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The NO-cGMP-PKG signaling pathway coordinately regulates ERK and ERK-driven gene expression at pre- and postsynaptic sites following LTP-inducing stimulation of thalamo-amygdala synapses.

Ping J, Schafe GE - Neural Plast. (2011)

Bottom Line: Here, we show that LTP-inducing stimulation of thalamo-LA inputs regulates the activation of ERK and the expression of ERK-driven immediate early genes (IEGs) in both the LA and MGm/PIN.Further, we show that pharmacological blockade of NMDAR-driven synaptic plasticity, NOS activation, or PKG signaling in the LA significantly impairs high-frequency stimulation-(HFS-) induced ERK activation and IEG expression in both regions, while blockade of extracellular NO signaling in the LA impairs HFS-induced ERK activation and IEG expression exclusively in the MGm/PIN.These findings suggest that NMDAR-driven synaptic plasticity and NO-cGMP-PKG signaling within the LA coordinately regulate ERK-driven gene expression in both the LA and the MGm/PIN following LTP induction at thalamo-LA synapses, and that synaptic plasticity in the LA promotes ERK-driven transcription in MGm/PIN neurons via NO-driven "retrograde signaling".

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Yale University, New Haven, CT 06520, USA.

ABSTRACT
Long-term potentiation (LTP) at thalamic input synapses to the lateral nucleus of the amygdala (LA) has been proposed as a cellular mechanism of the formation of auditory fear memories. We have previously shown that signaling via ERK/MAPK in both the LA and the medial division of the medial geniculate nucleus/posterior intralaminar nucleus (MGm/PIN) is critical for LTP at thalamo-LA synapses. Here, we show that LTP-inducing stimulation of thalamo-LA inputs regulates the activation of ERK and the expression of ERK-driven immediate early genes (IEGs) in both the LA and MGm/PIN. Further, we show that pharmacological blockade of NMDAR-driven synaptic plasticity, NOS activation, or PKG signaling in the LA significantly impairs high-frequency stimulation-(HFS-) induced ERK activation and IEG expression in both regions, while blockade of extracellular NO signaling in the LA impairs HFS-induced ERK activation and IEG expression exclusively in the MGm/PIN. These findings suggest that NMDAR-driven synaptic plasticity and NO-cGMP-PKG signaling within the LA coordinately regulate ERK-driven gene expression in both the LA and the MGm/PIN following LTP induction at thalamo-LA synapses, and that synaptic plasticity in the LA promotes ERK-driven transcription in MGm/PIN neurons via NO-driven "retrograde signaling".

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High-frequency stimulation of the MGm/PIN promotes ERK phosphorylation in LA at 5 min and in the MGm/PIN at 30 min after stimulation. (a) Placement of stimulation electrode and schematic representation of the experimental protocol.  (b) Schematic representation of the HFS and LFS stimulation protocols. Anesthetized rats were given HFS or LFS and sacrificed at 5 min, 30 min or 60 min after stimulation. (c) Images of Western blots for phospho-ERK1/2 and associated GAPDH loading controls from LA (upper) and MGm/PIN (lower) samples after HFS or LFS. (d-e) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from LA punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 6; LFS: n = 8), or 60 min (n = 6). (f-g) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from MGm/PIN punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 5; LFS: n = 5), or 60 min (n = 6). For each figure, phospho-ERK1/2 levels have been normalized to total-ERK1/2 levels for each sample and counts on the ipsilateral (stimulated) side have been expressed as a percentage of those on the contralateral (nonstimulated) side. *P < .05 relative to the ipsilateral side N.S. = not significant.
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fig1: High-frequency stimulation of the MGm/PIN promotes ERK phosphorylation in LA at 5 min and in the MGm/PIN at 30 min after stimulation. (a) Placement of stimulation electrode and schematic representation of the experimental protocol. (b) Schematic representation of the HFS and LFS stimulation protocols. Anesthetized rats were given HFS or LFS and sacrificed at 5 min, 30 min or 60 min after stimulation. (c) Images of Western blots for phospho-ERK1/2 and associated GAPDH loading controls from LA (upper) and MGm/PIN (lower) samples after HFS or LFS. (d-e) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from LA punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 6; LFS: n = 8), or 60 min (n = 6). (f-g) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from MGm/PIN punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 5; LFS: n = 5), or 60 min (n = 6). For each figure, phospho-ERK1/2 levels have been normalized to total-ERK1/2 levels for each sample and counts on the ipsilateral (stimulated) side have been expressed as a percentage of those on the contralateral (nonstimulated) side. *P < .05 relative to the ipsilateral side N.S. = not significant.

