Profiling of GABA and GABA receptor expression in the myometrium of the human uterus.

AIMS

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.

MAIN METHODS

The expression levels of the 19 GABAR subunits (α-α, β-β, γ-γ, δ, ε, π, θ, ρ-ρ) and the three GABAR subunits (GABA, GABA, GABA) were characterized by RT-qPCR analysis on two commercial samples and six samples derived from surgically removed myometrial tissues from different women. We probed for functional GABAR expression in primary human myometrial smooth muscle cells (HMSMCs) by whole-cell patch-clamp electrophysiology.

KEY FINDINGS

The absolute mRNA levels of the 22 GABAR and GABAR genes varied considerably across the eight samples, but a pronounced overlap existed between the specific subunits detected in the samples, with α, β, β, ε, π, θ, GABA and GABA mRNAs being detected in most samples. The expression profile of GABAR and GABAR subunit mRNAs in HMSMCs correlated with that observed in the eight tissue samples, albeit the subunit transcripts were detected at lower relative levels. Neither muscimol nor GABA evoked significant currents in these cells in the patch-clamp recordings.

SIGNIFICANCE

While the expression of the GABA subunits on their own is unlikely to give rise to functional GABAR expression, the GABAR subunits identified at mRNA level would be able to form functional receptors in the human myometrial tissue. Although GABAR-mediated currents could not be recorded from HMSMCs in this study, this suggests a role for GABAergic transmission in the human myometrium.