scholarly journals Mu-Opioids Suppress GABAergic Synaptic Transmission onto Orbitofrontal Cortex Pyramidal Neurons with Subregional Selectivity

2020 ◽  
Vol 40 (31) ◽  
pp. 5894-5907
Author(s):  
Benjamin K. Lau ◽  
Brittany P. Ambrose ◽  
Catherine S. Thomas ◽  
Min Qiao ◽  
Stephanie L. Borgland
Keyword(s):  
Synaptic Transmission ◽  
Orbitofrontal Cortex ◽  
Pyramidal Neurons ◽  
Mu Opioids ◽  
Gabaergic Synaptic Transmission

scholarly journals Mu-opioids suppress GABAergic synaptic transmission onto orbitofrontal cortex pyramidal neurons with subregional selectivity

2020 ◽  
Author(s):  
Benjamin K. Lau ◽  
Brittany P. Ambrose ◽  
Catherine S. Thomas ◽  
Min Qiao ◽  
Stephanie L. Borgland
Keyword(s):  
Synaptic Transmission ◽  
Opioid Receptor ◽  
Orbitofrontal Cortex ◽  
Pyramidal Neurons ◽  
Mu Opioid Receptor ◽  
Mu Opioid ◽  
Inhibitory Synaptic Transmission ◽  
Receptor Coupling ◽  
Mu Opioids ◽  
Gabaergic Synaptic Transmission

AbstractThe orbitofrontal cortex (OFC) plays a critical role in evaluating outcomes in a changing environment. Administering opioids to the OFC can alter the hedonic reaction to food rewards and increase their consumption in a subregion specific manner. However, it is unknown how mu-opioid signalling influences synaptic transmission in the OFC. Thus, we investigated the cellular actions of mu-opioids within distinct subregions of the OFC. Using in-vitro patch clamp electrophysiology in brain slices containing the OFC, we found that the mu-opioid agonist, DAMGO produced a concentration-dependant inhibition of GABAergic synaptic transmission onto medial OFC (mOFC), but not lateral OFC (lOFC) neurons. This effect was mediated by presynaptic mu-opioid receptor activation of local parvalbumin (PV+)-expressing interneurons. The DAMGO-induced suppression of inhibition was long-lasting and not reversed upon washout of DAMGO, or by application of the mu-opioid receptor antagonist, CTAP, suggesting an inhibitory long-term depression (iLTD) induced by an exogenous mu-opioid. We show that LTD at inhibitory synapses is dependent on downstream cAMP/PKA signaling, which differs between the mOFC and lOFC. Finally, we demonstrate that endogenous opioid release triggered via moderate physiological stimulation can induce LTD. Taken together, these results suggest that presynaptic mu-opioid stimulation of local PV+ interneurons induces a long-lasting suppression of GABAergic synaptic transmission, which depends on subregional differences in mu-opioid receptor coupling to the downstream cAMP/PKA intracellular cascade. These findings provide mechanistic insight into the opposing functional effects produced by mu-opioids within the OFC.Significance StatementConsidering that both the OFC and the opioid system regulate reward, motivation, and food intake; understanding the role of opioid signaling within the OFC is fundamental for a mechanistic understanding of the sequelae for several psychiatric disorders. This study makes several novel observations. First, mu-opioids induce a long-lasting suppression of inhibitory synaptic transmission onto OFC pyramidal neurons in a regionally selective manner. Secondly, mu-opioids recruit PV+ inputs to suppress inhibitory synaptic transmission in the mOFC. Thirdly, the regional selectivity of mu-opioid action of endogenous opioids is due to the efficacy of mu-opioid receptor coupling to the downstream cAMP/PKA intracellular cascades. These experiments are the first to reveal a cellular mechanism of opioid action within the OFC.

scholarly journals Dopamine D2 receptors modulate intrinsic properties and synaptic transmission of parvalbumin interneurons in the mouse primary motor cortex

2019 ◽  
Author(s):  
Jérémy Cousineau ◽  
Léa Lescouzères ◽  
Anne Taupignon ◽  
Lorena Delgado-Zabalza ◽  
Emmanuel Valjent ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Synaptic Transmission ◽  
Motor Skills ◽  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
D2 Receptors ◽  
Receptor Subtypes ◽  
Parvalbumin Interneurons ◽  
Layer V ◽  
Gabaergic Synaptic Transmission

