(+)-Bicuculline, what does (+) mean?
Bicuculline is a chiral molecule.  That means that its mirror images are non-superimposable.  These non-superimposable images are termed "enantiomers."  When you see a "(+)" or "(-)" in front of a chemical name it tells you that only one the enantiomers is present (e.g. it is not a racemic mixture of the enantiomers).  Chiral molecules have the ability to rotate the plane of a polarized light beam that passes through it. Enantiomers will rotate the plane of polarization in exactly equal amounts (same magnitude) but in opposite directions.  

Dextrorotary designated as (+), indicates clockwise rotation (to the right)

Levorotary designated as (-), indicates anti-clockwise rotation (to the left)