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Time-dependent expression of Arc and zif268 after acquisition of fear conditioning.

Lonergan ME, Gafford GM, Jarome TJ, Helmstetter FJ - Neural Plast. (2010)

Bottom Line: Arc, an effector immediate early gene, and zif268, a regulatory transcription factor, have been implicated in synaptic plasticity underlying learning and memory.The timing of hippocampal Arc and zif268 expression coincides with the critical period for protein synthesis-dependent memory consolidation following fear conditioning.These findings suggest that altered Arc and zif268 expression are related to neural plasticity during the formation of fear memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Wisconsin-Milwaukee, 2441 E. Hartford Avenue, Milwaukee, WI 53211, USA.

ABSTRACT
Memory consolidation requires transcription and translation of new protein. Arc, an effector immediate early gene, and zif268, a regulatory transcription factor, have been implicated in synaptic plasticity underlying learning and memory. This study explored the temporal expression profiles of these proteins in the rat hippocampus following fear conditioning. We observed a time-dependent increase of Arc protein in the dorsal hippocampus 30-to-90-minute post training, returning to basal levels at 4 h. Zif268 protein levels, however, gradually increased at 30-minute post training before peaking in expression at 60 minute. The timing of hippocampal Arc and zif268 expression coincides with the critical period for protein synthesis-dependent memory consolidation following fear conditioning. However, the expression of Arc protein appears to be driven by context exploration, whereas, zif268 expression may be more specifically related to associative learning. These findings suggest that altered Arc and zif268 expression are related to neural plasticity during the formation of fear memory.

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Expression of zif268 protein in the dorsal hippocampus following fear conditioning.  (a) zif268 protein expression exhibits a noticeable increase at 30–60 min post-training.  Statistical analysis revealed that protein levels are not different from HC after 60 min.  Bar graph represents the group means + SEM.  Representative western blot images are presented for each group directly below the corresponding graph.  Significant differences from HC controls are denoted with asterisks: *P < .05, **P < .01.  (b) Brightfield photomicrograph (2x magnification) of the dorsal hippocampus.  The boxed area indicates the region of CA1 depicted in the immunofluorescence images of (c) and (d) (10x magnification).  (c) Basal expression of zif268 protein in the CA1 of home cage animal.  (d) zif268 protein expression is increased in CA1 neurons 30 min after fear conditioning.  (e), (f) Higher magnification photomicrographs (20x magnification) of the boxed regions from (c) and (d), respectively.
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fig3: Expression of zif268 protein in the dorsal hippocampus following fear conditioning. (a) zif268 protein expression exhibits a noticeable increase at 30–60 min post-training. Statistical analysis revealed that protein levels are not different from HC after 60 min. Bar graph represents the group means + SEM. Representative western blot images are presented for each group directly below the corresponding graph. Significant differences from HC controls are denoted with asterisks: *P < .05, **P < .01. (b) Brightfield photomicrograph (2x magnification) of the dorsal hippocampus. The boxed area indicates the region of CA1 depicted in the immunofluorescence images of (c) and (d) (10x magnification). (c) Basal expression of zif268 protein in the CA1 of home cage animal. (d) zif268 protein expression is increased in CA1 neurons 30 min after fear conditioning. (e), (f) Higher magnification photomicrographs (20x magnification) of the boxed regions from (c) and (d), respectively.

Mentions: A different temporal pattern was seen in the protein expression profile for zif268, with a single peak evident at 60 min post training (F(7,72) = 3.228, P < .01, see Figure 3(a)). LSD post-hoc comparisons revealed that zif268 protein is significantly increased at 60 min when compared to HC animals (MD = 55.2942, P < .01). In fact, the protein level for zif268 measured at 60 min is significantly higher than all other time points (90 min: MD = 60.6474, P < .01; 4 hr: MD = 71.1209, P < .01; 8 hr: MD = 86.4159, P < .01; 12 hr: MD = 86.9798, P < .01; 24 hr: MD = 69.0759, P < .01) with the exception of 30 min (MD = 32.7638, P > .05).


