THE INSECT NEUROPEPTIDE CORAZONIN - PHYSIOLOGICAL AND IMMUNOCYTOCHEMICAL STUDIES IN BLATTARIAE

The physiological effects of the insect cardioactive peptide corazonin on visceral muscles of Blattariae were studied. In Periplaneta americ ana heart, hyperneural muscle and antennal heart were found to be high ly sensitive to corazonin, whereas the oviduct and proctodeum showed n o response. Furthermore the corazonin sensitivy of heart, hyperneural muscle and antennal heart in eight other cockroach species was investi gated. In contrast to common opinion, we found that in general the hyp erneural muscle appears to be present in Blattariae. Surprisingly, the specific effectiveness of corazonin on visceral muscles turned out to be largely restricted to Periplaneta, although this neuropeptide had also been biochemically detected in insects of other taxa. The distrib ution of corazonin-like immunoreactivity in the brain of Periplaneta a mericana was examined in detail and compared with the situation in ano ther cockroach, Leucophaea maderae. The results indicate that the neur osecretory part of the corazonin system is a well conserved structure among the Blattariae. Therefore, we suppose that further natural targe ts of this insect hormone exist that have not yet been discovered.