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EphrinA4 mimetic peptide targeted to EphA binding site impairs the formation of long-term fear memory in lateral amygdala.

Dines M, Lamprecht R - Transl Psychiatry (2014)

Bottom Line: Acute systemic administration of pep-ephrinA4 1 h after training also impaired long-term fear conditioning memory formation.These results demonstrate that ephrinA4 binding sites in LA are essential for long-term fear memory formation.Moreover, our research shows that ephrinA4 binding sites may serve as a target for pharmacological treatment of fear and anxiety disorders.

View Article: PubMed Central - PubMed

Affiliation: Sagol Department of Neurobiology, University of Haifa, Haifa, Israel.

ABSTRACT
Fear conditioning leads to long-term fear memory formation and is a model for studying fear-related psychopathologies conditions such as phobias and posttraumatic stress disorder. Long-term fear memory formation is believed to involve alterations of synaptic efficacy mediated by changes in synaptic transmission and morphology in lateral amygdala (LA). EphrinA4 and its cognate Eph receptors are intimately involved in regulating neuronal morphogenesis, synaptic transmission and plasticity. To assess possible roles of ephrinA4 in fear memory formation we designed and used a specific inhibitory ephrinA4 mimetic peptide (pep-ephrinA4) targeted to EphA binding site. We show that this peptide, composed of the ephrinA4 binding domain, interacts with EphA4 and inhibits ephrinA4-induced phosphorylation of EphA4. Microinjection of the pep-ephrinA4 into rat LA 30 min before training impaired long- but not short-term fear conditioning memory. Microinjection of a control peptide derived from a nonbinding E helix site of ephrinA4, that does not interact with EphA, had no effect on fear memory formation. Microinjection of pep-ephrinA4 into areas adjacent to the amygdala had no effect on fear memory. Acute systemic administration of pep-ephrinA4 1 h after training also impaired long-term fear conditioning memory formation. These results demonstrate that ephrinA4 binding sites in LA are essential for long-term fear memory formation. Moreover, our research shows that ephrinA4 binding sites may serve as a target for pharmacological treatment of fear and anxiety disorders.

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Inhibitory ephrinA4 mimetic peptide in the lateral amygdala (LA) impairs long-term fear memory (LTM) formation. (a) Pep-ephrinA4 (0.5 μl of 10 μg per μl; n=9), pep-control (0.5 μl of 10 μg per μl; n=5) or saline (n=7) were microinjected into rat LA 30 min before fear conditioning. Long-term memory was tested 24 h after training. Animals injected with pep-ephrinA4 were significantly impaired in fear memory (F(3)=6.428, P<0.003) when compared with pep-control (P<0.005), saline (P<0.02) or pep-ephrinA4 injected into areas surrounding the LA (P<0.03, n=11). The control microinjected groups (saline, control peptide and misplaced pep-ephrinA4) were not different from each other (P>0.5). (b) Cannula placements within the boundaries of lateral and basal amygdala (LBA) of pep-ephrinA4-, saline- and pep-control-microinjected rats. (c) Cannula placements of pep-ephrinA4 microinjected in areas near LA. CS, conditioned stimulus.
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fig2: Inhibitory ephrinA4 mimetic peptide in the lateral amygdala (LA) impairs long-term fear memory (LTM) formation. (a) Pep-ephrinA4 (0.5 μl of 10 μg per μl; n=9), pep-control (0.5 μl of 10 μg per μl; n=5) or saline (n=7) were microinjected into rat LA 30 min before fear conditioning. Long-term memory was tested 24 h after training. Animals injected with pep-ephrinA4 were significantly impaired in fear memory (F(3)=6.428, P<0.003) when compared with pep-control (P<0.005), saline (P<0.02) or pep-ephrinA4 injected into areas surrounding the LA (P<0.03, n=11). The control microinjected groups (saline, control peptide and misplaced pep-ephrinA4) were not different from each other (P>0.5). (b) Cannula placements within the boundaries of lateral and basal amygdala (LBA) of pep-ephrinA4-, saline- and pep-control-microinjected rats. (c) Cannula placements of pep-ephrinA4 microinjected in areas near LA. CS, conditioned stimulus.

Mentions: We hypothesize that ephrinA4 interaction with EphA is essential for fear conditioning memory formation in LA and that microinjection of the inhibitory pep-ephrinA4 peptide into this brain area will interfere with the process of creating long-term fear memory. To test this hypothesis we compared the effects of the pep-ephrinA4 to that of the pep-control, that do not interact with EphA, on long-term fear memory formation in LA. We microinjected the pep-ephrinA4, pep-control or saline into the LA 30 min before fear conditioning. Rats with cannula tips at or within the boundaries of lateral and basal amygdala (LBA) were included in the data analysis (Figure 2). Long-term conditioned fear memory was assessed by measuring freezing responses elicited by the CS without the unconditioned stimulus 24 h after conditioning. Figure 2a shows that rats microinjected with pep-ephrinA4 froze significantly less (F(3)=6.428, P<0.003) than animals injected with saline (P<0.02), control peptide (P<0.005) or animals injected with pep-ephrinA4 in areas adjacent to the LA (P<0.03), showing that pep-ephrinA4-treated animals are impaired in long-term fear memory. The group × tone trial interaction did not differ significantly (F(8.481)=1.487, P>0.17), indicating that pep-ephrinA4 did not alter the rate of fear reduction over the trials when compared with controls. The control microinjected groups (saline, control peptide and misplaced pep-ephrinA4) were not different from each other (P>0.5). Cumulatively, these results show that microinjection of the ephrinA4 inhibitory pep-ephrinA4 peptide into LA impairs LTM.


