Effect of muscimol on glucose-stimulated somatostatin and insulin release from the isolated, perfused rat pancreas.
This study examines the effect of muscimol, a high affinity, specific gamma-aminobutyric acid (GABA) agonist, on glucose-stimulated somatostatin and insulin release from the isolated, perfused rat pancreas. Perfusion with low glucose (50 mg/dl) conditions resulted in basal somatostatin release of 46 +/- 4 pg/ml. Basal insulin release was less than 20 microU/ml. High glucose (300 mg/dl) conditions stimulated somatostatin and insulin release. Steady-state levels of somatostatin and insulin release under high glucose conditions were 425 +/- 12 pg/ml and 419 +/- 18 microU/ml, respectively. Perfusion with medium containing 1 microM muscimol inhibited glucose-stimulated somatostatin release by 38%, whereas the course of glucose-stimulated insulin release was unaffected. Tentative conclusions from this study are (1) that GABA is potentially a modulator of islet somatostatin but not insulin release, and (2) the fact that somatostatin, an inhibitor of insulin, can be suppressed 38% without coincidental increase in insulin release seems to indicate that, under high glucose conditions, somatostatin is without a significant paracrine effect on the beta-cells.
D000818:Animals; D005947:Glucose / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D008297:Male; D009118:Muscimol / Q000494:pharmacology*; D010080:Oxazoles / Q000494:pharmacology*; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D013004:Somatostatin / Q000378:metabolism*
D007328:Insulin; D010080:Oxazoles; D009118:Muscimol; D013004:Somatostatin; D005947:Glucose