Inter-ictal and post-ictal circulating levels of allopregnanolone, an anticonvulsant metabolite of progesterone, in epileptic children

Allopregnanolone belongs to a group of neuroactive steroid hormones, or neurosteroids, synthesized and acting within the brain and is as a potent endogenous positive modulator of GABAA receptor complex. Administration of allopregnanolone protects rats against pentylentetrazol, bicuculline, kainic acid, and picrotoxin-induced seizures. We investigated serum allopregnanolone levels in children with active epilepsy at pubertal Tanner's stage I (n=52). Blood specimens were collected at least 12h after a seizure (inter-ictal). In a subgroup of patients (n=11), specimens were also collected within 30min from a seizure attack (post-ictal). Healthy age-matched children (n=18) served as controls. Serum allopregnanolone was measured by radioimmunoassay using a polyclonal antiserum. The inter-ictal serum allopregnanolone levels in the epileptic children were not statistically different from those detected in the control group, whereas post-ictal levels were significantly higher than the inter-ictal ones (P=0.0001). In this subgroup of patients allopregnanolone levels decreased to the basal values during the following 12h. Serum allopregnanolone levels may therefore reflect changes in neuronal excitability, and allopregnanolone appears to be a reliable circulating marker of epileptic seizures. It is possible that increased post-ictal serum levels of allopregnanolone may play a role in modulating neuronal excitability and may represent an endogenous mechanism of seizure control. © 2003 Elsevier Science B.V. All rights reserved.