外侧缰核参与褪黑素的中枢降压作用

目的：研究外侧缰核（LHb）是否参与到褪黑素（MEL）中枢降压的过程中。方法:用玻璃微电极记录LHb神经元自发放电，利用静脉快速注射去甲肾上腺素引起动脉血压快速短暂升高和LHb自发放电频率的改变，来鉴别心血管兴奋性神经元和心血管抑制性神经元。并采用分别腹腔注射2 mg•kg^-1及LHb核团内微量注射4 mg•kg^-1MEL的方法，观察MEL对大鼠LHb心血管神经元自发放电和动脉血压的影响。结果：腹腔注射2 mg•kg^-1MEL影响大鼠LHb心血管神经元自发放电，MEL可以减少心血管兴奋性神经元的放电频率(平均减少38.40%±6.48%)，增加心血管抑制性神经元的放电频率(平均增加56.30%±8.45%）。LHb核团微量注射4 mg•kg^-1 MEL，引起动脉血压的下降（1.57 kPa±0.35 kPa）。 结论：MEL作用于LHb并引起动脉血压降低，LHb作为其靶点参与MEL的中枢降压作用。

Lateral habenular nucleus involved in central decrease of blood pressure induced by melatonin

Objective To study whether lateral habenular nucleus (LHb) was involved in the central decrease of blood pressure induced by melatonin (MEL). Methods The neuron spontaneous firings were recorded by a single-barrel glass electrode and the excitatory or inhibitory cardiovascular neurons were identified by recording the changes of neuron firing sequences induced by intravenous injection with noradrenaline. After rats were administrated with MEL or physiological saline (ip or microinjection into LHb), the firings of cardiovascular neurons and artery blood pressure were recorded. Results The administration of MEL (2 mg·kg~ -1, ip) could significantly vary the spontaneous firing sequences of cardiovascular neurons, leading to the decrease of excitatory neurons (38.40%±6.48%) and the increase of inhibitory neurons (56.30%±8.45%), compared with physiological saline control. The microinjection of MEL (4 mg·kg~ -1) into LHb also induced the decrease of artery blood pressure (1.57 kPa±0.35 kPa). Conclusion MEL could act on LHb and result in the decrease of artery blood pressure. So LHb could be the central site involved in the decrease of blood pressure induced by MEL.