Day-night variations in pro-oxidant reactions of hypothalamic, hepatic and pancreatic tissue in mice with spontaneous obesity (Neotomodon alstoni)

Abstract

Objectives: The present work compares the pro-oxidant properties in hypothalamic, hepatic, and pancreatic tissue of spontaneously obese and lean Neotomodon alstoni during day and night. Methods: Lipid peroxidation from hypothalamus, liver, and pancreas from lean and obese mice were quantified by the two-thiobarbituric acid method. Lipid peroxidation in vivo was also determined by means of detection of conjugated dienes in lipid extracts. Results: Hypothalamic tissue from obese Neotomodon showed a notorious increase (nearly 700%) in the production of thiobarbituric acid-reactive substances (TBARS) at day, either in basal as well as in an assay supplemented with Fe²⁺; the presence of conjugated dienes was also notably greater (76%) at day. Hypothalamus of lean mice presented an increase (170%) in assay supplemented with Fe²⁺. Hepatic tissue in obese mice showed diurnal increasing in TBARS + Fe²⁺ (34%) and in conjugated dienes (38%), while lean mice showed only a diurnal increase (45%) in TBARS + Fe²⁺. Pancreatic tissue from obese mice presented a diurnal increasing in basal TBARS (130%) but a decrease (72%) in TBARS + Fe²⁺. Presence of conjugated dienes was also decreased during the day in lean (60%) and in obese (40%) mice. Conclusions: In the obese Neotomodon, there is a larger day–night change in pro-oxidant status in the hypothalamus and in pancreas than the one observed in the liver, suggesting a differential equilibrium between oxidative reactions and antioxidant defenses in the different tissues during the day–night cycle.

Keywords:

• thiobarbituric acid-reactive substances
• conjugated dienes
• obesity
• day–night changes
• Neotomodon alstoni
• hypothalamus
• liver
• pancreas

Acknowledgements

The authors thank Dr Dorothy Pless for review of the English version of this manuscript. Also we thank Lic. Nut. Fernando López-Barrera for her helpful assistance. PMM was supported by postdoctoral fellowship DGAPA.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work was supported by DGAPA-PAPIIT grants to MMA [grant number IN212715]; MDM [grant number IN202412].