title: Synthesis and pharmacological properties of new GABA uptake inhibitors.
abstract: BACKGROUND
  γ-Aminobutanoic acid (GABA) is the principal inhibitory neurotransmitter in the mammalian central nervous system. The identification and subsequent development of the GABA transport inhibitors which enhance the GABA-ergic transmission has shown the important role that GABA transporters play in the control of numerous functions of the nervous system. Compounds which inhibit GABA uptake are used as antiepileptic drugs (tiagabine - a selective GAT1 inhibitor), they are also being investigated for other indications, including treatment of psychosis, general anxiety, sleep disorders, drug addiction or acute and chronic pain.
  
  
  METHODS
  In this paper, the synthesis of 2-substituted-4-(1,3-dioxoisoindolin-2-ylo)-butanamides and 2-substituted-4-aminobutanoic acids derivatives is described. These compounds were tested in vitro for their ability to inhibit GABA uptake. The inhibitory potency towards murine plasma membrane GABA transporters (mGAT1-4) was performed as [(3)H]GABA uptake assay based on stably transfected HEK cells. Compound 18, which demonstrated the highest affinity for mGAT1-4 (pIC(50) ranged from 4.42 for mGAT1 to 5.07 for mGAT3), was additionally investigated in several behavioral tests in mice.
  
  
  RESULTS
  Compound 18 increased the locomotor activity (14-38%) and had anxiolytic-like properties in the four-plate test (ED(50) = 9.3 mg/kg). It did not show analgesic activity in acute pain model, namely the hot plate test, however, it was antinociceptive in the acetic acid-induced writhing test (ED(50) = 15.3 mg/kg) and in the formalin model of tonic pain. In the latter assay, it diminished nocifensive behavior in both phases and in the first (neurogenic) phase of this test the obtained ED(50) value (5.3 mg/kg) was similar to morphine (3.0 mg/kg).
  
  
  CONCLUSIONS
  Compound 18 exhibited significant anxiolytic-like properties and was antinociceptive in some models of pain in mice. Moreover, it did not impair animals' motor coordination in the chimney test. Some of the described pharmacological activities of compound 18 can be partly explained based on its affinity for plasma membrane GABA transporters.
authors.affiliation: Department of Physicochemical Drug Analysis, Jagiellonian University, Medical College, Kraków, Poland.
authors.forename: Kinga
authors.initials: K
authors.lastname: Sałat
authors.forename: Anna
authors.initials: A
authors.lastname: Więckowska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Więckowski
authors.forename: Georg C
authors.initials: GC
authors.lastname: Höfner
authors.forename: Jacek
authors.initials: J
authors.lastname: Kamiński
authors.forename: Klaus T
authors.initials: KT
authors.lastname: Wanner
authors.forename: Barbara
authors.initials: B
authors.lastname: Malawska
authors.forename: Barbara
authors.initials: B
authors.lastname: Filipek
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kulig
mesh_terms: D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D050485:GABA Plasma Membrane Transport Proteins / Q000378:metabolism*; D058805:GABA Uptake Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology*; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D000700:Analgesics; D014151:Anti-Anxiety Agents; D050485:GABA Plasma Membrane Transport Proteins; D058805:GABA Uptake Inhibitors; D026901:Membrane Transport Proteins; D005680:gamma-Aminobutyric Acid