Pancreatic α-cells are functionally heterogeneous and sex-dependently regulated by neighboring endocrine cells

Glucose and paracrine regulation of α-cells, particularly with respect to sex differences, is still poorly understood. Here, we imaged islets from GluCre:GCaMP6f mice in pancreatic slices, additionally loaded with a red Ca²⁺ indicator, to precisely interrogate Ca²⁺ dynamics in α-cells and the adjacent β- and δ-cells. During a glucose ramp (1.8-10.8 mM), α-cell Ca²⁺ oscillations were heterogeneous, antiphasic to β-cells, and inversely correlated with δ-cells. Selective inhibition of insulin receptor (InsR) and somatostatin receptor subtypes-2 and 3 (SSTR2/3) shifted the majority of α-cells to hyperactivity, delayed the decline of α-cell activity and onset of β-cell Ca²⁺ oscillations during the ramp. While female α-cells exhibited greater sensitivity to SSTR2/3 inhibition, male α-cells were more responsive to InsR blockade. Under complete SSTR2/3 and InsR antagonism, α-cells exhibited elevated Ca²⁺ oscillations but remained glucose-dependent. We conclude that intra-islet coordination fine-tunes α-cell glucose responses, with sex-specific paracrine signaling potentially shaping glucagon profiles in metabolic disease.