Pinellia Total Alkaloids Modulate the GABAergic System in Hippocampal Formation on Pilocarpine-Induced Epileptic Rats

To investigate the neuromodulatory effect of pinellia total alkaloids (PTA) on the gamma-aminobutyric acidergic (GABAergic) system in epileptic rats, and preliminarily evaluate the anti-epileptic effect of PTA.

Ninety-one male Sprague-Dawley rats were randomized to a control group (n=17) or an epileptic group (n=74) using computer-generated random numbers. Status epilepticus (SE) was induced with pilocarpine in the epileptic group. Epileptic rats that survived SE were randomly divided into 4 groups, namely an epilepsy group (n=13), a topiramate (TPM, 60 mg/kg) group (n=12), a high-dose PTA (800 mg/kg) group (n=12), and a low-dose PTA (400 mg/kg) group (n=10). Treatments were given intragastrically once daily for 14 days. The control group and epilepsy group received normal saline. Spontaneous recurrent seizures (SRSs) were monitored 8-h daily for 7 days after treatment. Then, the hippocampal formation tissues were collected. GABA level was measured using enzyme-linked immunosorbent assay. Protein and mRNA expression levels of glutamate decarboxylase 65 (GAD65), GABA transporter-1 (GAT-1), GABA transaminase (GABA-T), and GABA_A receptor (GABA_AR) α4, α5, γ2 and δ subunits were measured using Western-blotting analysis and quantitative polymerase chain reaction.

PTA lowered the incidence and frequency of SRS (both doses vs. the TPM group, P>0.05). Compared with the epilepsy group, PTA increased the levels of GABA (both doses P<0.01) and GAD65 (mRNA, 800 mg/kg, P<0.01), and suppressed the levels of GAT-1 (mRNA, 800 mg/kg, P<0.01; 400 mg/kg, P<0.05), GABA-T (mRNA, both doses P<0.01), and GABA_AR δ subunit (protein, 800 mg/kg, P<0.05) and γ2 subunit (protein, both doses P<0.01). PTA upregulated the low-expressed mRNA levels of GABA_AR α5 subunit (400 mg/kg, P<0.01), δ subunit (800 mg/kg, P<0.05), and γ2 subunit (400 mg/kg, P<0.05).

PTA regulated the GABAergic system through modulating GABA levels and the expression levels of GAD65, GAT-1, GABA-T, and GABA_AR α4, α5, γ2 and δ subunits. PTA may exert anti-epileptic effects on the pilocarpine-induced epilepsy model.