Rat Hippocampal Dopamine Neurotransmitter Activity Class P300

Objective: To evaluate the role of hippocampal dopamine activities in the production of P300-like potentials and elucidate its mechanism. Methods: (l)The electrodes ith stainless steel guide cannulae were implanted into the ventral or dorsal hippocampi of rats by means of stereotaxic technique.(2)Changes of hippocampal P300-like potentials were observed, induced by local infusion of D2 agonist quinpirole and antagonist sulpiride into the ventral hippocampi, dorsal hippocampi and lateral ventricles respectively.(3)Changes of hippocampal P300-like potentials were observed after lesions of the meso-hippocampal dopaminergic systems. (4) The extracellular DA and DQPAC were collected by the push-pull method in the ventral and dorsal hippocampi and their contents were measured by hkh- performance liquid chromatography with electrochemical detection(IIPLC- EC).(5)The lesions of the dopaminergic cells in the substantia nigra and ventral tegmental area after injection of 6-QHDA were observed by anti-tyrosine hydroxylase(TH) immunohistochemical staining. Result: (1) The peak latencies of ventral hippocampal P300-like potentials were significantly prolonged one half an hour after infusing sulpiride into ventral hippocampi and recovered two hours later. The peak latencies of ventral hippocampal P300-like potentials were shortened one half an hour after infusing quinpirole into ventral hippocampi and recovered two hours later. The polarities of P300-like potentials had no changes. (2) The peak latencies of dorsal hippocampal P300-like potentials had no changes after infusing sulpiride or quinpirole into the dorsal hippocampi. (3) The contents of dopamine in ventral hippocampi were higher than those in dorsal hippocampi in the normal animals. (4) The contents of dopamine decreased and the peak latencies of P300-like potentials increased in the ventral hippocampi after lesions of the meso-hippocampal dopaminergic systems. Conclusion: (1) Hippocampus is the important one of the generators of P300-like potential. (2) There exist meso-hippocampal dopaminergic systems in rats. (3) Hippocampal neurons innervated by the dopamineralc terminals mainly locate in the ventral hippocampal aera in rats. (4) The dopaminer2ic activities in the ventral hippocampi, but not the dorsal hippocampi, play an important role in the production of P300-like potentials. (5) The activities of meso-hippocampal dopaminergic projection take part in the generation of the hippocampal P300-like potentials in rats.