Effects of acute ovarian hormone suppression on the human brain: an in vivo 1H MRS study

A previous proton magnetic resonance spectroscopy ((1)H MRS) study carried out by our group indicated that post-menopausal women who started taking oestrogen therapy (ET) at or around the menopause had a significantly lower choline (Cho) concentration in the hippocampus and parietal lobe than those who were ET naïve, suggesting that long-term ET positively modulates neuronal/glial membrane turnover in older females. The objective of the current study was to determine whether neuronal membrane turnover is modulated by sex hormones in younger women following a pharmacologic challenge that induced acute ovarian hormone suppression. We carried out an in vivo(1)H MRS study in a group of 10 premenopausal women pre- and post-8 weeks of acute ovarian suppression with a Gonadotrophin Releasing Hormone analogue (GnRHa) (two Zoladex 3.6 mg implants). We report that young women, post-ovarian suppression, had a significant increase in Cho concentration (and Cho/Cr ratio) in the dorsolateral prefrontal cortex (DLPFC). They also showed a trend to a significant increase in Cho concentration in the hippocampus. This supports our previous findings and adds to the evidence that neuronal/glial membrane metabolism is affected by sex hormones in women.