Gender-related changes in increase of dopaminergic neurons in the olfactory bulb of Parkinson's disease patients.

Gender differences in dopaminergic related neurodegenerative diseases have hardly been studied until now. It is generally accepted that more men than women suffer from Parkinson's disease. One of the most prevalent symptoms in Parkinson's patients, hyposmia, does not show gender differences, while normally the sense of smell is better developed in females. Whether the change in dopamine in the olfactory bulb contributes equally to hyposmia in male and female Parkinson's patients is the subject of the present study. In a stereological study the total number of tyrosine hydroxylase immunoreactive neurons in the olfactory bulbs of male and female Parkinson's patients and age-matched controls has been estimated. The present stereological study shows that the number of tyrosine hydroxylase positive cells in control females is significantly lower than those in control males. The number of dopaminergic cells in the olfactory bulbs of both male and female Parkinson's patients equals that of healthy males of the same age group. We therefore conclude that the hyposmia in Parkinson's disease patients cannot simply be ascribed to dopamine in the olfactory bulb.