17β-雌二醇对大鼠脑片穹隆下器神经元放电活动的调变作用

Modulatory effects of 17β-estradiol on the electrical activity of subfornical organ neurons

用细胞外记录技术 ,在大鼠脑片穹隆下器 (subfornicalorgan ,SFO)上观察了 17β 雌二醇 (17β estradiol,E2 )对SFO神经元放电的影响 ,并进而分析其作用机制。实验结果如下 :(1) 15个SFO神经元在给予小剂量E2(0 1nmol/L)时 ,放电频率由 3 2 1± 0 37增至 6 79± 0 71Hz(P <0 0 0 1) ;而在给予大剂量E2 (10 0nmol/L)时 ,则放电频率由 3 44± 0 40Hz降至 1 44± 0 36Hz (P <0 0 1) ;(2 )在 7个SFO神经元应用谷氨酸NMDA受体阻断剂MK 80 1(5 0pmol/L) ,可阻断小剂量E2 (0 1nmol/L)对SFO神经元的兴奋效应 ;(3)在 7个SFO神经元应用NO生理性前体L 精氨酸 (L arginine ,1mmol/L)时 ,SFO神经元放电减少 ,且可阻断小剂量E2 (0 1nmol/L)对神经元的兴奋效应 ;(4 )在 6个SFO神经元应用NOS抑制剂L NG 硝基精氨酸甲酯 (L NAME ,10mmol)引起SFO神经元放电增加 ,并阻断大剂量E2 (10 0nmol/L)对SFO神经元的抑制效应。结果提示 :E2 对SFO神经元有双重作用。小剂量E2 使SFO神经元放电增加 ,这一效应可能与谷氨酸受体激活有关 ;而大剂量E2 则导致神经元放电减少 ,此效应可归因于NOS激活而引发NO生成。

The effects of 17β estradiol (E 2 ) on electrical activity of neurons in subfornical organ (SFO) slices were examined using extracelluar recording technique. The results are as follows. (1) In 15 SFO units, a low dose of E 2 (0 1 nmol/L) applied into superfusate induced an increase in discharge rate from 3 21±0 37 to 6 79±0 71 Hz ( P <0 001), whereas a high dose of E 2 (100 nmol/L ) caused a decrease in discharge rate from 3 44±0 40 to 1 44±0 36 Hz ( P <0 01); (2) glutamate NMDA receptor antagonist MK 801 (50 pmol/L) blocked the excitatory effects induced by low dose of 17β estradiol in 7 units; (3) L arginine (L arg, 1 mmol/L), a physiological precursor of NO, abolished the excitatory effects induced by low dose of 17β estradiol in 7 units; (4) application of N omega nitro L arginine methyl ester (L NAME, 10 mmol/L), an inhibitor of NOS, blocked the inhibitory effects induced by high dose of 17β estradiol in 6 units. The above results suggest that the estrogen exerts dual action on SFO neuron. E 2 at low dosage increases the discharge rate of SFO neuron, an effect which may be related to the activation of NMDA receptors, whereas E 2 at high dosage decreases the discharge rate, an effect which may be attributed to the activation of NOS with resultant production of NO.[WT5HZ]