Effect of chronic jet lag after induction of Dalton's lymphoma in male and female mice

Abstract

Biological rhythms are ubiquitous phenomena that enable an organism to temporally adapt to the environment. Jet lag occurs during rapid transmeridial transport and disrupts the normal biological rhythm. Disruption of the biological rhythm is known to reduce survival and hasten tumorigenesis in male mice. Dalton's lymphoma (DL) is a spontaneous and highly invasive T-cell lymphoma that develops as an ascitic tumor in murines. DL was induced by serial implantation of live ascite cells in laboratory-acclimated age-matched male and female AKR mice. The mice were then subjected to simulated chronic jet lag (CJL) by rapidly and alternately advancing and delaying the ambient light dark cycle by 8 h every 2 days. Females, but not males, with DL became arrhythmic after exposure to simulated CJL. Survival was significantly curtailed in both male and female mice with DL + CJL compared to survival in mice with DL alone or CJL alone (∼16 days after DL induction in mice and facing jet lag, and ∼28 days after DL induction in mice bearing but not undergoing jet lag simulation). These results suggest that female mice may be more at risk from jet lag associated effects if they have cancer prior to facing jet lag, and DL + CJL may detrimentally impact the female circadian clock more than that of the males.

Keywords:

• circadian rhythm
• cancer
• Dalton's lymphoma
• chronic jet lag

Acknowledgments

The authors gratefully acknowledge financial aid to MS by Banaras Hindu University vide grant no. F(A) 1–14 (G)/3449 and Research Fellowship grant to PB by the CSIR-UGC, Govt. of India. The fellowship to RT under UGC-RFMS is gratefully acknowledged. The authors are thankful to Mr Varun Kumar Pandey for his help during maintenance of the experiment.