Stereologische Untersuchungen zur Gesamtneuronenzahl sowie der Kapillarlänge im Nucleus mediodorsalis des Thalamus bei Schizophrenie

The mediodorsal thalamic nucleus (MD) is the principal relay nucleus for the prefrontal cortex, a brain region thought to be dysfunctional in schizophrenia. Previous neuropathological studies on the MD in schizophrenia have yielded conflicting results and no clear pattern of alterations has yet been established in this subcortical region, possibly due to differences in quantitative histological methods used as well as differences in the investigated case series. While some studies suggested that patients with schizophrenia have a pronounced reduction of the volume and total neuron numbers in the MD, more recent data have not found anatomical alterations in this thalamic nucleus. Another possible key factor in the development of schizophrenia is the chronic fetal exposure to a hypoxic environment. It has been argued in earlier studies that a subtle metabolic deficit, such as hypoxia, would be sufficient to cause microvasculature abnormalities in the brain like an increase in capillary density. However, a recent study has not found changes in the capillary length density of the frontal cortex in schizophrenic patients. The present study investigated the MD in both hemispheres of 26 post mortem brains for volume, total neuron number and capillary length density with high-precision design-based stereology. The analysed case series consisted of 13 post-mortem brains from male schizophrenic patients (age range: 22 - 64 years; mean age 51.5 ± 3.3 years) and 13 age-matched male controls (age range: 25-65 years; mean age 51.9 ± 3.1 years). A general linear model univariate analysis of variance with diagnosis and hemisphere as fixed factors and age of the patients, post-mortem interval and fixation time as covariates showed a statistically significant light increase of the mean capillary length density. However, there were no other differences in volume, total neuron number, neuron density, capillary length and capillary length per neuron in the MD between the two groups. The rigorous quantitative analysis of this brain region is crucial to provide reliable information on the neuropathology of schizophrenia. Thus, alterations in total neuron number, volume and capillary length density in the MD cannot be considered a general feature of schizophrenia. The investigation of the microvasculature showed no sign of a chronic hypoxic influence on the MD