Elsevier

Biological Psychiatry

Volume 80, Issue 10, 15 November 2016, Pages 796-806
Biological Psychiatry

Archival Report
G Protein-Gated K+ Channel Ablation in Forebrain Pyramidal Neurons Selectively Impairs Fear Learning

https://doi.org/10.1016/j.biopsych.2015.10.004Get rights and content

Abstract

Background

Cognitive dysfunction occurs in many debilitating conditions including Alzheimer’s disease, Down syndrome, schizophrenia, and mood disorders. The dorsal hippocampus is a critical locus of cognitive processes linked to spatial and contextual learning. G protein-gated inwardly rectifying potassium ion (GIRK/Kir3) channels, which mediate the postsynaptic inhibitory effect of many neurotransmitters, have been implicated in hippocampal-dependent cognition. Available evidence, however, derives primarily from constitutive gain-of-function models that lack cellular specificity.

Methods

We used constitutive and neuron-specific gene ablation models targeting an integral subunit of neuronal GIRK channels (GIRK2) to probe the impact of GIRK channels on associative learning and memory.

Results

Constitutive Girk2–/– mice exhibited a striking deficit in hippocampal-dependent (contextual) and hippocampal-independent (cue) fear conditioning. Mice lacking GIRK2 in gamma-aminobutyric acid neurons (GAD-Cre:Girk2flox/flox mice) exhibited a clear deficit in GIRK-dependent signaling in dorsal hippocampal gamma-aminobutyric acid neurons but no evident behavioral phenotype. Mice lacking GIRK2 in forebrain pyramidal neurons (CaMKII-Cre(+):Girk2flox/flox mice) exhibited diminished GIRK-dependent signaling in dorsal, but not ventral, hippocampal pyramidal neurons. CaMKII-Cre(+):Girk2flox/flox mice also displayed a selective impairment in contextual fear conditioning, as both cue fear and spatial learning were intact in these mice. Finally, loss of GIRK2 in forebrain pyramidal neurons correlated with enhanced long-term depression and blunted depotentiation of long-term potentiation at the Schaffer collateral/cornu ammonis 1 synapse in the dorsal hippocampus.

Conclusions

Our data suggest that GIRK channels in dorsal hippocampal pyramidal neurons are necessary for normal learning involving aversive stimuli and support the contention that dysregulation of GIRK-dependent signaling may underlie cognitive dysfunction in some disorders.

Section snippets

Animals

All animal experimentation was approved by the Institutional Animal Care and Use Committee at the University of Minnesota. Constitutive Girk2–/– and Girk2flox/flox mice were generated as described (38, 39). Girk2flox/flox mice were bred with B6.Cg-Tg(Camk2a-cre)T29-1Stl/J (calcium/calmodulin-dependent protein kinase II [CaMKII]-Cre) and B6N.Cg-Gad2tm2(cre)Zjh/J (glutamic acid decarboxylase [GAD]-Cre) (The Jackson Laboratory, Bar Harbor, Maine) to generate CaMKII-Cre:Girk2flox/flox and GAD-Cre:

Delay Fear Conditioning in Constitutive Girk2–/– Mice

We began by testing constitutive Girk2–/– mice in a delay fear conditioning paradigm that permits evaluation of both dorsal hippocampal-dependent (context) and independent (cue) associative learning and memory (6, 45, 46). Freezing triggered by the second and third conditioning tones was significantly reduced in Girk2–/– mice relative to wild-type control mice (Figure 1A), as was total freezing measured during conditioning (Figure 1B). On memory test day (24 hours later), Girk2–/– mice

Discussion

Mouse models exhibiting enhanced GIRK-dependent signaling show altered learning and memory (19, 32, 33, 34). Neither the behavioral impact of GIRK channel ablation nor the cell-specific contribution of GIRK channels to hippocampal-dependent cognition, however, has been examined. Here, we evaluated the impact of cell-specific ablation of GIRK channels on associative learning using a recently developed conditional Girk2 knockout mouse. We found that the loss of GIRK channels in forebrain

Acknowledgments and Disclosures

This work was supported by National Institutes of Health Grant Nos. MH106190 and DA007234 (NCV), DA007234 (ANZ), DA007097 (LLK), NS062158 (SM and MAB), DA036596 and DA026405 (KAM), and DA034696 and MH061933 (KW).

We thank Matt Novitch for assistance with the mouse behavioral testing and Jennifer Kutzke and Alex Shnaydruk for exceptional care of the mouse colony.

The authors report no biomedical financial interests or potential conflicts of interest.

