title: Bud extracts from Tilia tomentosa Moench inhibit hippocampal neuronal firing through GABAA and benzodiazepine receptors activation.
abstract: BACKGROUND
  Tilia tomentosa Moench bud extracts (TTBEs) is used in traditional medicine for centuries as sedative compound. Different plants belonging to the Tilia genus have shown their efficacy in the treatment of anxiety but still little is known about the mechanism of action of their bud extracts.
  
  
  OBJECTIVE
  To evaluate the action of TTBEs as anxiolytic and sedative compound on in vitro hippocampal neurons.
  
  
  METHODS
  The anxiolytic effect of TTBEs was assayed by testing the effects of these compounds on GABAA receptor-activated chloride current of hippocampal neurons by means of the patch-clamp technique and microelectrode-arrays (MEAs).
  
  
  RESULTS
  TTBEs acutely administered on mouse hippocampal neurons, activated a chloride current comparable to that measured in the presence of GABA (100 µM). Bicuculline (100 µM) and picrotoxin (100 µM) blocked about 90% of this current, while the remaining 10% was blocked by adding the benzodiazepine (BDZ) antagonist flumazenil (30 µM). Flumazenil alone blocked nearly 60% of the TTBEs activated current, suggesting that TTBEs binds to both GABAA and BDZ receptor sites. Application of high-doses of TTBEs on spontaneous active hippocampal neurons grown for 3 weeks on MEAs blocked the synchronous activity of these neurons. The effects were mimicked by GABA and prevented by picrotoxin (100µM) and flumazenil (30 µM). At minimal doses, TTBEs reduced the frequency of synchronized bursts and increased the cross-correlation index of synchronized neuronal firing.
  
  
  CONCLUSIONS
  Our data suggest that TTBEs mimics GABA and BDZ agonists by targeting hippocampal GABAergic synapses and inhibiting network excitability by increasing the strength of inhibitory synaptic outputs. Our results contribute toward the validation of TTBEs as effective sedative and anxiolytic compound.
authors.affiliation: Department of Drug Science and Technology, University of Torino, Corso Raffaello 30, 10125 Torino, Italy. Electronic address: arianna.allio@unito.it.
authors.forename: Arianna
authors.initials: A
authors.lastname: Allio
authors.affiliation: Department of Drug Science and Technology, University of Torino, Corso Raffaello 30, 10125 Torino, Italy. Electronic address: chiara.calorio@unito.it.
authors.forename: Chiara
authors.initials: C
authors.lastname: Calorio
authors.affiliation: Department of Drug Science and Technology, University of Torino, Corso Raffaello 30, 10125 Torino, Italy. Electronic address: claudio.franchino@unito.it.
authors.forename: Claudio
authors.initials: C
authors.lastname: Franchino
authors.affiliation: Department of Drug Science and Technology, University of Torino, Corso Raffaello 30, 10125 Torino, Italy. Electronic address: daniela.gavello@unito.it.
authors.forename: Daniela
authors.initials: D
authors.lastname: Gavello
authors.affiliation: Department of Drug Science and Technology, University of Torino, Corso Raffaello 30, 10125 Torino, Italy. Electronic address: emilio.carbone@unito.it.
authors.forename: Emilio
authors.initials: E
authors.lastname: Carbone
authors.affiliation: Department of Drug Science and Technology, University of Torino, Corso Raffaello 30, 10125 Torino, Italy. Electronic address: andrea.marcantoni@unito.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Marcantoni
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D001640:Bicuculline / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005442:Flumazenil / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010852:Picrotoxin / Q000494:pharmacology; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D011963:Receptors, GABA-A / Q000378:metabolism; D032384:Tilia / Q000737:chemistry*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
chemical_list: D014151:Anti-Anxiety Agents; D001640:Bicuculline; D005442:Flumazenil; D006993:Hypnotics and Sedatives; D010852:Picrotoxin; D010936:Plant Extracts; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid
keywords: Anxiolytic drug; Benzodiazepines; Buds; GABA(A) receptors; Microelectrode array (MEA); Tilia tomentosa Moench