EphrinA4 mimetic peptide targeted to EphA binding site impairs the formation of long-term fear memory in lateral amygdala.

Dines M, Lamprecht R - Transl Psychiatry (2014)

Inhibitory ephrinA4 mimetic peptide in the lateral amygdala (LA) impairs long-term fear memory (LTM) formation. (a) Pep-ephrinA4 (0.5 μl of 10 μg per μl; n=9), pep-control (0.5 μl of 10 μg per μl; n=5) or saline (n=7) were microinjected into rat LA 30 min before fear conditioning. Long-term memory was tested 24 h after training. Animals injected with pep-ephrinA4 were significantly impaired in fear memory (F(3)=6.428, P<0.003) when compared with pep-control (P<0.005), saline (P<0.02) or pep-ephrinA4 injected into areas surrounding the LA (P<0.03, n=11). The control microinjected groups (saline, control peptide and misplaced pep-ephrinA4) were not different from each other (P>0.5). (b) Cannula placements within the boundaries of lateral and basal amygdala (LBA) of pep-ephrinA4-, saline- and pep-control-microinjected rats. (c) Cannula placements of pep-ephrinA4 microinjected in areas near LA. CS, conditioned stimulus.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4203006&req=5

fig2: Inhibitory ephrinA4 mimetic peptide in the lateral amygdala (LA) impairs long-term fear memory (LTM) formation. (a) Pep-ephrinA4 (0.5 μl of 10 μg per μl; n=9), pep-control (0.5 μl of 10 μg per μl; n=5) or saline (n=7) were microinjected into rat LA 30 min before fear conditioning. Long-term memory was tested 24 h after training. Animals injected with pep-ephrinA4 were significantly impaired in fear memory (F(3)=6.428, P<0.003) when compared with pep-control (P<0.005), saline (P<0.02) or pep-ephrinA4 injected into areas surrounding the LA (P<0.03, n=11). The control microinjected groups (saline, control peptide and misplaced pep-ephrinA4) were not different from each other (P>0.5). (b) Cannula placements within the boundaries of lateral and basal amygdala (LBA) of pep-ephrinA4-, saline- and pep-control-microinjected rats. (c) Cannula placements of pep-ephrinA4 microinjected in areas near LA. CS, conditioned stimulus.
Mentions: We hypothesize that ephrinA4 interaction with EphA is essential for fear conditioning memory formation in LA and that microinjection of the inhibitory pep-ephrinA4 peptide into this brain area will interfere with the process of creating long-term fear memory. To test this hypothesis we compared the effects of the pep-ephrinA4 to that of the pep-control, that do not interact with EphA, on long-term fear memory formation in LA. We microinjected the pep-ephrinA4, pep-control or saline into the LA 30 min before fear conditioning. Rats with cannula tips at or within the boundaries of lateral and basal amygdala (LBA) were included in the data analysis (Figure 2). Long-term conditioned fear memory was assessed by measuring freezing responses elicited by the CS without the unconditioned stimulus 24 h after conditioning. Figure 2a shows that rats microinjected with pep-ephrinA4 froze significantly less (F(3)=6.428, P<0.003) than animals injected with saline (P<0.02), control peptide (P<0.005) or animals injected with pep-ephrinA4 in areas adjacent to the LA (P<0.03), showing that pep-ephrinA4-treated animals are impaired in long-term fear memory. The group × tone trial interaction did not differ significantly (F(8.481)=1.487, P>0.17), indicating that pep-ephrinA4 did not alter the rate of fear reduction over the trials when compared with controls. The control microinjected groups (saline, control peptide and misplaced pep-ephrinA4) were not different from each other (P>0.5). Cumulatively, these results show that microinjection of the ephrinA4 inhibitory pep-ephrinA4 peptide into LA impairs LTM.

Bottom Line: Acute systemic administration of pep-ephrinA4 1 h after training also impaired long-term fear conditioning memory formation.These results demonstrate that ephrinA4 binding sites in LA are essential for long-term fear memory formation.Moreover, our research shows that ephrinA4 binding sites may serve as a target for pharmacological treatment of fear and anxiety disorders.

View Article: PubMed Central - PubMed

Affiliation: Sagol Department of Neurobiology, University of Haifa, Haifa, Israel.

ABSTRACT
Fear conditioning leads to long-term fear memory formation and is a model for studying fear-related psychopathologies conditions such as phobias and posttraumatic stress disorder. Long-term fear memory formation is believed to involve alterations of synaptic efficacy mediated by changes in synaptic transmission and morphology in lateral amygdala (LA). EphrinA4 and its cognate Eph receptors are intimately involved in regulating neuronal morphogenesis, synaptic transmission and plasticity. To assess possible roles of ephrinA4 in fear memory formation we designed and used a specific inhibitory ephrinA4 mimetic peptide (pep-ephrinA4) targeted to EphA binding site. We show that this peptide, composed of the ephrinA4 binding domain, interacts with EphA4 and inhibits ephrinA4-induced phosphorylation of EphA4. Microinjection of the pep-ephrinA4 into rat LA 30 min before training impaired long- but not short-term fear conditioning memory. Microinjection of a control peptide derived from a nonbinding E helix site of ephrinA4, that does not interact with EphA, had no effect on fear memory formation. Microinjection of pep-ephrinA4 into areas adjacent to the amygdala had no effect on fear memory. Acute systemic administration of pep-ephrinA4 1 h after training also impaired long-term fear conditioning memory formation. These results demonstrate that ephrinA4 binding sites in LA are essential for long-term fear memory formation. Moreover, our research shows that ephrinA4 binding sites may serve as a target for pharmacological treatment of fear and anxiety disorders.

Show MeSH
Related in: MedlinePlus