Modulation of alpha-crystallin chaperone activity in diabetic rat lens by curcumin

Mol Vis. 2005 Jul 26;11:561-8.

Abstract

Purpose: A decline in the chaperone-like activity of eye lens alpha-crystallin in diabetic conditions has been reported. In this study, we investigated whether curcumin, a dietary antioxidant, can manipulate the chaperone-like activity of alpha-crystallin in diabetic rat lens.

Methods: A group of rats received ip injection of streptozotocin (STZ; 35 mg/kg body weight in buffer) to induce hyperglycemia, while another group of rats received only buffer as vehicle and served as control. STZ-treated rats were assigned to 3 groups and fed either no curcumin or 0.002% or 0.01% curcumin, respectively. Cataract progression due to hyperglycemia was monitored with a slit lamp biomicroscope. At the end of 8 weeks animals were sacrificed and lenses were collected. alphaH- and alphaL-crystallins from a set of pooled lenses in each group were isolated by gel filtration. Chaperone activity, hydrophobicity, and secondary and tertiary structure of alphaH- and alphaL-crystallins were assessed by light scattering/spectroscopic methods.

Results: A decrease in chaperone-like activity of alphaH- and alphaL-crystallins was observed in STZ-treated diabetic rats. The declined chaperone-like activity due to hyperglycemia was associated with reduced hydrophobicity and altered secondary and tertiary structure of alphaH- and alphaL-crystallins. Interestingly, alphaH- and alphaL-crystallins isolated from curcumin fed diabetic rat lenses had shown improved chaperone-like activity as compared to alphaH- and alphaL-crystallins from untreated diabetic rat lens. Feeding of curcumin prevented the alterations in hydrophobicity and structural changes due to STZ-induced hyperglycemia. Modulation of functional and structural properties by curcumin was found to be greater with the alphaL-crystallin than alphaH-crystallin. Loss of chaperone activity of alpha-crystallin, particularly alphaL-crystallin, in diabetic rat lens could be attributed at least partly to increased oxidative stress. Being an antioxidant, curcumin feeding has prevented the loss of alpha-crystallin chaperone activity and delayed the progression and maturation of diabetic cataract.

Conclusions: We demonstrate that curcumin, at the levels close to dietary consumption, prevented the loss of chaperone-like activity of alpha-crystallin vis-a-vis cataractogenesis due to diabetes in rat lens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antioxidants / administration & dosage
  • Blood Glucose / analysis
  • Body Weight
  • Cataract / metabolism*
  • Cataract / physiopathology
  • Chromatography, Gel
  • Circular Dichroism
  • Curcumin / administration & dosage*
  • Diabetes Mellitus, Experimental / metabolism*
  • Diet
  • Hyperglycemia / metabolism*
  • Hyperglycemia / physiopathology
  • Lens, Crystalline / metabolism*
  • Male
  • Molecular Chaperones / metabolism*
  • Rats
  • Spectrometry, Fluorescence
  • alpha-Crystallins / metabolism*

Substances

  • Antioxidants
  • Blood Glucose
  • Molecular Chaperones
  • alpha-Crystallins
  • Curcumin