Allopregnanolone and Pregnanolone Are Reduced in the Hippocampus of Epileptic Rats, but Only Allopregnanolone Correlates with Seizure Frequency

Abstract

<b><i>Background:</i></b> Neurosteroids modulate epileptic activity by interacting with the γ-aminobutyric acid type A receptor, but their brain levels are still undetermined. <b><i>Objectives:</i></b> We aimed to establish neurosteroid levels in the neocortex and hippocampus by liquid chromatography/mass spectrometry in epileptic rats. <b><i>Methods:</i></b> Kainic acid-treated rats were continuously monitored up to 9 weeks to determine seizure frequency by video electrocorticography (<i>n</i> = 23) and compared to age-matched controls monitored in the same manner (<i>n</i> = 11). <b><i>Results:</i></b> Decreased allopregnanolone (–50%; <i>p</i> < 0.05, Mann-Whitney test) and pregnanolone levels (–64%; <i>p</i> < 0.01) were found in the hippocampus, whereas pregnenolone sulfate, pregnenolone, progesterone, and 5α-dihydroprogesterone were nonsignificantly reduced. No changes were found in the neocortex. Moreover, allopregnanolone (but not pregnanolone) levels were positively correlated with seizure frequency (<i>r</i><sup>2</sup> = 0.4606, <i>p</i> < 0.01). <b><i>Conclusion:</i></b> These findings indicate a selective reduction in hippocampal levels of 3α-reduced neurosteroids. This reduction was partially mitigated by seizures in the case of allopregnanolone.

Topics & Concepts