GABAA receptor-mediated currents and hormone mRNAs in cells expressing more than one hormone transcript in intact human pancreatic islets

In pancreatic islets the major cell-types are α, β and δ cells, secreting the hormones glucagon (GCG), insulin (INS) and somatostatin (SST), respectively. The GABA (γ-aminobutyric acid) signalling system is expressed in human pancreatic islets. We have previously used single-cell RT-PCR in combination with current recordings to correlate expression of single hormone transcript with functional GABA A receptor (iGABA A R) properties in islets. Here we extended these studies to islet cells from non-diabetic and type 2 diabetic donors that express mRNAs for more than one hormone. We detected cells expressing double (α/β, α/δ, β/δ cell-types) and triple (α/β/δ cell-type) hormone transcripts. The most common mixed-identity cell-type was the α/β group where the cells could be grouped into β- and α-like subgroups. The β-like cells had low hormone transcript GCG / INS expression ratio ( A R openings than the α-like cells where the GCG / INS expression ratio was high (> 1.2). The difference in expression levels and single channel iGABA A R characteristics varied in the α/β/δ cell-type. No correlation was observed between the cell-types identity with time in culture or cell size. Clearly, multiple hormone transcripts can be expressed in islet cells whereas iGABA A R functional properties appear α or β cell specific.