Inhibitive Effect of N-nitro-L-arginine
on Hippocampal Neurons Excitation
CHEN Xiao-Chun, SHENG Chao, ZHENG Xiao-Xiang*
( Zhejiang Provincial Key Laboratory of Chinese Medicine Screening &
Appraise for Cardiocerebral Vascular & Nervous System, Department of
Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
)
Abstract The
inhibitive effect of N-nitro-L-arginine (L-NNA, a nitric oxide
synthase inhibitor) on the excitation of cultured rat hippocampal CA1 neurons,
stimulated by penicillin G(PG), was investigated. A rapid intracellular NO
production induced by PG (4 000 IU/ml) was disclosed when monitored with laser
scanningconfocal microscopy (LSCM). Pretreatment of L-NNA (0–10 μmol/L)
dose-dependently inhibited the NO production, and the intercellular level of
glutamate (15 min after PG stimulation) as well. Meanwhile, L-NNA(1 and 10
μmol/L) also significantly inhibited the immunoreactive methionine enkephalin
(ir-M-ENK) level. Furthermore, the immunoreactive dynorphin B (ir-DYN-B) level
was increased significantly by L-NNA (10 μmol/L). Finally, β-FNA (100 μmol/L,
an M-ENK receptor inhibitor) facilitated the inhibitive effect of L-NNA on the
Glu level, while nor-BIN (100 μmol/L, a DYN receptor inhibitor) suppressed that
effect. In conclusion,L-NNA could inhibit NO production induced by PG (4 000
IU/ml) stimulation, thuslowering the M-ENK level and increasing the DYN-B
level, and resulted in a down-regulation of the Glu level and the neuron
excitation.
Key words nitric oxide； glutamate； enkephalin； dynorphin； hippocampal neuron
*Corresponding author： Tel, 86-571-7951091； Fax, 86-571-7951676； e-mail, [email protected]