Estrogen deprivation associated with loss of dopamine cells

Estrogen deprivation leads to the death of dopamine cells in the brain, a finding by Yale scientists that could help explain why Parkinson’s disease is more likely to develop in men than in premenopausal women and why it increases in women after menopause.

“Without estrogen, more than 30 percent of all the dopamine neurons disappeared in a major area of the brain that produces the neurotransmitter dopamine,” said D. Eugene Redmond Jr., M.D., professor of psychiatry and neurosurgery and director of the Neural Transplantation and Regeneration Program.

The discovery was made after a team led by Redmond removed the ovaries of female monkeys, thereby depleting their bodies of estrogen and other gonadal hormones. Within 10 days, key neurons in the brain that protect against Parkinson’s disappeared. After 30 days the cells appeared to be permanently lost. The scientists were able to regenerate the cells by administering estrogen within 10 days.

Redmond said monkeys were used in the study because they have menstrual cycles and many other close similarities to humans. The researchers were interested in sexual differences in dopamine neurons in the substantia nigra area of the midbrain, whose destruction is associated with Parkinson’s disease and dementia.

The study was published in the December issue of The Journal of Neuroscience. The principal investigator was Csaba Leranth, M.D., Ph.D., professor of obstetrics and gynecology and of neurobiology.