This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
Abstract
Objective: To determine whether there are menstrual cycle–related effects on cortical excitability in normal women.
Background: Ovarian steroid hormones affect neurotransmission in the brain. Data from animal experiments have shown that progesterone metabolites enhance the action of gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the cortex, producing benzodiazepine-like (e.g., diazepam and lorazepam) physiologic and behavioral effects. Estradiol has excitatory effects on measures of neuronal excitability, possibly acting through the glutamate system. These effects have been difficult to detect in women using conventional techniques. However, recently, paired transcranial magnetic stimulation (TMS) has been used to detect the effects of GABAergic and glutamatergic drugs in humans. We used this method to measure the effects of the menstrual cycle in normal women.
Methods: We tested 13 healthy women during the follicular (low-progesterone) and luteal (high-progesterone) phases of the menstrual cycle using paired TMS. The effect of a subthreshold conditioning pulse on the cortex was tested by measuring the response to a second suprathreshold test pulse and comparing it with the response elicited by the test pulse administered alone.
Results: Conditioning TMS produced more inhibition in the luteal phase than in the follicular phase (p = 0.01), of similar magnitude to the reported effect of benzodiazepine drugs.
Conclusions: This study provides the first direct evidence of changes in the excitability of a cortical network with the menstrual cycle. The results also show a potential confound for studies using transcranial magnetic stimulation in populations that include menstruating women.
- Received May 10, 1999.
- Accepted August 27, 1999.
AAN Members
We have changed the login procedure to improve access between AAN.com and the Neurology journals. If you are experiencing issues, please log out of AAN.com and clear history and cookies. (For instructions by browser, please click the instruction pages below). After clearing, choose preferred Journal and select login for AAN Members. You will be redirected to a login page where you can log in with your AAN ID number and password. When you are returned to the Journal, your name should appear at the top right of the page.
AAN Non-Member Subscribers
Purchase access
Letters: Rapid online correspondence
REQUIREMENTS
You must ensure that your Disclosures have been updated within the previous six months. Please go to our Submission Site to add or update your Disclosure information.
Your co-authors must send a completed Publishing Agreement Form to Neurology Staff (not necessary for the lead/corresponding author as the form below will suffice) before you upload your comment.
If you are responding to a comment that was written about an article you originally authored:
You (and co-authors) do not need to fill out forms or check disclosures as author forms are still valid
and apply to letter.
Submission specifications:
- Submissions must be < 200 words with < 5 references. Reference 1 must be the article on which you are commenting.
- Submissions should not have more than 5 authors. (Exception: original author replies can include all original authors of the article)
- Submit only on articles published within 6 months of issue date.
- Do not be redundant. Read any comments already posted on the article prior to submission.
- Submitted comments are subject to editing and editor review prior to posting.
You May Also be Interested in
Costs and Utilization of New-to-Market Neurologic Medications
Dr. Robert J. Fox and Dr. Mandy Leonard