Probiotics and Curcumin Did Not Alter Low-Dose Streptozotocin-Induced Hyperglycemia and Oxidative Stress in a Rat Model.

Abstract

This study aimed to investigate the individual and combined effects of the multi-strain probiotic VSL#3 and curcumin on glycemic control, insulin resistance, and oxidative stress (OS) in a rat model of T2DM induced by a high-fat diet (HFD) and streptozotocin (STZ). Forty male Sprague-Dawley rats were divided into five groups: negative control, positive control (PC) induced with HFD and STZ, VSL#3 probiotic (PRO) (2.5 × 10¹⁰ CFU/day VSL#3), curcumin (CUR) (200 mg/kg/day curcumin), and combination of VSL#3 and curcumin (PRO+CUR) (2.5 × 10¹⁰ CFU/day VSL#3 + 200 mg/kg/day curcumin). At the end of 8 weeks, the study assessed the effects of these interventions on body weight, food intake, fasting blood glucose, and insulin resistance (HOMA-IR). Additionally, serum and pancreatic tissue antioxidant parameters, were measured, including TAC, SOD, CAT, GP<i>x</i>, and MDA. VSL#3 and curcumin individually improved body weight, fasting blood glucose, and antioxidant enzyme activities. The PRO+CUR group showed the highest body weight gain and lower fasting blood glucose (353.83 ± 39.48 mg/dL) compared to the PC group (<i>p</i> < 0.05). However, the PRO+CUR combination did not yield the expected synergistic effects, likely due to curcumin's low bioavailability and prooxidant effects. Serum TAC was highest in the CUR group (0.78 ± 0.05 U/ng), whereas the PRO+CUR group showed reduced TAC (0.16 ± 0.02 U/ng). HOMA-IR values increased in the PRO and CUR groups, but no significant change was observed in the PRO+CUR group. This study demonstrates the therapeutic potential of probiotics and curcumin in T2DM. Probiotics enhanced antioxidant defenses and reduced OS, but the combination with curcumin showed no synergistic effects, likely due to curcumin's bioavailability.