The purpose of this work was to compare the influences of
sulforaphane (SFN) to those of the standard
insulin sensitizer
pioglitazone (PIO) on high
fructose diet (HFrD)-induced
insulin resistance,
dyslipidemia, hepatosteatosis, and vascular dysfunction in rats. Male Sprague Dawley rats (150-200 g) were fed on a standard diet (control) or a high
fructose diet (HFrD, 60% w/w
fructose) for 60 days. From day 16, two subgroups of HFrD-fed rats received either SFN (0.5 mg/kg/day, orally) or PIO (5 mg/kg/day, orally) along with HFrD until the end of the experiment.
Fructose-fed rats showed significant decreases in food intake,
body weight and feeding efficiency; effects that were not altered by either treatment. Data from
insulin tolerance test (ITT), oral
glucose tolerance test (OGTT), and HOMA-IR and HOMA-β indices demonstrated impaired
insulin sensitivity and
glucose utilization in HFrD-fed rats. SFN and PIO treatments significantly reduced OGTTAUC (Glass's Delta values = 1.12 and 0.84, respectively), decreased ITTAUC (Glass's Delta values = 1.05 and 0.71, respectively), significantly diminished HOMA-IR index (by 55.6% and 77.6%, respectively), and increased HOMA-β value (by 1.8 and 1.3 fold, respectively) compared to the HFrD rats. Moreover, SFN and PIO ameliorated hepatic oxidative stress and reduced serum levels of
C-reactive protein and
lactate dehydrogenase in HFrD-fed rats. Furthermore, SFN and PIO administrations improved
insulin resistance-associated heaptosteatosis and enhanced vascular responsiveness to
acetylcholine-induced relaxations. However, only SFN was able to enhance serum HDL-C levels in HFrD group. These finding suggests that SFN elicited
insulin-sensitizing, hepatoprotective, and vasculoprotective effects in HFrD
insulin-resistant rats that were comparable to those exerted by PIO.