The effects of tamoxifen and soy on dark neuron production in hippocampal formation after pentylenetetrazole-induced repeated seizures in rats

Abstract

BackgroundRegarding the similar modulatory effects of both soy and tamoxifen on the actions of estrogen which have previously reported, the aim of the present study was to investigate the effects of these two estrogen like compounds alone and in combination on dark neuron production in hippocampal formation of ovariectomized rats after pentylenetetrazole-induced repeated seizure. MethodsThe rats were randomly divided into six groups: control, sham, OVX, OVX-soy (OVX-S), OVX-tamoxifen (OVX-T) and OVX-soy-tamoxifen (OVX-S-T). The animals of OVX-S, OVX-T and OVX-S-T groups received the soy extract (60mg/kg; i.p.), tamoxifen (10mg/kg) or both for 2 weeks before induction of seizures. The animals of these groups were also treated by soy extract, tamoxifen or both before each injection of PTZ (40mg/kg) for 6 days. The animals of sham and OVX groups received saline plus tween instead of tamoxifen and soy extract. The animals of control group did not treat by PTZ, tamoxifen and soy. The rats were placed in Plexiglas cages separately and observed for 60min. The brain tissues were then removed and subjected for histological studies. ResultsA significant decrease in the seizure score was seen in OVX group comparing to sham. The animals of both OVX-T and OVX-S groups had a significant higher seizure score compared to OVX group. Co-treatment of the ovariectomized rats by both soy extract and tamoxifen decreased the seizure score compared to OVX-S and OVX-T groups. The results of histological study showed that the dark neuron number in CA1, CA2, CA3 and dentate gyrus (DG) of hippocampus area in OVX-T and OVX-S groups was higher than that of OVX group (P<0.05–P<0.01). In CA3, the produced dark neurons of OVX-S-T group were lower than that OVX-S group (P<0.01). ConclusionThe results of present study showed that treatment of the ovariectomized rats by either soy extract or tamoxifen increased the seizure score as well as dark neurons. Co-treatment with soy extract and tamoxifen did not potentiate the effects of each of them alone. Co-administration of the tamoxifen and soy extract inhibited the effects of the soy extract and tamoxifen when they administered alone.