| Research Abstract |
Using monoamine oxidase (MAO) histochemistry, we have demonstrated the topographical distributions of MAO-containing neurons in the human hyopothalamus. In the human hypothalamus, MAO-containing neurons were mostly of a magnocellular type. They were located in the caudal two-thirds of the human hypothalamus. These MAO-containing neurons appeared to correspond to the histaminergic neurons in this region, judging based on the similarities of the topographical distributions and morphological apearances (Nakamura et al., Neuroscience, 1991 ; Panula et al., Neuroscience, 1991). A omparison of topographic maps of MAO-containing neruons in the human hypothalamus and Nissl-stained paraffin sections made us to localize the presumptive histaminergic neurons of TM in Nissl-stained sections of patients with Alzheimer's disease (AD) and normal controls (Nakamura et al., Neurosci.Lett., 1993). We found the frequent occurrences of neruofibrillary tangles in the large-sized neurons in TM of patients w
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ith AD.In addition, the number of large-sized neurons in TM of AD was smaller than that of age-matched controls. These results suggested that the central histaminergic system is involved in AD.To determine the possible involvements of the central histaminergic system in other neurodegenerative diseases, we examined TM of Parkinson's disease (PD) and multiple system atrophy (MSA) by the similar quantitative method. In contrast of AD, the neuron number of TM of PD was not altered compared to age-matched controls (Nakamura et al., Can.J.Neurol.Sci.Suppl.4, 1993). Thus, it is suggested that the central histaminergic system is preserved in PD.However, the number of large neruons in TM of MSA was decreased compared to age-matched controls.
The central histaminergic system has been shown to be associated with the regulation of the sleep-wake cycle. Therefore, the involvements of histaminergic neurons in AD and MSA found in the present stuies may be an anatomical basis for the sleep-wake distubances frequently observed in the diseases. Less
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