关键词: 褪黑激素, 血压, 昼夜节律

Abstract: 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.

Key words: melatonin, blood pressure, circadian rhythms