Mentions: Our lab has recently shown that HFS of the thalamo-LA pathway regulates ERK phosphorylation in the LA and that pharmacological blockade of ERK activation in the LA impairs LTP at thalamo-LA synapses, in vivo [22]. Interestingly, ERK activation at the level of the MGm/PIN also appears to be critical for LTP at thalamo-LA synapses; intra-MGm/PIN infusion of a MEK inhibitor also impairs LTP in the thalamo-LA pathway [23]. This pattern of findings collectively suggests that LTP at thalamo-LA synapses regulates ERK activation in both the LA and the MGm/PIN. In the present experiment, we tested this hypothesis by examining phospho-ERK in both LA and MGm/PIN in anesthetized rats after LTP-inducing stimulation of the thalamo-LA pathway, in vivo (Figure 1(a)). Rats were given 100 Hz HFS of the MGm/PIN (Figure 1(b)), a protocol that induces a reliable LTP at thalamo-LA synapses [22, 25, 26]. Control rats received 2.5 Hz LFS (Figure 1(b)), a protocol that does not induce LTP [22]. Rats were then sacrificed at different time points after stimulation (5 min, 30 min, or 60 min).


The NO-cGMP-PKG signaling pathway coordinately regulates ERK and ERK-driven gene expression at pre- and postsynaptic sites following LTP-inducing stimulation of thalamo-amygdala synapses.

Ping J, Schafe GE - Neural Plast. (2011)

High-frequency stimulation of the MGm/PIN promotes ERK phosphorylation in LA at 5 min and in the MGm/PIN at 30 min after stimulation. (a) Placement of stimulation electrode and schematic representation of the experimental protocol.  (b) Schematic representation of the HFS and LFS stimulation protocols. Anesthetized rats were given HFS or LFS and sacrificed at 5 min, 30 min or 60 min after stimulation. (c) Images of Western blots for phospho-ERK1/2 and associated GAPDH loading controls from LA (upper) and MGm/PIN (lower) samples after HFS or LFS. (d-e) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from LA punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 6; LFS: n = 8), or 60 min (n = 6). (f-g) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from MGm/PIN punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 5; LFS: n = 5), or 60 min (n = 6). For each figure, phospho-ERK1/2 levels have been normalized to total-ERK1/2 levels for each sample and counts on the ipsilateral (stimulated) side have been expressed as a percentage of those on the contralateral (nonstimulated) side. *P < .05 relative to the ipsilateral side N.S. = not significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3065048&req=5

