Abstract
BACKGROUND AND PURPOSE Ionotropic GABA receptors (GABARs) in insects are
the major inhibitory receptor and common targets in insecticides for
pest control. Due to their high spatiotemporal resolution, the
photopharmacological ligands have been developed in vertebrates, but
only a few in insect yet. EXPERIMENTAL APPOACH In this study, two types
of photoswitchable ligands (PCLs) by incorporating photoswitch
azobenzene or dithienylethene into the antagonist, fipronil (FIP)
generated the DTFIPs (DTFIP1 and DTFIP2) and ABFIPs (p-, m-, and
o-ABFIP). Their photomodulation was measured by mosquito larval
behavior, and the potential action mechanism of them was explored by
two-electrode voltage clamp (TEVC) technique in vitro. KEY RESULTS
DTFIP1 and m-ABFIP exhibited biggest difference of insecticidal activity
between unirradiated and irradiated formation, and allowed for optical
control of insect locomotors activity in swimming. The TEVC assay
results indicted m-ABFIP and DTFIP1 enable optical control over the
homomeric RDL-type GABAR, which is achieved by regulating the chloride
channel of insect resistance to RDL-type GABAR by photoisomerization.
CONSLUSION AND IMPLICATIONS Our results suggested that PCLs provide an
alternative and precise tool for studying insect ionotropic GABARs and
GABA-dependent behavior.