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 gamma-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 whether 10 microM ivermectin would have an effect similar to GABA in the isolated salivary gland preparation of Dermacentor andersoni. Ivermectin was not an agonist at this GABA receptor.