Time-dependent expression of Arc and zif268 after acquisition of fear conditioning.

Lonergan ME, Gafford GM, Jarome TJ, Helmstetter FJ - Neural Plast. (2010)

Expression of zif268 protein in the dorsal hippocampus following fear conditioning.  (a) zif268 protein expression exhibits a noticeable increase at 30–60 min post-training.  Statistical analysis revealed that protein levels are not different from HC after 60 min.  Bar graph represents the group means + SEM.  Representative western blot images are presented for each group directly below the corresponding graph.  Significant differences from HC controls are denoted with asterisks: *P < .05, **P < .01.  (b) Brightfield photomicrograph (2x magnification) of the dorsal hippocampus.  The boxed area indicates the region of CA1 depicted in the immunofluorescence images of (c) and (d) (10x magnification).  (c) Basal expression of zif268 protein in the CA1 of home cage animal.  (d) zif268 protein expression is increased in CA1 neurons 30 min after fear conditioning.  (e), (f) Higher magnification photomicrographs (20x magnification) of the boxed regions from (c) and (d), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig3: Expression of zif268 protein in the dorsal hippocampus following fear conditioning. (a) zif268 protein expression exhibits a noticeable increase at 30–60 min post-training. Statistical analysis revealed that protein levels are not different from HC after 60 min. Bar graph represents the group means + SEM. Representative western blot images are presented for each group directly below the corresponding graph. Significant differences from HC controls are denoted with asterisks: *P < .05, **P < .01. (b) Brightfield photomicrograph (2x magnification) of the dorsal hippocampus. The boxed area indicates the region of CA1 depicted in the immunofluorescence images of (c) and (d) (10x magnification). (c) Basal expression of zif268 protein in the CA1 of home cage animal. (d) zif268 protein expression is increased in CA1 neurons 30 min after fear conditioning. (e), (f) Higher magnification photomicrographs (20x magnification) of the boxed regions from (c) and (d), respectively.
Mentions: A different temporal pattern was seen in the protein expression profile for zif268, with a single peak evident at 60 min post training (F(7,72) = 3.228, P < .01, see Figure 3(a)). LSD post-hoc comparisons revealed that zif268 protein is significantly increased at 60 min when compared to HC animals (MD = 55.2942, P < .01). In fact, the protein level for zif268 measured at 60 min is significantly higher than all other time points (90 min: MD = 60.6474, P < .01; 4 hr: MD = 71.1209, P < .01; 8 hr: MD = 86.4159, P < .01; 12 hr: MD = 86.9798, P < .01; 24 hr: MD = 69.0759, P < .01) with the exception of 30 min (MD = 32.7638, P > .05).

Bottom Line: Arc, an effector immediate early gene, and zif268, a regulatory transcription factor, have been implicated in synaptic plasticity underlying learning and memory.The timing of hippocampal Arc and zif268 expression coincides with the critical period for protein synthesis-dependent memory consolidation following fear conditioning.These findings suggest that altered Arc and zif268 expression are related to neural plasticity during the formation of fear memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Wisconsin-Milwaukee, 2441 E. Hartford Avenue, Milwaukee, WI 53211, USA.

ABSTRACT
Memory consolidation requires transcription and translation of new protein. Arc, an effector immediate early gene, and zif268, a regulatory transcription factor, have been implicated in synaptic plasticity underlying learning and memory. This study explored the temporal expression profiles of these proteins in the rat hippocampus following fear conditioning. We observed a time-dependent increase of Arc protein in the dorsal hippocampus 30-to-90-minute post training, returning to basal levels at 4 h. Zif268 protein levels, however, gradually increased at 30-minute post training before peaking in expression at 60 minute. The timing of hippocampal Arc and zif268 expression coincides with the critical period for protein synthesis-dependent memory consolidation following fear conditioning. However, the expression of Arc protein appears to be driven by context exploration, whereas, zif268 expression may be more specifically related to associative learning. These findings suggest that altered Arc and zif268 expression are related to neural plasticity during the formation of fear memory.

Show MeSH