fig1: High-frequency stimulation of the MGm/PIN promotes ERK phosphorylation in LA at 5 min and in the MGm/PIN at 30 min after stimulation. (a) Placement of stimulation electrode and schematic representation of the experimental protocol. (b) Schematic representation of the HFS and LFS stimulation protocols. Anesthetized rats were given HFS or LFS and sacrificed at 5 min, 30 min or 60 min after stimulation. (c) Images of Western blots for phospho-ERK1/2 and associated GAPDH loading controls from LA (upper) and MGm/PIN (lower) samples after HFS or LFS. (d-e) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from LA punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 6; LFS: n = 8), or 60 min (n = 6). (f-g) Mean (±SEM) percent phospho-ERK1/2 immunoreactivity from MGm/PIN punches taken from rats receiving HFS (left) or LFS (right) and sacrificed at 5 min (HFS: n = 6; LFS: n = 6), 30 min (HFS: n = 5; LFS: n = 5), or 60 min (n = 6). For each figure, phospho-ERK1/2 levels have been normalized to total-ERK1/2 levels for each sample and counts on the ipsilateral (stimulated) side have been expressed as a percentage of those on the contralateral (nonstimulated) side. *P < .05 relative to the ipsilateral side N.S. = not significant.
Mentions: Our lab has recently shown that HFS of the thalamo-LA pathway regulates ERK phosphorylation in the LA and that pharmacological blockade of ERK activation in the LA impairs LTP at thalamo-LA synapses, in vivo [22]. Interestingly, ERK activation at the level of the MGm/PIN also appears to be critical for LTP at thalamo-LA synapses; intra-MGm/PIN infusion of a MEK inhibitor also impairs LTP in the thalamo-LA pathway [23]. This pattern of findings collectively suggests that LTP at thalamo-LA synapses regulates ERK activation in both the LA and the MGm/PIN. In the present experiment, we tested this hypothesis by examining phospho-ERK in both LA and MGm/PIN in anesthetized rats after LTP-inducing stimulation of the thalamo-LA pathway, in vivo (Figure 1(a)). Rats were given 100 Hz HFS of the MGm/PIN (Figure 1(b)), a protocol that induces a reliable LTP at thalamo-LA synapses [22, 25, 26]. Control rats received 2.5 Hz LFS (Figure 1(b)), a protocol that does not induce LTP [22]. Rats were then sacrificed at different time points after stimulation (5 min, 30 min, or 60 min).

Bottom Line: Here, we show that LTP-inducing stimulation of thalamo-LA inputs regulates the activation of ERK and the expression of ERK-driven immediate early genes (IEGs) in both the LA and MGm/PIN.Further, we show that pharmacological blockade of NMDAR-driven synaptic plasticity, NOS activation, or PKG signaling in the LA significantly impairs high-frequency stimulation-(HFS-) induced ERK activation and IEG expression in both regions, while blockade of extracellular NO signaling in the LA impairs HFS-induced ERK activation and IEG expression exclusively in the MGm/PIN.These findings suggest that NMDAR-driven synaptic plasticity and NO-cGMP-PKG signaling within the LA coordinately regulate ERK-driven gene expression in both the LA and the MGm/PIN following LTP induction at thalamo-LA synapses, and that synaptic plasticity in the LA promotes ERK-driven transcription in MGm/PIN neurons via NO-driven "retrograde signaling".

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Yale University, New Haven, CT 06520, USA.

ABSTRACT
Long-term potentiation (LTP) at thalamic input synapses to the lateral nucleus of the amygdala (LA) has been proposed as a cellular mechanism of the formation of auditory fear memories. We have previously shown that signaling via ERK/MAPK in both the LA and the medial division of the medial geniculate nucleus/posterior intralaminar nucleus (MGm/PIN) is critical for LTP at thalamo-LA synapses. Here, we show that LTP-inducing stimulation of thalamo-LA inputs regulates the activation of ERK and the expression of ERK-driven immediate early genes (IEGs) in both the LA and MGm/PIN. Further, we show that pharmacological blockade of NMDAR-driven synaptic plasticity, NOS activation, or PKG signaling in the LA significantly impairs high-frequency stimulation-(HFS-) induced ERK activation and IEG expression in both regions, while blockade of extracellular NO signaling in the LA impairs HFS-induced ERK activation and IEG expression exclusively in the MGm/PIN. These findings suggest that NMDAR-driven synaptic plasticity and NO-cGMP-PKG signaling within the LA coordinately regulate ERK-driven gene expression in both the LA and the MGm/PIN following LTP induction at thalamo-LA synapses, and that synaptic plasticity in the LA promotes ERK-driven transcription in MGm/PIN neurons via NO-driven "retrograde signaling".

Show MeSH
Related in: MedlinePlus