This animal study used synchrotron X-ray fluorescence to map rubidium in nine brain regions involved in appetite in rats made obese with a high-calorie diet and in lean controls. Rubidium was higher in every region in the obese rats, by about 35% to 72%. The authors state, from their earlier work, that the obese rats took in less rubidium from the diet, so the rise is not explained by intake.
Key numbers
- Rubidium surface mass higher in obese than lean rats in all nine regions (each p below 0.01) (Results, p. 5).
- Relative increase in obese rats: about 72% in orbitofrontal cortex, 46% in posterior lateral hypothalamus, 44% in ventromedial hypothalamus and 35% in amygdala (Results, p. 5; Figure 4).
- Detection limit for rubidium 0.000623 ± 0.000049 µg/cm2; all measured values exceeded it (Results, p. 5).
- Absolute rubidium values are shown only in Figure 3 and are not tabulated.
Methods (brief)
Sixteen male Wistar rats (8 obese after 54 days of a high-calorie diet, 8 lean) from an earlier study; 20 µm cryosections; synchrotron X-ray fluorescence at the POLYX beamline (15.4 keV) with thin-film calibration standards; t-tests, nonparametric ANOVA and principal component analysis.
Evidence fitness
Context only: supports a mechanistic observation that brain rubidium is higher in diet-induced obese rats. It does not support dietary exposure, food concentrations, human toxicity or any limit.
Limitations
Small animal study, males only; values are surface mass per area of thin sections, not tissue concentrations per mass; diet rubidium content is referenced to earlier work rather than reported here.
Related evidence
Update history
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