神经降压素对大鼠脊髓背角胶状质内突触前神经递质释放的影响

The effects of neurotensin on the presynaptic neurotransmitter release in substantia gelatinosa of the spinal cord in the rat

目的:研究内源性神经肽神经降压素(neurotensin,NT)在脊髓背角胶状质(substantia gelatinosa,SG)内对突触前神经递质释放的影响。方法:采用全细胞电压膜片钳记录方法,在脊髓薄片上观察NT对SG内微小兴奋性突触后电流(mEPSCs)和微小抑制性突触后电流(mIPSCs)的频率和幅值的影响。结果:(1)灌流NT(2μmol/L)对SG内神经元mEPSCs的频率和幅值均无明显影响,说明NT不影响SG内兴奋性神经递质的释放;(2)灌流NT(2μmol/L)能增加SG内神经元mIPSCs的频率,但对幅值无明显影响,即NT可引起突触前抑制性神经递质的释放增加,但对突触后神经元无明显影响。结论:NT可通过增加SG内抑制性神经递质释放的途径抑制伤害性信息的传递,从而实现镇痛效应。

Objective： To investigate the effects of neurotensin （NT）, an endogenous neuropeptide, on presynaptic neurotransmitter release within substantia gelatinosa （ SG ） of the spinal cord. Methods： By using whole-cell voltage- patch clamp recording method, the effects of NT on the frequency as well as amplitude of miniature excitatory postsynaptic currents （mEPSCs） and miniature inhibitory postsynaptic currents （mIPSCs） of SG neurons in the spinal cord slice were studied, respectively. Results： （1） In the presence of NT （2 μmol/L） the frequency and amplitude of mEPSCs of SG neurons did not show remarkable changes, indicating that NT has no effect on the excitatory neurotransmitter release in SG; （2） NT （2 μmol/L） significantly potentiated the frequency rather than amplitude of mlPSCs in SG, illustrating that NT may enhance the presynaptic release of inhibitory neurotransmitters and might not have effect on postsynaptic neurons in SG. Conclusions： NT may inhibit the nociceptive information transmission in SG via increasing the inhibitory neuro- transmitter release. Thus, it may play an analgesic role through this way in the spinal cord.