The Effects of Acute Phenobarbital Application on the Different Phases of Long-term Potentiation in Rat Hippocampal CA1 Area

Abstract: To explore the effect of phenobarbital on the different phases of long-term potentiation at the therapeutic concentration in rat hippocampal CA1 area and its possible mechanisms， hippocampal slices prepared from male Wistar rats on postnatal 15 days were divided into three groups: PB pre-treatment group， PB earlytreatment group and PB late-treatment group. The effects of PB on field excitatory postsynaptic potentials (fEPSPs) after high-frequency stimulation (HFS) or double-pulse stimulation were examined with patch clamp technique. The expression of calmodulin-dependent protein kinase II (CaMK II) and phosphorylated CaMK II (p-CaMK II) were examined by Western blot analysis. We found that: (1) PB inhibited fEPSPs without modifying paired-pulse facilitation (PPF) which solely occured presynaptically as a simple form of synaptic plasticity; (2) pretreatment with PB before HFS decreased the fEPSPs slope; (3) no significant effects of PB on fEPSPs slope were found in two maintenance phases of LTP; (4) expression of p-CaMK II but not CaMK II decreased in PB pre-treatment group， and however no differences were detected of p-CaMK II and CaMK II expression in PB early-treatment group and PB late-treatment group. The results indicated that PB inhibited the induction of LTP postsynaptically through inhibiting the expression of p-CaMK II without modifying presynaptic neurotransmitter release and PB had no significant influence on the two maintenance phases of LTP with no effects on the expression of CaMK II and p- CaMK II.

CSTR: 32200.14.cjcb.2010.03.0013