Circulating Levels of Allopregnanolone, an Anticonvulsant Metabolite of Progesterone, in Women with Partial Epilepsy in the Postcritical Phase

Abstract

Summary Purpose: Several lines of evidence indicate that there exists a relation between ovarian hormones and epilepsy. Estrogens decrease seizure threshold and increase brain excitability, whereas progesterone has an inhibitory effect and reduces epileptiform activity. Recently considerable interest has turned to neuroactive steriods, a group of progesterone metabolites, as endogenous modulators of excitability of the central nervous system (CNS). Their ability to alter neuronal firing rapidly occurs through interaction with γ‐aminobutyric acid (GABA) A receptor complex. In a previous experience, serum allopregnanolone (3α‐OH‐5α‐pregnan‐20‐one) levels were measured in 15 women with partial epilepsy in the intercritical phase, and no significant differences were found between patients and control subjects. Methods: To find out if there are changes in serum allopregnanolone levels after epileptic seizure, blood samples were drawn immediately, 15 min, and 6 h after a seizure in seven fertile females with partial epilepsy. Results: The most interesting finding is that allopregnanolone increases in serum during the first 15 min after partial seizures (p <0.05) and decreases after 6 h. Conclusions: These data are consistent with a role for allopregnanolone in the control of neuronal excitability and seizures.