Delta-opioid receptors on astroglial cells in primary culture: mobilization of intracellular free calcium via a pertussis sensitive G protein.

摘要: Astrocytes in primary culture from rat cerebral cortex were probed concerning the expression of delta-opioid receptors and their coupling to changes intracellular free calcium concentrations ([Ca2+]i). Fluo-3 or fura-2 based microspectrofluorometry was used for [Ca2+]i measurements on single astrocytes a mixed astroglial-neuronal culture. Application selective receptor agonist, [D-Pen2, D-Pen5]-enkephalin (DPDPE), at ranging 10 nM 100 microM, induced concentration-dependent increases (EC50 = 114 nM). The responses could be divided into two phases, with an initial spike followed by either oscillations sustained elevation [Ca2+]i. These effects blocked antagonist ICI 174864 (10 microM). astroglial cells further verified immunohistochemically, using specific antibodies, Western blot analyses. Pre-treatment pertussis toxin (100 ng/ml, 24 h) activation, consistent Gi- Go-mediated response. not observed low extracellular Ca2+ partly nifedipine (1 microM), indicating involvement L-type channels. Stimulating neurons DPDPE resulted decrease [Ca2+]i, which may closure plasma membrane channels these cells. current results suggest role response brain peptides that opioid part involve altered astrocytic homeostasis.