References (82)

  • J Lazary et al.

    Epistatic interaction of CREB1 and KCNJ6 on rumination and negative emotionality

    Eur Neuropsychopharmacol

    (2011)
  • G Yao et al.

    Deletion of chromosome 21 disturbs human brain morphogenesis

    Genet Med

    (2006)
  • A Valetto et al.

    Molecular cytogenetic characterization of an interstitial deletion of chromosome 21 (21q22.13q22.3) in a patient with dysmorphic features, intellectual disability and severe generalized epilepsy

    Eur J Med Genet

    (2012)
  • NP Cramer et al.

    GABAB-GIRK2- mediated signaling in Down syndrome

    Adv Pharmacol

    (2010)
  • RJ Siarey et al.

    Abnormal synaptic plasticity in the Ts1Cje segmental trisomy 16 mouse model of Down syndrome

    Neuropharmacology

    (2005)
  • M Hearing et al.

    Repeated cocaine weakens GABA(B)-GIRK signaling in layer 5/6 pyramidal neurons in the prelimbic cortex

    Neuron

    (2013)
  • E Marron Fernandez de Velasco et al.

    Sex differences in GABABR-GIRK signaling in layer 5/6 pyramidal neurons of the mouse prelimbic cortex

    Neuropharmacology

    (2015)
  • YA Blednov et al.

    GIRK2 deficient mice. Evidence for hyperactivity and reduced anxiety

    Physiol Behav

    (2001)
  • H Taniguchi et al.

    A resource of Cre driver lines for genetic targeting of GABAergic neurons in cerebral cortex

    Neuron

    (2011)
  • SJ Coultrap et al.

    CaMKII regulation in information processing and storage

    Trends Neurosci

    (2012)
  • KE Horn et al.

    DCC expression by neurons regulates synaptic plasticity in the adult brain

    Cell Rep

    (2013)
  • JK Belanoff et al.

    Corticosteroids and cognition

    J Psychiatr Res

    (2001)
  • AV Beylin et al.

    Glucocorticoids are necessary for enhancing the acquisition of associative memories after acute stressful experience

    Horm Behav

    (2003)
  • A Kashefi et al.

    Effects of corticosterone on contextual fear consolidation in intact and ovariectomized female rats

    Neurobiol Learn Mem

    (2014)
  • G MacKenzie et al.

    Chronic stress shifts the GABA reversal potential in the hippocampus and increases seizure susceptibility

    Epilepsy Res

    (2015)
  • S Roychowdhury et al.

    5-HT1A and 5-HT4 receptor colocalization on hippocampal pyramidal cells

    Neuropharmacology

    (1994)
  • HR Snyder

    Major depressive disorder is associated with broad impairments on neuropsychological measures of executive function: A meta-analysis and review

    Psychol Bull

    (2013)
  • N Malakooti et al.

    Role of metal ions in the cognitive decline of Down syndrome

    Front Aging Neurosci

    (2014)
  • KP Giese et al.

    Autophosphorylation at Thr286 of the alpha calcium-calmodulin kinase II in LTP and learning

    Science

    (1998)
  • K Nakazawa et al.

    Requirement for hippocampal CA3 NMDA receptors in associative memory recall

    Science

    (2002)
  • A Ren et al.

    Regulation of hippocampus-dependent memory by the zinc finger protein Zbtb20 in mature CA1 neurons

    J Physiol

    (2012)
  • JR Whitlock et al.

    Learning induces long-term potentiation in the hippocampus

    Science

    (2006)
  • MP Arolfo et al.

    Baclofen infused in rat hippocampal formation impairs spatial learning

    Hippocampus

    (1998)
  • MR Zarrindast et al.

    Effects of intrahippocampal injection of GABAergic drugs on memory retention of passive avoidance learning in rats

    J Psychopharmacol

    (2002)
  • O Stiedl et al.

    Involvement of the 5-HT1A receptors in classical fear conditioning in C57BL/6J mice

    J Neurosci

    (2000)
  • LH Jacobson et al.

    GABA(B(1)) receptor isoforms differentially mediate the acquisition and extinction of aversive taste memories

    J Neurosci

    (2006)
  • AM Kleschevnikov et al.

    Deficits in cognition and synaptic plasticity in a mouse model of Down syndrome ameliorated by GABAB receptor antagonists

    J Neurosci

    (2012)
  • C Luscher et al.

    Emerging roles for G protein-gated inwardly rectifying potassium (GIRK) channels in health and disease

    Nat Rev Neurosci

    (2010)
  • C Karschin et al.

