In Vivo Assessment of Mouse Hindleg Intramyocellular Lipids by ¹H-MR Spectroscopy

Rationale and Objectives

¹H-magnetic resonance spectroscopy (¹H-MRS) has proved to be the sole in vivo technique able to measure intramyocellular lipids (IMCL) in both humans and animals. Mouse models are now widely used for physiologic studies and drug discovery. However, IMCL assessment using ¹H-MRS is hindered in this animal model by the small muscle size and strong contamination from the extramyocellular lipid (EMCL) signal. The objective of this study was to the use of ¹H-MRS for IMCL quantification in mice at different ages.

Materials and Methods

Noninvasive IMCL quantification was performed at 7 T in tibialis anterior (TA) muscles of healthy male C57/BL6 mice (n = 9; age, 13.6 ± 1 months), db/db mice (n = 4), and their C57BL/KSJ control littermates (n = 4) at 7 and 17 weeks of age.

Results

The IMCL content of diabetic mice TA was significantly higher than their littermates (2.41 ± 0.5 vs. 1.21 ± 0.35, P < .01). An age effect was observed, with TA IMCL levels being lower in older than younger control mice, but increasing between 7 and 17 weeks in the db/db mice.

Conclusions

The feasibility of ¹H-MRS spectroscopy was demonstrated in mice muscle, despite its small size, and used to assess IMCL content in db/db mice.

Key Words: ¹H-MR spectroscopy, IMCL, EMCL, skeletal muscle, db/db mice