title: Leptin induces nitric oxide synthase type II in C6 glioma cells. Role for nuclear factor-kappaB in hormone effect.
abstract: Astrocytes in the CNS produce inflammatory mediators in response to several stimuli and cytokines. Here we investigated the in vitro effect of leptin on inducible nitric oxide synthase (iNOS) expression in a glioma cell line (C6). After hormone stimulation, culture media were analysed for accumulated stable oxidation products of NO (NO2(-) and NO3(-), designated as NO(x)), cellular RNA was extracted to determine iNOS mRNA level by RT-PCR and cellular lysates were prepared for protein expression. Leptin induced a concentration-dependent increase of NO release, related to iNOS induction. This effect was potentiated by IFN-gamma, or TNF-alpha, or IFN-gamma plus IL-1beta. Pyrrolidine dithiocarbamate (PDTC) and N-alpha-tosyl-L-lysine chloromethyl ketone (TLCK), two inhibitors of NF-kappaB activation, as well as the specific proteasome inhibitor MG132, blocked leptin-induced iNOS. The role of NF-kappaB was also confirmed by time course studies on degradation of IkappaB-alpha, which began to degrade 5 min after treatment with leptin and returned to basal level after 30-60 min. Pre-incubation of cells with MG132 inhibited leptin-induced IkappaB-alpha degradation. These results confirm the pro-inflammatory role of leptin and identify it as a potential up-regulator of cytokine-induced inflammatory response in the CNS.
authors.affiliation: Department of Experimental Pharmacology, University of Naples, Federico II, via D. Montesano, 49-80131 Naples, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Mattace Raso
authors.forename: Emanuela
authors.initials: E
authors.lastname: Esposito
authors.forename: Anna
authors.initials: A
authors.lastname: Iacono
authors.forename: Maria
authors.initials: M
authors.lastname: Pacilio
authors.forename: Anna
authors.initials: A
authors.lastname: Coppola
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bianco
authors.forename: Sabrina
authors.initials: S
authors.lastname: Diano
authors.forename: Raffaele
authors.initials: R
authors.lastname: Di Carlo
authors.forename: Rosaria
authors.initials: R
authors.lastname: Meli
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005910:Glioma / Q000378:metabolism*; D020738:Leptin / Q000008:administration & dosage / Q000378:metabolism*; D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D051381:Rats
chemical_list: D016207:Cytokines; D020738:Leptin; D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II