Galanin evokes a cytosolic calcium bursting mode and hormone release in GH3/B6 pituitary cells

Abstract The effects of galanin on secretion and cytosolic free Ca 2+ concentration ([Ca 2+ i ) have been studied in GH3/B6 pituitary cells. Prolactin (PRL) and growth hormone (GH) release was measured in column Perifusion experiments; [Ca 2+ ] i was monitored in single cells by dual emission microspectrofluorimetry using indo-1 as intracellular Ca 2+ probe. Galanin (0.1–1 nM) caused PRL and GH release coincident with a modest rise in [Ca 2+ ] i The increase in [Ca 2+ ] i comprises the establishment of characteristic long-lasting bursts of [Ca 2+ ] i transients. Galanin acts on Ca 2+ entry through voltage-gated Ca 2+ channels since there was no response to the peptide when Cd 2+ - a Ca 2+ channel blocker - was added to the bath solution. The stimulation of bursting activity by galanin may provide a fine Ca 2+ -signalling mechanism which maximally stimulates hormone release while avoiding refractory periods.