Central Effects of Phoenixin and Muscimol on Pentylenetetrazol-Induced Seizures during Various Stages of the Estrous Cycle among Rats

Catamenial epilepsy is a special form of epilepsy in women whom seizure aggravation is arranged with menstrual cycle that may affect up to 70 % of epileptic women. According to earlier studies, the role of neuropeptide Phoenixin (PNX) in the reproductive system has been observed and its antiepileptic effects have been proven. It also appears that the GABAergic system plays an important role in inhibition of seizures. Therefore, the aim of this study was to investigate the central effects of PNX and muscimol (GABA-A receptor agonist) on Pentylenetetrazol (PNT)-induced seizures during various stages of the estrous cycle among rats.

In this study, 120 adult female rats were randomly divided into five groups, including intracerebroventricular (ICV) injection of normal saline, PNX (5 μg), PNX (10 μg), muscimol (0.1 μg)+ PNX (5 μg) and muscimol (0.1 μg)+ PNX (10 μg), in proestrus, estrus, metestrus, and diestrus. After ICV injections, acute epilepsy was induced by intraperitoneal (IP) injection of 80 mg/kg of pentylentetrazole. Initiation time of myoclonic seizures (ITMS) and initiation time of tonic–clonic seizures (ITTS) were monitored and recorded for 30 min.

The results of the present study showed that PNX alone increased both ITMS and ITTS in all phases of estrus (p<0.05). Furthermore, the injection of PNX with muscimol significantly reinforced the effects of the PNX on ITMS and ITTS in all estrus stages (p<0.05).

The results showed that the antiepileptic activity of PNX was probably mediated by GABA-A receptors.