Sibutramine metabolites increase glucose transport by cultured rat muscle cells.
BACKGROUND
The anti-obesity agent sibutramine, a serotonin and noradrenaline reuptake inhibitor (SNRI), has been shown to reduce insulin resistance and improve glycaemic control in obese-diabetic ob/ob mice and overweight type 2 diabetic patients.


OBJECTIVE
To investigate whether sibutramine or its metabolites act directly on muscle cells to improve glucose uptake and insulin action.


METHODS
Uptake of the non-metabolized glucose analogue 2-deoxyglucose was measured in cultured L6 rat muscle cells after incubation with sibutramine, its two pharmacologically active metabolites and related agents.


RESULTS
Sibutramine itself (10(-8)-10(-6) M) did not significantly affect 2-deoxyglucose uptake during incubations up to 72 h. The primary amine metabolite M2 (10(-7) and 10(-6) M) increased basal and insulin-stimulated 2-deoxyglucose uptake (by 12% and 34%) after 24 h incubation. These effects of M2 were lost by 72 h incubation. However, the secondary amine metabolite M1 (10(-6) M) increased basal and insulin-stimulated 2-deoxyglucose uptake (by 50%) after 72 h incubation, although M1 was ineffective after 24 h. M2 stimulated 2-deoxyglucose uptake in the presence of LY-294,002 (an inhibitor of phosphatidylinositol 3-kinase) but the effect of M2 was inhibited by cytochalasin B, which acutely blocks glucose transporters. Incubations with serotoninergic, noradrenergic and dopaminergic agents, or agents known to stimulate release or inhibit reuptake of these substances in nervous tissues indicated that the sibutramine metabolites were not affecting 2-deoxyglucose uptake via mechanisms associated with their SNRI properties.


CONCLUSIONS
Sibutramine metabolites can improve insulin-sensitive 2-deoxyglucose uptake by cultured muscle cells independently of SNRI effects.
Bailey
C J
CJ
School of Life and Health Sciences, Aston University, Birmingham, UK, UK.
Turner
S L
SL
Bates
S H
SH
Jones
R B
RB
D000818:Animals; D001067:Appetite Depressants / Q000378:metabolism / Q000494:pharmacology*; D019540:Area Under Curve; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D003503:Cyclobutanes / Q000378:metabolism / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D003847:Deoxyglucose / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D009025:Morpholines / Q000494:pharmacology; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
D001067:Appetite Depressants; D002867:Chromones; D003503:Cyclobutanes; D004791:Enzyme Inhibitors; D007328:Insulin; D009025:Morpholines; D011500:Protein Synthesis Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D003571:Cytochalasin B; D003513:Cycloheximide; D003847:Deoxyglucose; D005947:Glucose; C058254:sibutramine