大戟二萜醇酯对大鼠颈上神经节胆碱能传递的影响

EFFECTS OF PHORBOL ESTERS ON CHOLINERGIC TRANSMISSION IN RAT SUPERIOR CERVICAL GANGLIA

应用细胞内生物电记录技术观察了两种大戟二萜醇酯对大鼠颈上神经节胆碱能传递的影响.灌流5或10μmol/L 的4β-大戟二萜醇-12,13-双丁酯(PDB)增大膜电阻而不影响膜电位,对刺激节前神经诱发的快兴奋性突触后电位(f-EPSP)及外源性乙酰胆碱(ACh)引起的 ACh电位均有浓度依赖性的增强作用,并诱导自发性 EPSP,表明 PDB 通过突触前、后机制易化交感神经节的胆碱能传递.4β-大戟二萜醇-12-肉豆蔻酯-13-乙酯(PMA,10μmol/L)灌流30min 对神经节细胞的电生理性质及其胆碱能传递无明显影响.

By intracellular recording techniques,the effects of two phorbol esters on cholinergic transmission were investigated in the rat superior cervical ganglion(SCG)prepara- tion.Superfusion of 4β-phorbol-12,13-dibutyrate(PDB,5 or 10/μmol/L)onto 16 cells for 10-20 min facilitated the fast excitatory postsynaptic potentials(f-EPSP)evoked by preganglionic nerve stimulation in a concentration-dependent manner.At 5μmol/L,PDB en- hanced f-EPSPs by 64±13%(n=6,P<0.05)in amplitude,24±15%(P<0.05)in duration, and increased the average amplitude of orthodromic spikes from 65 mV to 72 mV(n=3).At 10μmol/L,f-EPSPs were potentiated to become spikes in all 6 cells investigated.During bath with PDB(5μmol/L),input membrane resistance was increased by 15-57%(P<0.01)in 7 cells,without detectable change in membrane potential.In 8 of 16 tested cells,the rccording timebase became much thicker than control during superfusion of PDB,which resulted from the spontaneous EPSPs.In 5 cells,the potentiation of both f-EPSPs and exogenous ACh-induced potentials was found.During bath of 4β-phorbol-12-myristate-13-acetate(10/μmol/L)for 30 min,no significant changes in membrane properties and f-EPSPs were observed in 7 cells tested.The results indicate that phorbol ester PDB potentiates the cholinergic transmission in SCG neurons by both presynaptic and postsynaptic mechanism.