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

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。

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

The effects of 17beta-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 17beta-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 17beta-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 17beta-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.