Nanoinjection of neurotransmitters into the prothoracic ganglion of female cricket Acheta domesticus changes phonotactic selectivity

The phonotactic response by female crickets is influenced by Juvenile Hormone III, which affects selectivity to the syllable period of the calling song. This pathway is influenced by an inhibitory input in the prothoracic ganglion, possibly chloride-mediated inhibition. In order to identify potential neurotransmitters involved in such pathway, we performed nanoinjection of five neurotransmitters into the prothoracic ganglion of virgin female Acheta domesticus. Phonotaxis for these females was evaluated before and after injections. All five neurotransmitters that were nanoinjected are known to bind to chloride channels. Nanoinjection of histamine significantly decreased phonotactic selectivity to the syllable period of the calling song while glycine, gamma aminobutyric acid, serotonin and saline controls did not. Octopamine significantly decreased phonotactic responses overall. The effect of histamine was tested further by nanoinjecting the antihistamine pyrilamine into the prothoracic ganglion of older unselected females, which resulted in increased phonotactic selectivity.