Rapid down regulation of pyroglutamyl peptidase II activity by arachidonic acid in primary cultures of adenohypophyseal cells

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• 作者：Baeza ; Martin A. ; Ponce ; Georgina ; Joseph-Bravo ; Patricia ; Charli ; Jean-Louis
• 关键词：TRH ; Peptide degradation ; Pyroglutamyl aminopeptidase II ; Adenohypophysis ; Arachidonic acid ; Lipoxygenase ; Prolactin ; Ectopeptidase
• 刊名：Life Sciences
• 出版年：2001
• 出版时间：March 16, 2001
• 年：2001
• 卷：68
• 期：17
• 页码：2051-2060
• 全文大小：177 K

文摘

Thyrotropin releasing hormone (TRH; pglu-his-proNH2) is inactivated, in the extracellular space, by pyroglutamyl aminopeptidase II (PPII), a narrow specificity ectopeptidase. In adenohypophysis, multiple hormones regulate PPII surface activity. The intracellular pathways of regulation are still poorly understood. Since some of the neurohormones which regulate PPII activity, including TRH and dopamine, transduce in part their effect through modulation of arachidonic acid (AA) mobilization, we have tested its role in regulation of PPII activity in primary cultures of rat adenohypophyseal cells. Melittin concentrations from 0.25 to 1 ug/ml induced a rapid decrease of PPII activity; 0.5 ug/ml caused a maximum effect (38–45 % inhibition) at 20–30 min. AA (0.5 or 5 uM) also inhibited PPII activity (42–72 % , maximum at 20 min); AA effect was reversible, with values approaching control at 1 h. The inhibitory effect of AA was blocked by lipoxygenase (10 uM nordihidroguaiaretic acid) but not ciclooxygenase inhibitors (10 uM indomethacin) suggesting the involvement of the lipoxygenase pathway. These data show that production of arachidonic acid by adenohypophyseal cells can rapidly but transiently down regulate surface PPII activity. This is the first evidence that AA mobilization can regulate the activity of an ectopeptidase.