title: β-Adrenoceptor activation depresses brain inflammation and is neuroprotective in lipopolysaccharide-induced sensitization to oxygen-glucose deprivation in organotypic hippocampal slices.
abstract: BACKGROUND
  Inflammation acting in synergy with brain ischemia aggravates perinatal ischemic brain damage. The sensitizing effect of pro-inflammatory exposure prior to hypoxia is dependent on signaling by TNF-α through TNF receptor (TNFR) 1. Adrenoceptor (AR) activation is known to modulate the immune response and synaptic transmission. The possible protective effect of α and β AR activation against neuronal damage caused by tissue ischemia and inflammation, acting in concert, was evaluated in murine hippocampal organotypic slices treated with lipopolysaccharide (LPS) and subsequently subjected to oxygen-glucose deprivation (OGD).
  
  
  METHODS
  Hippocampal slices from mice were obtained at P6, and were grown in vitro for 9 days on nitrocellulose membranes. Slices were treated with β1(dobutamine)-, β2(terbutaline)-, α1(phenylephrine)- and α2(clonidine)-AR agonists (5 and 50 μM, respectively) during LPS (1 μg/mL, 24 h) -exposure followed by exposure to OGD (15 min) in a hypoxic chamber. Cell death in the slice CA1 region was assessed by propidium iodide staining of dead cells.
  
  
  RESULTS
  Exposure to LPS + OGD caused extensive cell death from 4 up to 48 h after reoxygenation. Co-incubation with β1-agonist (50 μM) during LPS exposure before OGD conferred complete protection from cell death (P < 0.001) whereas the β2-agonist (50 μM) was partially protective (p < 0.01). Phenylephrine was weakly protective while no protection was attained by clonidine. Exposure to both β1- and β2-agonist during LPS exposure decreased the levels of secreted TNF-α, IL-6 and monocyte chemoattractant protein-1 and prevented microglia activation in the slices. Dobutamine remained neuroprotective in slices exposed to pure OGD as well as in TNFR1-/- and TNFR2-/- slices exposed to LPS followed by OGD.
  
  
  CONCLUSIONS
  Our data demonstrate that activation of both β1- and β2-receptors is neuroprotective and may offer mechanistic insights valuable for development of neuro-protective strategies in neonates.
authors.affiliation: Pediatrics, Lund University, Lund, Sweden.
authors.forename: Tina
authors.initials: T
authors.lastname: Markus
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Hansson
authors.forename: Tobias
authors.initials: T
authors.lastname: Cronberg
authors.forename: Corrado
authors.initials: C
authors.lastname: Cilio
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Wieloch
authors.forename: David
authors.initials: D
authors.lastname: Ley
mesh_terms: D058646:Adrenergic alpha-1 Receptor Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death; D016207:Cytokines / Q000378:metabolism; D004280:Dobutamine / Q000494:pharmacology; D004660:Encephalitis / Q000378:metabolism* / Q000473:pathology; D005947:Glucose / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000235:genetics / Q000378:metabolism; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000235:genetics / Q000378:metabolism; D013726:Terbutaline / Q000494:pharmacology; D046509:Tissue Culture Techniques
chemical_list: D058646:Adrenergic alpha-1 Receptor Agonists; D000318:Adrenergic beta-Agonists; D016207:Cytokines; D008070:Lipopolysaccharides; D018696:Neuroprotective Agents; D011943:Receptors, Adrenergic, beta; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; C506236:Tnfrsf1a protein, mouse; D010656:Phenylephrine; D004280:Dobutamine; D005947:Glucose; D013726:Terbutaline; D010100:Oxygen