Effects of S 15511, a therapeutic metabolite of the insulin-sensitizing agent S 15261, in the Zucker Diabetic Fatty rat.
OBJECTIVE
S 15261 is a novel oral antihyperglycaemic drug with both insulin secretagogue and insulin-sensitizing effects. The study was designed to determine the biological activity of its two major metabolites, S 15511 and Y 415, and whether or not they have an additive effect.


METHODS
Zucker Diabetic Fatty rats were treated for 28 days with S 15511 (10 mg/kg), Y 415 (10 mg/kg), or a combination at the same doses for a period of 4 weeks starting at 6-7 weeks of age. An additional group was pair-fed to the level of S 15511-treated animals to determine if possible effects were due to reduced food intake.


RESULTS
S 15511 alone and combined with Y 415 reduced energy intake and weight gain (-13% vs. controls; both p < 0.01). Baseline fasting plasma glucose levels were maintained by S 15511, S 15511 + Y 415 and pair-feeding (p < 0.01) for the entire treatment period (p < 0.01). Baseline insulin was maintained by pair-feeding only, whereas all other treated groups became hyperinsulinaemic (+110-276%; p < 0.05). Deterioration in insulin sensitivity [homeostasis model assessment (HOMA)-IR: + 239%; p < 0.01] was attenuated by S 15511, S 15511 + Y 415 and pair-feeding (p < 0.01) and was compensated for by improved insulin secretion (HOMA-beta; p < 0.01). Oral glucose tolerance tests, performed on days 0, 14 and 28, showed that all groups had an impaired insulin response, but by day 28, S 15511, S 15511 + Y 415 and pair-feeding had improved glucose disposal compared to the progressive deterioration in untreated controls (-44% to -48% vs. controls; p < 0.01), associated with progression to frank diabetes in these animals.


CONCLUSIONS
Treatment with these agents in a genetic model of type 2 diabetes reveals that they all have a transient effect compared to the progressive worsening of vehicle-treated controls. The improvements in glucose metabolism observed with S 15511 are significant, however, suggesting it has more therapeutic activity than the Y 415 metabolite of S 15261. It is associated with less frequent progression to diabetes; i.e. Y 415 exerts a non-significant effect alone and no significant additive effect when combined with S 15511. The mechanism of action of S 15511 may be via increased insulin sensitivity and beta-cell response preservation up to day 21. Thus, previously reported insulin secretagogue effects are likely to be attributable to the parent compound.
Pickavance
L C
LC
Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool, UK. lucyp@liverpool.ac.uk
Wilding
J P H
JP
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D050218:Body Fat Distribution; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D004435:Eating / Q000187:drug effects; D005449:Fluorenes / Q000378:metabolism / Q000627:therapeutic use*; D005951:Glucose Tolerance Test; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D051381:Rats; D011924:Rats, Zucker; D015430:Weight Gain / Q000187:drug effects
D001786:Blood Glucose; D005449:Fluorenes; D007004:Hypoglycemic Agents; D007328:Insulin; C518830:S 15511; C518831:Y 415 compound; C091921:S 15261