AbstractDopamine (DA) plays a crucial role in the control of motor and higher cognitive functions such as learning, working memory and decision making. The primary motor cortex (M1), which is essential for motor control and the acquisition of motor skills, receives dopaminergic inputs in its superficial and deep layers from the midbrain. However, the precise action of DA and DA receptor subtypes on the cortical microcircuits of M1 remains poorly understood. The aim of this work was to investigate how DA, through the activation of D2 receptors (D2R), modulates the cellular and synaptic activity of M1 parvalbumin-expressing interneurons (PVINs) which are crucial to regulate the spike output of pyramidal neurons (PNs). By combining immunofluorescence, ex vivo electrophysiology, pharmacology and optogenetics approaches, we show that D2R activation increases neuronal excitability of PVINs and GABAergic synaptic transmission between PVINs and PNs in layer V of M1. Our data reveal a mechanism through which cortical DA modulates M1 microcircuitry and might participate in the acquisition of motor skills.Significance StatementPrimary motor cortex (M1), which is a region essential for motor control and the acquisition of motor skills, receives dopaminergic inputs from the midbrain. However, precise action of dopamine and its receptor subtypes on specific cell types in M1 remained poorly understood. Here, we demonstrate in M1 that dopamine D2 receptors (D2R) are present in parvalbumin interneurons (PVINs) and their activation increases the excitability of the PVINs, which are crucial to regulate the spike output of pyramidal neurons (PNs). Moreover the activation of the D2R facilitates the GABAergic synaptic transmission of those PVINs on layer V PNs. These results highlight how cortical dopamine modulates the functioning of M1 microcircuit which activity is disturbed in hypo- and hyperdopaminergic states.

scholarly journals Serotoninergic modulation of GABAergic synaptic transmission in developing rat CA3 pyramidal neurons

2007 ◽  
Vol 103 (6) ◽  
pp. 2342-2353 ◽  
Author(s):  
In-Sun Choi ◽  
Jin-Hwa Cho ◽  
Jung-Tak Kim ◽  
Eun-Joo Park ◽  
Maan-Gee Lee ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Pyramidal Neurons ◽  
Ca3 Pyramidal Neurons ◽  
Developing Rat ◽  
Gabaergic Synaptic Transmission

Possible role of mitochondria in posttetanic potentiation of GABAergic synaptic transmission in rat neocortical cell cultures

Synapse ◽  
2005 ◽  
Vol 58 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Maksim V. Storozhuk ◽  
Svetlana Y. Ivanova ◽  
Pavel M. Balaban ◽  
Platon G. Kostyuk
Keyword(s):  
Synaptic Transmission ◽  
Cell Cultures ◽  
Posttetanic Potentiation ◽  
Gabaergic Synaptic Transmission

Two Mechanisms That Raise Free Intracellular Calcium in Rat Hippocampal Neurons During Hypoosmotic and Low NaCl Treatment

2000 ◽  
Vol 83 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Aren J. Borgdorff ◽  
George G. Somjen ◽  
Wytse J. Wadman
Keyword(s):  
Synaptic Transmission ◽  
Intracellular Calcium ◽  
Hippocampal Neurons ◽  
Pyramidal Neurons ◽  
Hippocampal Slices ◽  
Cell Swelling ◽  
Tissue Slices ◽  
Extracellular Medium ◽  
Calcium Activity ◽  
Hippocampal Pyramidal Neurons

Previous studies have shown that exposing hippocampal slices to low osmolarity (πo) or to low extracellular NaCl concentration ([NaCl]o) enhances synaptic transmission and also causes interstitial calcium ([Ca2+]o) to decrease. Reduction of [Ca2+]o suggests cellular uptake and could explain the potentiation of synaptic transmission. We measured intracellular calcium activity ([Ca2+]i) using fluorescent indicator dyes. In CA1 hippocampal pyramidal neurons in tissue slices, lowering πo by ∼70 mOsm caused “resting” [Ca2+]i as well as synaptically or directly stimulated transient increases of calcium activity (Δ[Ca2+]i) to transiently decrease and then to increase. In dissociated cells, lowering πo by ∼70 mOsm caused [Ca2+]i to almost double on average from 83 to 155 nM. The increase of [Ca2+]i was not significantly correlated with hypotonic cell swelling. Isoosmotic (mannitol- or sucrose-substituted) lowering of [NaCl]o, which did not cause cell swelling, also raised [Ca2+]i. Substituting NaCl with choline-Cl or Na-methyl-sulfate did not affect [Ca2+]i. In neurons bathed in calcium-free medium, lowering πo caused a milder increase of [Ca2+]i, which was correlated with cell swelling, but in the absence of external Ca2+, isotonic lowering of [NaCl]o triggered only a brief, transient response. We conclude that decrease of extracellular ionic strength (i.e., in both low πo and low [NaCl]o) causes a net influx of Ca2+ from the extracellular medium whereas cell swelling, or the increase in membrane tension, is a signal for the release of Ca2+ from intracellular stores.

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