Large neurons in the tuberomammillary nucleus in patients with Parkinson's disease and multiple system atrophy

To investigate whether the histaminergic neurons degenerate in Parkinson's disease (PD) and multiple system atrophy (MSA), we studied the number of large-sized neurons in the tuberomammillary nucleus in patients with PD, patients with MSA, and age-matched controls. The number of large-sized neurons in the tuberomammillary nucleus in PD patients was not altered compared with controls, and Lewy bodies were rarely present in the tuberomammillary nucleus. In contrast, the number of large-sized neurons in the tuberomammillary nucleus in MSA patients was significantly decreased compared with controls. Thus, the central histaminergic neurons are affected in MSA and preserved in PD.