Second generation anti-epileptic drugs adversely affect reproductive functions in young non-epileptic female rats

Reproductive endocrine disturbances are a major health concern in women with epilepsy due to their long term use of antiepileptic drugs (AEDs). Second generation AEDs such as topiramate (TPM) and gabapentin are frequently used for the treatment of epilepsy as well as migraine, bipolar disorder etc. Despite the widespread clinical complications, however the definitive mechanism(s) mediating the side effects of TPM and gabapentin remain obscure. The present study was aimed to evaluate the long term effects of TPM and gabapentin on reproductive functions in young female Wistar rats. Estrous cyclicity, ovarian histology as well as estradiol, LH, leptin and insulin hormones level were studied to elucidate the long-term effect of these AEDs monotherapy on reproductive functions in non-epileptic animals. Further to explore the effects on gonadotropin releasing hormone (GnRH) neuroendocrine plasticity, the expression of GnRH, gamma-amino butyric acid (GABA), glutamic acid decarboxylase (GAD), glial fibrilliary acidic protein (GFAP) and polysialylated form of neural cell adhesion molecule (PSA-NCAM) was studied in median eminence (ME) region of these animals by immunohistochemistry, Western blot hybridization and RT-PCR. Our results demonstrate that TPM and gabapentin treatment for 8 weeks cause reproductive dysfunction as ascertained by disturbed hormonal levels and estrous cyclicity as well as alterations in GABAergic system and GnRH neuronal-glial plasticity. Our findings suggest that treatment with TPM and gabapentin disrupts the complete hypothalamo-hypophyseal-gonadal axis (HPG) through GnRH pulse generator in hypothalamus.