A post-mortem stereological study of striatal cell number in human obesity

OBJECTIVE: Neuroimaging studies have revealed abnormalities in brain structure, including the striatum, in obese people. We aimed to investigate the cellular and parenchymal basis for these findings in post-mortem brain tissue. DESIGN AND METHODS: Design-based (unbiased) stereology combined with histochemical and immunocytochemical staining were used to quantify total number of neurons and astrocytes in post-mortem striatal brain samples from 9 obese (BMI 40.2±6.1 kg*m(−2)) and 8 lean (BMI 24.4±1.0 kg*m(−2)) donors. Total numbers of Nissl-stained neurons and GFAP-immunopositive astrocytes were counted in ten systematic-random sections starting from the frontal pole of the striatum. RESULTS: There were no differences in mean total numbers of neurons (obese: 7.60E+06; SD 2.50E+06; lean: 7.85E+06; SD 8.26E+05; p<0.78) or astrocytes (obese: 7.42E+06; SD 2.27E+06; lean: 7.43E+06; SD 2.50E+06; p<0.99). A higher variance was found for number of neurons (p<0.007) but not astrocytes (p<0.72) in the obese group. Neuron/glia ratios were similar in both groups (obese: 1.07; SD 0.39; lean: 1.15; SD 0.37; p<0.70) with an overall striatal neuron/glia ratio of 1.11 (SD 0.37) across the entire study population (n=17). CONCLUSION: We found no difference in the average numbers of neurons and astrocytes in the anterior striatum between lean and obese people. The morphological basis for structural brain changes in obesity requires further investigation.