An in vitro Study on the Contractility of Epileptic Myometrium and Effects of Antiepileptic Agents on Oxytocin-Induced Contractions of Myometrium Isolated from Absence Epileptic WAG/Rij Rats.

BACKGROUND/AIMS: The aim of this study was to determine whether spontaneous and stimulated contractile activity of myometrium in epileptic rats is different from healthy ones, and whether antiepileptic drugs (AEDs) have any direct influence on myometrial contractility.

METHODS

Myometrial strips from nonpregnant and pregnant adult epileptic WAG/Rij and Wistar rats were suspended in organ bath containing physiological salt solution (37°C and pH 7.4, aerated with 95% oxygen-5% CO2), and isometric contractions were recorded. Effects of cumulative concentrations of selected AEDs including phenytoin, levetiracetam, and valproic acid alone and in combination on oxytocin-induced contractions was examined. Contractile parameters assessed included the area under curve, amplitude, and frequency of contractions, evaluated by 10-min periods. Data were analyzed using one-way analysis of variance and Tukey HSD test.

RESULTS

Spontaneous myometrial contractility and responses to oxytocin showed species difference. Compared with that of control Wistar rats, spontaneous contractions of myometrium from nonpregnant epileptic WAG/Rij rats were significantly higher while being significantly lower in pregnant preparations. Upon stimulation with oxytocin, WAG/Rij myometrium showed significantly lower contractile response compared with preparations from healthy control Wistars (p < 0.01). Phenytoin and valproate caused concentration-dependent significant attenuation (p < 0.05) of spontaneous and oxytocin-induced contractions of myometrium from WAG/Rij and Wistar rats, both nonpregnant and pregnant.

CONCLUSION

Myometrial smooth muscle from epileptic rats showed different spontaneous and oxytocin-induced contractility, and AEDs showed contractile modulatory actions, phenytoin being the most and levetiracetam the least effective. Although in vitro, our findings may be of clinical implications with regard to obstetric complications in epileptics and use of AEDs during pregnancy, and warrants further investigations.