Actions of thienyl analogs of baclofen at GABA(B) receptors in rat neocortical slices.

In rat neocortical slices maintained in Mg2+-free Krebs medium, baclofen and its thienyl analogs, 4-amino-3-(5-chlorothien-2-yl)-butanoic acid (5h), 4-amino-3-(5-methylthien-2-yl)-butanoic acid (5d), 4-amino-3-(5-bromothien-2-yl)-butanoic acid (5f) and 4-amino-3-(thien-3-yl)-butanoic acid (5j) dose-dependently suppressed the spontaneous discharges, antagonised by the GABA(B) receptor antagonist 2-hydroxysaclofen (200 microM). Their relative potencies were baclofen > 5h > 5d > 5f > 5j. These heterocyclic analogs may prove useful as GABA(B) receptor agonists in functional studies.