催产素对大鼠背根神经节分离细胞
GABA激活电流的调制作用
谭振军 魏劲波 李之望 邵梅 胡祁生 彭碧文
摘 要: 在急性分离的大鼠背根神经节(dorsal root ganglion, DRG)细胞上, 应用全细胞膜片箝技术观察了预加催产素(oxytocin,
OT)对GABA激活电流的调制作用。结果如下: (1) 大多数细胞(48/52, 90.5%)对GABA敏感。(2) OT可引起51.3% (20/39)的受检细胞出现外向膜电流;
43.6% (17/39)无明显膜反应; 5.1%(2/39)出现内向膜电流。(3)预加OT (10－12～10－9
mol/L)30～90 s后, 大部分GABA激活电流增加(33/39, 84.6%); 少数无明显反应(4/39, 10.3%)或略有抑制(2/39,
5.1%)。GABA (10－4 mol/L)增强作用为浓度依赖性的, 在OT浓度为10－12、 10－11、
10－10、 10－9 mol/L时, GABA激活电流的增强分别为: 24.1±7.6%(n=6),
33.4±6.9% (n=9), 40.2±6.5% (n=13), 67.2±14.8%(n=5)。 当OT浓度升高(10－8及10－7
mol/L)时, GABA激活电流不但不增高, 反而被抑制。(4) 预加OT后, GABA激活电流量-效曲线的Kd值降低, 最大反应浓度增加。 (5) 预加OT和未预加OT的电流-电压曲线显示,
其翻转电位均在0 mV左右。以上结果提示: OT受体激活后可能通过相应的胞内转导机制增强GABA激活电流, 从而在初级感觉神经元水平加强GABA的突触前抑制作用而减弱感觉信息的传递。
关键词: 催产素; 背根神经节; GABAA受体; 全细胞膜片箝; 调制
学科分类号: Q424
Modulation of
GABA-activated currents by oxytocin in rat
dorsal root ganglion neurons
TAN
Zhen-Jun, WEI Jin-Bo,
HU Qi-Sheng, PENG Bi-Wen
（Department of Physiology, Hubei Medical University, Wuhan
430071;）
LI Zhi-Wang SHAO Mei
（Research Center of Experimental Medicine, Tongji Medical
University, Wuhan 430030）
Abstract:
Experiments were performed on freshly
isolated dorsal root ganglion (DRG) neurons of rat. GABAA-activated
currents were recorded using the whole-cell patch clamp technique. The majority
of the neurons (48/52, 90.5%) were sensitive to GABA (10－6～10－3
mol/L). Application of oxytocin (OT) induced outward membrane responses in
51.3% (20/39) of the neurons, no apparent responses in 43.6% (17/39) and inward
responses in 5.1% (2/39). 10－12, 10－11, 10－10
and 10－9 mol/L OT increased 10－4 mol/L GABA-activated
currents to 24.1±7.6%(n=6), 33.4±6.9%(n=9), 40.2±6.5%(n=13) and
67.2±14.8%(n=5), respectively. After preapplication of OT, the Kd value for
GABAA-activated currents decreased, while the response obtained at
the maximum concentration increased. The results suggest that the enhancement
of GABA-activated currents by OT may suppress primary sensory transmission by
potentiating pre-synaptic inhibition of GABA.
Key words: oxytocin; dorsal root ganglion;
GABAA receptor; whole-cell patch clamp; modulation
Corresponding author. Tel: 027-87330596; Fax: 027-87307966;
E-mail: wei.jingbo@163.net
谭振军（湖北医科大学生理教研室, 武汉 430071）
魏劲波（湖北医科大学生理教研室, 武汉 430071）
李之望（同济医科大学实验医学研究中心， 武汉 430030）
邵梅（同济医科大学实验医学研究中心， 武汉 430030）
胡祁生（湖北医科大学生理教研室, 武汉 430071）
彭碧文（湖北医科大学生理教研室, 武汉 430071）
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Received 1999-12-27 Accepted 2000-06-03