垂体腺苷酸环化酶激活肽减轻谷氨酸引起的大鼠海马神经元细胞内钙离子浓度升高的可能机理

目的　探讨垂体腺苷酸环化酶激活肽 38(PACAP 38)稳定海马神经元细胞内钙离子浓度(Ca2 + ]i)作用的可能机理。方法　取新生SD大鼠海马 ,用B2 7无血清培养基培养神经元 ;经Fura 2 /AM标记后 ,共聚焦显微镜下测定 Ca2 + ]i。结果PACAP 38(10pmol·L- 1)能抑制谷氨酸 (5 0 0 μmol·L- 1)所致海马神经元 Ca2 + ]i 升高 ,而Rp型硫化环腺苷酸 (2 0 μmol·L- 1)或氯化白屈菜赤碱 (0 .1μmol·L- 1)能阻断PACAP 38的抑制作用。二丁基环腺苷酸 (0 .1～ 10 0 μmol·L- 1)和豆寇酰佛波醇乙酯(0 .0 1～ 10 μmol·L- 1)也能抑制谷氨酸引起的海马神经元 Ca2 + ]i 升高。结论　PACAP 38减轻谷氨酸引起的海马神经元 Ca2 + ]i 升高可能与激活细胞内蛋白激酶A和蛋白激酶C信号转导系统有关

Underlying mechanism of pituitary adenylate cyclase activating polypeptide attenuating the increase in intracellular calcium concentration induced by glutamate in cultured hippocampal neurons of rats

AIM To investigate the possible mechanism of pituitary adenylate cyclase activating polypeptide-38 (PACAP-38) stabilizing calcium homeostasis in cultured hippocampal neurons. METHODS Hippocampus was isolated from newborn SD rats and dispersedly cultured in the B27 medium. Intracellular calcium concentration (［Ca²⁺］_i) was determined with the confocal microscope after hippocampal neurons were labeled by Fura2/AM. RESULTS ]PACAP-38（10 pmol·L^-1）inhibited the increase in ［Ca²⁺］_i induced by glutamate（500 μmol·L^-1） in cultured hippocampal neurons, and the inhibitory effect of PACAP- 38 was attenuated by adenosine 3′,5′-cyclic monophosphothioate, Rp- isomer (RpcAMPS, 20 μmol·L^-1) and chelerythrine chloride (0.1 μmol·L^-1). N⁶, 2′-O-Dibutyryladenosine 3′∶5′-cyclic monophosphate (dbcAMP, 0.1－100 μmol·L^-1) and phorbol 12-myristate 13-acetate (0.01－10 μmol·L^-1) reduced the increase in ［Ca²⁺］_i induced by glutamate. CONCLUSION ACAP-38 attenuates the increase in ［Ca²⁺］_i induced by glutamate in cultured hippocampal neurons, which may be mediated by protein kinase A and protein kinase C signal transduction system.