autoradiography-as-simple-powerful-method-for-visualization

Autoradiography as a Simple and Powerful Method for Visualization and Characterization of Pharmacological Targets

In vitro autoradiography aims to visualize the anatomical distribution of a protein of interest in tissue from experimental animals as well as humans. The ...

University of Copenhagen

The numerous γ-aminobutyric acid type A receptor (GABAAR) subtypes are differentially expressed and mediate distinct functions at neuronal level. In this study we have investigated GABAAR-mediated modulation of the spontaneous activity patterns of primary neuronal networks from murine frontal cortex by characterizing the effects induced by a wide selection of pharmacological tools at a plethora of activity parameters in microelectrode array (MEA) recordings. The basic characteristics of the primary cortical neurons used in the recordings were studied in some detail, and the expression levels of various GABAAR subunits were investigated by western blotting and RT-qPCR. In the MEA recordings, the pan-GABAAR agonist muscimol and the GABABR agonist baclofen were observed to mediate phenotypically distinct changes in cortical network activity. Selective augmentation of αβγ GABAAR signaling by diazepam and of δ-containing GABAAR (δ-GABAAR) signaling by DS1 produced pronounced changes in the majority of the activity parameters, both drugs mediating similar patterns of activity changes as muscimol. The apparent importance of δ-GABAAR signaling for network activity was largely corroborated by the effects induced by the functionally selective δ-GABAAR agonists THIP and Thio-THIP, whereas the δ-GABAAR selective potentiator DS2 only mediated modest effects on network activity, even when co-applied with low THIP concentrations. Interestingly, diazepam exhibited dramatically right-shifted concentration-response relationships at many of the activity parameters when co-applied with a trace concentration of DS1 compared to when applied alone. In contrast, the potencies and efficacies displayed by DS1 at the networks were not substantially altered by the concomitant presence of diazepam. In conclusion, the holistic nature of the information extractable from the MEA recordings offers interesting insights into the contributions of various GABAAR subtypes/subgroups to cortical network activity and the putative functional interplay between these receptors in these neurons.

Functional characterization of GABAA receptor-mediated modulation of cortical neuron network activity in microelectrode array recordings.

Serotonin receptors and glutamate signaling have been implicated in the pathophysiology and treatment of compulsive spectrum disorders. Schedule-Induced Polydipsia (SIP), characterized by excessive drinking under intermittent food reinforcement schedules, is a valid model for studying the compulsive phenotype in rats. We explored the expression, function, and neurochemistry of 5-HT receptors in the frontal cortex (FC) of rats with individual differences to compulsivity. Rats were selected for high (HD) versus low (LD) drinking on SIP. First, we measured 5-HT, 5-HT, and mGlu receptors and serotonin transporter binding in different brain regions. Second, we assessed the effect of microinfusion into the medial prefrontal cortex (mPFC) of the 5-HT receptor agonist DOI, the mGlu agonist LY379268, and the combination of DOI with the 5-HT receptor antagonist M100907 and the 5-HT receptor antagonist SB242084. Finally, we measured the serotonin and glutamate efflux in mPFC in basal condition and after DOI local application. The compulsive HD rats showed a specific reduction of 5-HT receptor binding in FC compared to LD rats. The highest dose of DOI reduced compulsive drinking in HD rats on SIP, whereas LY379268 did not induce any significant effect. The 5-HT receptor antagonist M100907 reversed the DOI induced reduction on compulsive drinking in HD rats while blocking the 5-HT receptor did not affect SIP. Compulsive HD rats showed increased serotonin and decreased glutamate efflux in basal conditions that were modified by the DOI application. These findings indicate that reduced 5-HT receptor binding and glutamate neurochemical mechanisms may underlie compulsive behavior vulnerability.

Reduced cortical serotonin 5-HT receptor binding and glutamate activity in high compulsive drinker rats.

γ-aminobutyric acid (GABA) mediates its physiological effects through the GABA and GABA receptors. In this study the putative expression of GABAR and GABAR subunits in human myometrium tissue was investigated.

Article	Year
Functional characterization of GABAA receptor-mediated modulation of cortical neuron network activity in microelectrode array recordings. PloS one\| PubMed ID: 29028808	2017
Reduced cortical serotonin 5-HT receptor binding and glutamate activity in high compulsive drinker rats. Neuropharmacology\| PubMed ID: 30201211	2018
Profiling of GABA and GABA receptor expression in the myometrium of the human uterus. Life sciences\| PubMed ID: 30343129	2018

Anders Bue Klein

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