de Barioglio S R, Brito M I
Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Peptides. 1996;17(8):1303-6. doi: 10.1016/s0196-9781(96)00229-x.
This study was carried out to investigate possible interactions between some glutamatergic agonists and the peptide alpha-MSH upon the cyclic AMP levels. We used an in vitro tissue slice preparation incubated in the presence of different glutamatergic agonists such as N-methyl-D-aspartic acid (NMDA), quisqualic acid (QUIS), kainic acid (KA), and the peptide alpha-MSH together with each agonist. Slices containing caudate putamen and accumbens were chosen according to neurochemical data indicating that the striatum contains a moderate amount of MSH binding sites and also receives glutamatergic innervation. Exposure of these slices to either MSH or to the agonists NMDA or QUIS resulted in an increase in the cAMP levels in relation to controls. Nevertheless, incubation with KA resulted in no changes in the nucleotide levels. The combination of MSH/NMDA induced a reduction of cAMP levels in relation to those obtained with NMDA alone. The combinations of QUIS/MSH or KA/MSH also induced variations in the values of nucleotide in relation to the those obtained with the peptide alone or with the corresponding agonist; these changes were related to the dose of agonist used in each case. The results obtained in these experiments suggest the existence of some interaction between the peptide and the agonist used.
本研究旨在探讨某些谷氨酸能激动剂与肽α-促黑素（α-MSH）对环磷酸腺苷（cAMP）水平可能存在的相互作用。我们使用了一种体外组织切片制备方法，将其置于不同的谷氨酸能激动剂如N-甲基-D-天冬氨酸（NMDA）、喹啉酸（QUIS）、 kainic酸（KA）以及与每种激动剂共同作用的肽α-MSH存在的环境中进行孵育。根据神经化学数据选择含有尾状壳核和伏隔核的切片，这些数据表明纹状体含有适量的MSH结合位点，并且还接受谷氨酸能神经支配。将这些切片暴露于MSH、激动剂NMDA或QUIS中，与对照组相比，cAMP水平均有所升高。然而，与KA孵育后，核苷酸水平没有变化。与单独使用NMDA相比，MSH/NMDA组合导致cAMP水平降低。QUIS/MSH或KA/MSH组合相对于单独使用肽或相应激动剂时，也引起了核苷酸值的变化；这些变化与每种情况下使用的激动剂剂量有关。在这些实验中获得的结果表明，所使用的肽和激动剂之间存在某种相互作用。
