Effect of Oligonucleotide IMT504 in a Type I Diabetes Model Induced by Multiple Low Doses of Streptozotocin in Mice.

BIANCHI MS,; CALVO V,; CHASSEING NA.; LIBERTUN C,; MONTANER A; LUX-LANTOS V.

Boston, Massachusetts

Congreso; ENDO 2011: The 93rd Annual Meeting & Expo.; 2011

Endocrine Society.

IMT504, the prototype of the PyNTTTTGT class of oligonucleotides, stimulates mesenchymal stem cells both in vitro and in vivo (1). We have shown that the oligonucleotide IMT504 induces a marked recovery of single-dose streptozotocin (STZ)-induced toxic diabetes in male rats that correlates with early expression of progenitor cell markers (2). Here, we evaluated the effect of IMT504 administration on a type I diabetes model induced by multiple low doses of STZ in mice. Male Balb/C mice (6-8 week-old) were injected with STZ ip (40mg/kg, diluted in citrate buffer) daily for 5 consecutive days or with citrate buffer as control (C). Normal glycemia (Gly) in the fed condition was 149+/-13 mg/dl. Animals which developed Gly levels mayor 250 mg/dl were considered diabetics and injected daily with IMT504 doses (20mg/kg/day, sc) for 10 days (STZ-IMT) or saline as control (STZ) (day 1). Another 5 doses of IMT504 starting on days 21 and 36 were then administrated. A group of C mice were injected with the same IMT doses (C-IMT).Body weight was recorded and Gly was measured for a total of 66 days. At the end of the experiment, glucose tolerance tests (GTT) were performed (2g/kg BW glucose was injected ip, and glucose determined in tail blood samples). Four days later fasted animals were sacrificed, blood samples and pancreases collected for hormonal determinations and histological studies respectively. We observed that 20% of STZ mice (2/10) showed spontaneous reversion of the diabetic condition whereas IMT treatment induced a marked blood glucose decrease in 88% of STZ-IMT-treated mice (7/8) [day 66= Gly (mg/dl): C: 130+/ -9 (n=6) vs STZ-IMT: 278+/-46, p=0.01, STZ-IMT vs STZ: 557+/ -20, p=0.01]. GTTs showed a partial recovery in the STZ-IMT responsiveness [ANOVA: p=0.001, 0 min= C: 117+/-11, STZ-IMT: 164+/-, STZ: 309+/-53, STZ vs C and STZ-IMT: p=0.02; 30 min= C: 292+/-51, STZ-IMT: 342+/-33, STZ: 488+/-36, C vs STZ: p=0.02; 120 min C: 133+/-15, STZ-IMT: 352+/-28, STZ: 472+/-52, C vs STZ and vs STZ-IMT: p=0.02]. Regarding body weight, IMT promoted a transient decrease in STZ mice. Besides IMT improved beta cell function in diabetic animals [HOMA beta cell= C: 66+/-29, STZ-IMT: 46+/-8, STZ: 13+/-5, ANOVA: p=0.01, STZ vs C and vs STZ-IMT: p=0.03]. Histomorphological analysis of pancreatic sections showed severe decreases in islets number from STZ mice, while a recovery was observed in islets from STZ-IMT animals, supporting our findings. IMT504 improves the diabetic condition in this model of type I diabetes.