TY - JOUR
T1 - Involvement of the opioid system in the hypokinetic state induced in cockroaches by a parasitoid wasp
AU - Gavra, Tali
AU - Libersat, Frederic
N1 - Funding Information:
Acknowledgments We thank Gustavo Glusman for technical assistance and Antonia Delago for valuable assistance and editorial comments. We also wish to thank one anonymous reviewer for making important suggestions to improve both the content and the writing of the original version of our manuscript. This work was supported by the Israel Academy of Sciences and Humanities (848/ 07). The experiments performed comply with Principles of Animal Care, NIH publication no. 86-23, revised in 1985, and also with the current laws of the State of Israel.
PY - 2011/3/1
Y1 - 2011/3/1
N2 - The parasitoid wasp Ampulex compressa stings and injects venom into the cockroach brain to induce a long-lasting hypokinetic state. This state is characterized by decreased responsiveness to aversive stimuli, suggesting the manipulation of a neuromodulatory system in the cockroach's central nervous system. A likely candidate is the opioid system, which is known to affect responsiveness to stimuli in insects. To explore this possibility, we injected cockroaches with different opioid receptor agonists or antagonists before they were stung by a wasp and tested the escape behavior of these cockroaches to electric foot shocks. Antagonists significantly decreased the startle threshold in stung individuals, whereas agonists led to an increased startle threshold in controls. Yet, neither agonists nor antagonists had any effect on grooming. To further characterize the interaction between the venom and opioid receptors, we used an antenna-heart preparation. In un-stung individuals external application of crude venom completely inhibits antenna-heart contractions. In stung individuals the antenna-heart showed no contractions. Although acetylcholine restored contractions, the opioid receptor antagonist naloxone was unable to antagonize the venom inhibition. These results suggest that the venom of A. compressa might contribute to the manipulation of cockroach behavior by affecting the opioid system.
AB - The parasitoid wasp Ampulex compressa stings and injects venom into the cockroach brain to induce a long-lasting hypokinetic state. This state is characterized by decreased responsiveness to aversive stimuli, suggesting the manipulation of a neuromodulatory system in the cockroach's central nervous system. A likely candidate is the opioid system, which is known to affect responsiveness to stimuli in insects. To explore this possibility, we injected cockroaches with different opioid receptor agonists or antagonists before they were stung by a wasp and tested the escape behavior of these cockroaches to electric foot shocks. Antagonists significantly decreased the startle threshold in stung individuals, whereas agonists led to an increased startle threshold in controls. Yet, neither agonists nor antagonists had any effect on grooming. To further characterize the interaction between the venom and opioid receptors, we used an antenna-heart preparation. In un-stung individuals external application of crude venom completely inhibits antenna-heart contractions. In stung individuals the antenna-heart showed no contractions. Although acetylcholine restored contractions, the opioid receptor antagonist naloxone was unable to antagonize the venom inhibition. These results suggest that the venom of A. compressa might contribute to the manipulation of cockroach behavior by affecting the opioid system.
KW - Ampulex compressa
KW - Antenna-heart
KW - Opioids
KW - Periplaneta americana
KW - Venom
UR - http://www.scopus.com/inward/record.url?scp=79951957312&partnerID=8YFLogxK
U2 - 10.1007/s00359-010-0610-9
DO - 10.1007/s00359-010-0610-9
M3 - Article
AN - SCOPUS:79951957312
SN - 0340-7594
VL - 197
SP - 279
EP - 291
JO - Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
JF - Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
IS - 3
ER -