Contribution of estradiol in sex-dependent differences of pentylenetetrazole-induced seizures in rats

In the present study the contribution of estradiol in sex-dependent differences of pentylenetetrazole (PTZ)-induced seizures was investigated in rats. The rats were divided into four groups: 1) sham, 2) ovariectomized (OVX), 3) ovariectomized-estradiol (OVX-Est) and 4) male. The OVX-Est group received estradiol valerate (2 mg/kg; i.m/4 weeks) while, male, sham and OVX groups received vehicle. The animals were injected by PTZ (90 mg/kg). The latencies to minimal clonic seizures (MCS) and generalized tonic-clonic seizures (GTCS), were recorded. Serum 17β-estradiol and testosterone levels were also determined using an Elisa kit. GTCS latency in OVX rats was higher than in sham-operated animals (P < 0.05). MCS and GTCS latency in the male group was significantly higher than in the sham, OVX and OVX-Est groups (P < 0.001 and P < 0.01). There was no significant difference in MCS or GTCS latencies among OVX-Est, sham and OVX groups. Serum 17β-estradiol level in the OVX group was significantly lower than in the sham (P < 0.01) and in the OVX-Est group it was higher than in the sham, OVX and male groups (P < 0.01 and P < 0.001). Serum testosterone level in the male group was significantly higher than in all the other three groups (P < 0.001). It seems that testosterone probably has a more efficient role than estradiol in the gender dependent difference in seizure caused by PTZ in rats.