, José M., Haro, Luis S., Barea-Rodriguez, Edwin J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.03.2003; Elsevier
• Subjects: Animal; Animals; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Gene Expression; Heat shock cognate 70 (HSC70); Heat shock protein; Hippocampus - metabolism; Hippocampus formation; HSC70 Heat-Shock Proteins; HSP70 Heat-Shock Proteins - biosynthesis; HSP70 Heat-Shock Proteins - genetics; In Situ Hybridization; Learning; Learning and memory; Learning. Memory; Male; Maze Learning - physiology; Memory - physiology; Morris water maze; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Long-Evans; RNA, Messenger - biosynthesis; Spatial Behavior - physiology; Spatial learning; Stress; Stress, Psychological - metabolism; Time Factors; Learning and memory; Hippocampus formation; Morris water maze; Heat shock protein; Heat shock cognate 70 (HSC70); Gene expression; Spatial learning; Stress; Rat; Rodentia; Central nervous system; Spatial ability; Experimental study; Learning; Vertebrata; Mammalia; Acquisition process; Messenger RNA; Animal; Hippocampus; Brain (vertebrata)
• ISSN: 1074-7427; 1095-9564
• DOI: 10.1016/S1074-7427(02)00008-4

The Morris water maze is a task widely used to investigate cellular and molecular changes associated with spatial learning and memory. This task has both spatial and aversive (swimming related stress) components. It is possible that stress may influence cellular modifications observed after learning the Morris water maze spatial task. Heat shock proteins, also known as stress proteins, are up-regulated in response to thermal stress, trauma, or environmental insults. In the rat hippocampus, psychophysiological stress increases the levels of heat shock protein 70 (HSC70). In this study, we investigated whether the expression of the hsc70 gene is modulated in the hippocampus during learning of the Morris water maze task. Five groups of rats were trained in the Morris water maze task for varying amounts of time (either 1, 2, 3, 4, or 5 days). Training consisted of 10 trials/day in which the animals were given 60 s to find a submerged platform. Rats were sacrificed 24 h after their last training trial. Results showed a significant increase in hsc70 mRNA and protein levels in the hippocampal formation after two and three days of training, respectively. The increase in mRNA and protein was associated with learning but not stress because the increase was not observed in the yoked control animals. These findings suggest that cellular and molecular changes can occur independent of stress. Moreover, the results are the first to implicate hsc70 expression in spatial learning.