Pharmacological characterisation of murine α4β1δ GABAA receptors expressed in Xenopus oocytes

TY - JOUR

T1 - Pharmacological characterisation of murine α4β1δ GABAA receptors expressed in Xenopus oocytes

AU - Villumsen, Inge S

AU - Wellendorph, Petrine

AU - Smart, Trevor G

PY - 2015/3/5

Y1 - 2015/3/5

N2 - Background: AA receptor subunit composition has a profound effect on the receptor's physiological and pharmacological properties. The receptor β subunit is widely recognised for its importance in receptor assembly, trafficking and post-translational modifications, but its influence on extrasynaptic GABAA receptor function is less well understood. Here, we examine the pharmacological properties of a potentially native extrasynaptic AA receptor that incorporates the β1 subunit, specifically composed of α4β1δ and α4β1 subunits. Results: GABA activated concentration-dependent responses at α4β1δ and α4β1 receptors with EC50 values in the nanomolar to micromolar range, respectively. The divalent cations Zn2+ and Cu2+, and the β1-selective inhibitor salicylidine salicylhydrazide (SCS), inhibited GABA-activated currents at α4β1δ receptors. Surprisingly the α4β1 receptor demonstrated biphasic sensitivity to Zn2+ inhibition that may reflect variable subunit stoichiometries with differing sensitivity to Zn2+. The neurosteroid tetrahydro-deoxycorticosterone (THDOC) significantly increased GABA-initiated responses in concentrations above 30 nM for α4β1δ receptors. Conclusions: With this study we report the first pharmacological characterisation of various AA receptor ligands acting at murine α4β1δ AA receptors, thereby improving our understanding of the molecular pharmacology of this receptor isoform. This study highlights some notable differences in the pharmacology of murine and human α4β1δ receptors. We consider the likelihood that the α4β1δ receptor may play a role as an extrasynaptic AA receptor in the nervous system.

AB - Background: AA receptor subunit composition has a profound effect on the receptor's physiological and pharmacological properties. The receptor β subunit is widely recognised for its importance in receptor assembly, trafficking and post-translational modifications, but its influence on extrasynaptic GABAA receptor function is less well understood. Here, we examine the pharmacological properties of a potentially native extrasynaptic AA receptor that incorporates the β1 subunit, specifically composed of α4β1δ and α4β1 subunits. Results: GABA activated concentration-dependent responses at α4β1δ and α4β1 receptors with EC50 values in the nanomolar to micromolar range, respectively. The divalent cations Zn2+ and Cu2+, and the β1-selective inhibitor salicylidine salicylhydrazide (SCS), inhibited GABA-activated currents at α4β1δ receptors. Surprisingly the α4β1 receptor demonstrated biphasic sensitivity to Zn2+ inhibition that may reflect variable subunit stoichiometries with differing sensitivity to Zn2+. The neurosteroid tetrahydro-deoxycorticosterone (THDOC) significantly increased GABA-initiated responses in concentrations above 30 nM for α4β1δ receptors. Conclusions: With this study we report the first pharmacological characterisation of various AA receptor ligands acting at murine α4β1δ AA receptors, thereby improving our understanding of the molecular pharmacology of this receptor isoform. This study highlights some notable differences in the pharmacology of murine and human α4β1δ receptors. We consider the likelihood that the α4β1δ receptor may play a role as an extrasynaptic AA receptor in the nervous system.

U2 - 10.1186/s12868-015-0148-4

DO - 10.1186/s12868-015-0148-4

M3 - Journal article

C2 - 25887256

SN - 1471-2202

VL - 16

SP - 1

EP - 7

JO - B M C Neuroscience

JF - B M C Neuroscience

IS - 8

ER -