Using electrophysiological methods to measure electrical currents through cell membranes, the research group at the Institute for Physiology and Pharmacology, led by Marjan Slak Rupnik, showed that dextromethorphan extends the periods of electrical activity in beta cells. It is precisely during these periods, so-called bursts, that the cells secrete insulin.
The scientists demonstrated that, via so-called NMDA receptors, the active ingredient stimulated the pancreatic beta cells to secrete more insulin at raised blood sugar levels. This brought about an improvement in blood sugar, whilst at the same time reducing so-called sugar spikes, that is phases with particularly high blood glucose concentrations.
Also of benefit for type 1 diabetics
Slak Rupnik: "Our studies also indicate that the tested cough suppressant protects the beta cells from cell death, which would also be very beneficial for type 1 diabetics." Their diabetes worsens appreciably over the course of the illness so that – despite an improvement in blood sugar levels directly after the start of insulin therapy – they have a constantly high insulin requirement. This is thought to be due to the beta cells dying off or at least gradually producing less insulin, amongst other things. Further studies are now required to clarify whether the cough suppressant actually protects the beta cells if it is used in conjunction with conventional diabetes therapy.
The study was conducted as a collaborative project between MedUni Vienna (Center for Physiology and Pharmacology) and Heinrich Heine University, Düsseldorf, Düsseldorf University Hospital and the Institute for Beta-Cell Biology of the German Diabetes Center.
„Characterization of pancreatic NMDA receptors as possible drug targets for diabetes treatment.“ E. Lammert, J. Marquard , S. Otter , A. Welters , A. Stirban , J. Eglinger , D. Herebian , O. Kletke , M. Skelin Klemen , A. Stozer , S. Wnendt , L. Piemonti , M. Köhler , F. Schliess , M. Slak Rupnik , T. Heise , P. Berggren , N. Klöcker , T. Meissner , E. Mayatepek , D. Eberhard , M. Kragl , J. Ferrer, B. Thorens, A. Fischer. Nature Medicine, Feb 2015. DOI: 10.1038/nm.3822.