Ivermectin is not an agonist at a GABA receptor in tick salivary glands

The avermectins, broad-spectrum anti-parasitic agents which are effective against ticks, act principally by stimulating -aminobutyric acid (GABA) receptors directly or indirectly. GABA is known to potentiate dopamine-induced fluid secretion in the salivary glands of female ixodid ticks. We thus tested wheter 10 M ivermectin would have an effect similar to GABA in the isolated salivary gland preparation ofDermacentor andersoni. Ivermectin was not an agonist at this GABA receptor.