    IRK(1-3) and GIRK(1-4) inwardly rectifying K+ channel mRNAs are differentially expressed in the adult rat brain

    J Neurosci

    (1996)
  • L Koyrakh et al.

    Molecular and cellular diversity of neuronal G-protein-gated potassium channels

    J Neurosci

    (2005)
  • K Yamada et al.

    Genome-wide association study of schizophrenia in Japanese population

    PLoS One

    (2011)
  • Cited by (25)

    • Infralimbic cortex pyramidal neuron GIRK signaling contributes to regulation of cognitive flexibility but not affect-related behavior in male mice

      2021, Physiology and Behavior
      Citation Excerpt :

      Together, these data establish that loss of GIRK1 is sufficient to increase ILC pyramidal neuron excitation and firing and dynamically impact other intrinsic properties not previously observed with GIRK1 knockout in PrLC pyramidal neurons [6]. Motivation for reward, learning and memory, and affective behaviors is impacted by alterations in GIRK signaling [6, 60, 80, 90, 104, 105]. Our recent work highlights a role for PrLC GIRK signaling in these behaviors, however contributions of ILC GIRK channels remains unexplored.

    • Therapeutic potential of targeting G protein-gated inwardly rectifying potassium (GIRK) channels in the central nervous system

      2021, Pharmacology and Therapeutics
      Citation Excerpt :

      Similarly, LTP of GirK currents has been also described (Huang et al., 2005) and recently proposed as a mechanism involved in the extinction of excitatory potentiation to basal amplitude levels (Sánchez-Rodríguez et al., 2019). Together, these results show the importance of an optimal range of GirK signaling for normal hippocampus-dependent cognition (Sánchez-Rodríguez et al., 2020; Victoria et al., 2016). A wide variety of neurotransmitters and neuromodulators can induce the activation of GirK channels (Fig. 3), including γ-aminobutyric acid (GABA), serotonin, adenosine, dopamine, opioids and somatostatin (Glaaser & Slesinger, 2015).

    • Activation of V<inf>1a</inf> vasopressin receptors excite subicular pyramidal neurons by activating TRPV1 and depressing GIRK channels

      2021, Neuropharmacology
      Citation Excerpt :

      For example, activation of V1a receptors exerts anxiogenic effects (Bielsky et al., 2004, 2005; Egashira et al., 2007; Landgraf et al., 1995; Simon et al., 2008), although the underlying cellular and molecular mechanisms have not been determined. Because TRPV1 channels (Ho et al., 2012; Marsch et al., 2007), GIRK channels (Pravetoni and Wickman, 2008; Victoria et al., 2016; Wydeven et al., 2014), PLCβ (McOmish et al., 2008; Xiao et al., 2012) and PKC (Bowers et al., 2000; Lesscher et al., 2008; Liu et al., 2014) are involved in the modulation of anxiety, our results may provide an ionic and signaling mechanisms to explain the anxiogenic effects of AVP. Furthermore, activation of V1a receptors facilitates learning and memory (Bielsky et al., 2005; Nephew and Bridges, 2008) and both TRPV1 (Bannazadeh et al., 2017; Bashiri et al., 2018; Edwards, 2014; Genro et al., 2012) and GIRK channels (Mayfield et al., 2015) are involved in cognitive functions.

    • Suppression of inhibitory G protein signaling in forebrain pyramidal neurons triggers plasticity of glutamatergic neurotransmission in the nucleus accumbens core

      2017, Neuropharmacology
      Citation Excerpt :

      Resting membrane potentials were also depolarized in neurons from Cre(+) subjects from both CaMKIICre:Girk1fl/fl (−61.9 ± 0.8 vs. −64.3 ± 0.4 mV; t16 = 2.5, P < 0.05) and CaMKIICre:Girk2fl/fl (−64.9 ± 1.3 vs. −70.3 ± 0.6 mV; t19.2 = 3.8, P < 0.01) mouse lines. Consistent with the reported pattern of Cre-dependent recombination in CaMKIICre(+) mice, we also observed reduced baclofen-induced currents in pyramidal neurons of the basolateral amygdala from CaMKIICre(+):Girk1fl/fl mice (Fig. S2), and in CA1 pyramidal neurons of the dorsal hippocampus from CaMKIICre(+):Girk2fl/fl mice (Victoria et al., 2016). Thus, CaMKIICre(+):Girk1fl/fl and CaMKIICre(+):Girk2fl/fl mice exhibit a loss of GIRK-dependent signaling in multiple forebrain pyramidal neuron populations.

    View all citing articles on Scopus
    View full text