α1-Adrenergic Receptor Coupling with Phospholipase-C Is Negatively Regulated by Protein Kinase-C in Primary Cultures of Hypothalamic Neurons and Glial Cells*

In the present work we evaluated the interactions of adrenergic receptors with phospholipase-C (PLC) and protein kinase-C (PKC), using an in vitro system of hypothalamic neurons and astroglial cells in primary cultures. The study was performed on immature neurons after 7 days in vitro (7 Div), that is before synaptogenesis, as well as on mature cells (14 Div). Comparisons were made between neurons and glial cells at the corresponding developmental stages. Norepinephrine (NE) increased inositol phosphates (IPs) formation in a doseand time-dependent manner. The NE effect was mediated by α-receptor (αlR) and was observed in young cells before synaptogenesis as well as in mature neuronal cultures; its amplitude was enhanced during the latter stage of the neuronal development. The coupling of αlR with PLC was partially sensitive to pertussis toxin treatment and did not implicate the activationof calcium voltage-dependent channels. Activation of PKC by 12-O-Tetradecanoylphorbol 13-acetate (TPA) inhibited in a t...