Ionising radiation triggers fat accumulation in white adipose tissue

Abstract

Purpose: To investigate changes in gonadal white adipose tissue and lipogenesis-related gene expression induced by radiation exposure.

Materials and methods: Groups of two-month-old C57BL/6 mice were exposed whole-body to ¹³⁷Cs γ-rays at a single dose (5 gray [Gy]) or fractionated doses (1 Gy × 5 times, 0.5 Gy × 10 times, or 0.2 Gy × 25 times). Six months after irradiation, gonadal white adipose tissue was isolated from mice. Two and 25-month-old mice were used as young and old study references. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was used to measure messenger RNA (mRNA) expression of genes related to: (i) Primary lipid metabolism (ATP-citrate lyase [ACL], malic enzyme1 [ME1] and glucose-6-phosphate dehydrogenase 2 [G6PD2]), (ii) glucose uptake (glucose transporter 4 [GLUT4]), (iii) fatty acid synthesis (sterol regulatory element binding transcription factor 1 [SREBP-1c], fatty acid synthetase [FAS] and acetyl-coenzyme A carboxylase beta [ACC]), (iv) triglyceride synthesis (diacylglycerol O-acyltransferase 1 [DGAT1] and diacylglycerol O-acyltransferase 2 [DGAT2]), and (v) adipose-derived hormones (leptin [LEP]).

Results: The weight of gonadal white adipose tissue in the irradiated groups tended to increase compared to the non-irradiated group though the radiation-induced increase in white adipose tissue was only significant for the 5 × 1 Gy group. The mRNA levels of SREBP-1c, ACC, FAS, ACL, GLUT4, ME1 and G6PD2 were relatively lower in γ-irradiated groups than in non-irradiated groups. The mRNA levels of leptin and DGAT were relatively higher than non-irradiated groups. The changes in expression of these lipogenesis-related genes caused by γ-irradiation showed a very similar pattern to changes caused by ageing.

Conclusions: A physical agent such as γ-rays can trigger biological responses resulting in fat accumulation of gonadal white adipose tissue in mice.

Keywords:

• ionisng radiation
• γ-irradiation
• gonadal white adipose tissue
• lipogenesis
• fat accumulation
• real-time RT PCR

Acknowledgements

The authors would like to express their thanks to Ms Eun-Hee Cho, Mr Hyeon-Soo Eom, Ms Seolhwa Kim, and Ms Seol-Hee Hong for technical assistance in this work. This work was supported by grant no. 2010-0005282 from Nuclear R&D Program of Ministry of Education, Science and Technology, Republic of Korea

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.