Zhi-Peng Liu1, Qing-Hai He2, Han-Qing Pan1, Xiao-Bin Xu1, Wen-Bing Chen1, Ye He3, Jin Zhou1, Wen-Hua Zhang1, Jun-Yu Zhang4, Xiao-Ping Ying5, Ren-Wen Han6, Bao-Ming Li1, Tian-Ming Gao2, Bing-Xing Pan7. 1. Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang. 2. State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province; Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou. 3. Medical Experiment Center, Nanchang University, Nanchang. 4. Department of Biotechnology, School of Life Sciences, Nanchang University, Nanchang. 5. Department of Neurology, the 2nd Affiliated Hospital, , Nanchang University, Nanchang. 6. Institute of Translational Medicine, Nanchang University, Nanchang. 7. Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang; Department of Neurology, the 2nd Affiliated Hospital, , Nanchang University, Nanchang; Jiangxi Provincial Collaborative Innovation Center for Cardiovascular, Digestive and Neuropsychiatric Diseases, Jiangxi, China. Electronic address: panbingxing@ncu.edu.cn.
Abstract
BACKGROUND: Maintaining gamma-aminobutyric acidergic (GABAergic) inhibition in the amygdala within a physiological range is critical for the appropriate expression of emotions such as fear and anxiety. The synaptic GABA type A receptor (GABAAR) is generally known to mediate the primary component of amygdala inhibition and prevent inappropriate expression of fear. However, little is known about the contribution of the extrasynaptic GABAAR to amygdala inhibition and fear. METHODS: By using mice expressing green fluorescent protein in interneurons (INs) and lacking the δ subunit-containing GABAAR (GABAA(δ)R), which is exclusively situated in the extrasynaptic membrane, we systematically investigated the role of GABAA(δ)R in regulating inhibition in the lateral amygdala (LA) and fear learning using the combined approaches of immunohistochemistry, electrophysiology, and behavior. RESULTS: In sharp contrast to the established role of synaptic GABAAR in mediating LA inhibition, we found that either pharmacological or physiological recruitment of GABAA(δ)R resulted in the weakening of GABAergic transmission onto projection neurons in LA while leaving the glutamatergic transmission unaltered, suggesting disinhibition by GABAA(δ)R. The disinhibition arose from IN-specific expression of GABAA(δ)R with its activation decreasing the input resistance of local INs and suppressing their activation. Genetic deletion of GABAA(δ)R attenuated its role in suppressing LA INs and disinhibiting LA. Importantly, the GABAA(δ)R facilitated long-term potentiation in sensory afferents to LA and permitted the expression of learned fear. CONCLUSIONS: Our findings suggest that GABAA(δ)R serves as a brake rather than a mediator of GABAergic inhibition in LA. The disinhibition by GABAA(δ)R may help to prevent excessive suppression of amygdala activity and thus ensure the expression of emotion.
BACKGROUND: Maintaining gamma-aminobutyric acidergic (GABAergic) inhibition in the amygdala within a physiological range is critical for the appropriate expression of emotions such as fear and anxiety. The synaptic GABA type A receptor (GABAAR) is generally known to mediate the primary component of amygdala inhibition and prevent inappropriate expression of fear. However, little is known about the contribution of the extrasynaptic GABAAR to amygdala inhibition and fear. METHODS: By using mice expressing green fluorescent protein in interneurons (INs) and lacking the δ subunit-containing GABAAR (GABAA(δ)R), which is exclusively situated in the extrasynaptic membrane, we systematically investigated the role of GABAA(δ)R in regulating inhibition in the lateral amygdala (LA) and fear learning using the combined approaches of immunohistochemistry, electrophysiology, and behavior. RESULTS: In sharp contrast to the established role of synaptic GABAAR in mediating LA inhibition, we found that either pharmacological or physiological recruitment of GABAA(δ)R resulted in the weakening of GABAergic transmission onto projection neurons in LA while leaving the glutamatergic transmission unaltered, suggesting disinhibition by GABAA(δ)R. The disinhibition arose from IN-specific expression of GABAA(δ)R with its activation decreasing the input resistance of local INs and suppressing their activation. Genetic deletion of GABAA(δ)R attenuated its role in suppressing LA INs and disinhibiting LA. Importantly, the GABAA(δ)R facilitated long-term potentiation in sensory afferents to LA and permitted the expression of learned fear. CONCLUSIONS: Our findings suggest that GABAA(δ)R serves as a brake rather than a mediator of GABAergic inhibition in LA. The disinhibition by GABAA(δ)R may help to prevent excessive suppression of amygdala activity and thus ensure the expression of emotion.
Authors: Justine D Landin; Magdalena Palac; Jenna M Carter; Yvette Dzumaga; Jessica L Santerre-Anderson; Gina M Fernandez; Lisa M Savage; Elena I Varlinskaya; Linda P Spear; Scott D Moore; H Scott Swartzwelder; Rebekah L Fleming; David F Werner Journal: Neuropharmacology Date: 2019-03-26 Impact factor: 5.250
Authors: Navatha Alugubelly; Afzaal N Mohammad; Mariola J Edelmann; Bindu Nanduri; Mohammed Sayed; Juw Won Park; Russell L Carr Journal: Behav Brain Res Date: 2019-09-04 Impact factor: 3.332