DISTRIBUTION OF SULFAKININ-LIKE PEPTIDES IN THE CENTRAL AND SYMPATHETIC NERVOUS-SYSTEM OF THE AMERICAN COCKROACH, PERIPLANETA-AMERICANA (L)AND THE FIELD CRICKET, TELEOGRYLLUS-COMMODUS (WALKER)

We describe the distribution of sulfakinin-like neuropeptides in the c entral and sympathetic nervous system of the American cockroach Peripl aneta americana (L.) (Blattodea) and the field cricket Teleogryllus co mmodus (Walker) (Orthoptera), using an antisulfakinin primary antibody and confocal laser scanning microscopy. We conclude that, in the cock roach, sulfakinin-like material is produced in ten pairs of anterior c ells in the pars intercerebralis, as well as two pairs of medial and o ne major pair of lateral posterior brain cells. This contrasts with fi ndings in other insects, including the cricket, where only the posteri or cell groups express sulfakinin-immunoreactive material. Extensive a rborization of dendrites containing sulfakinin-like peptides occurs wi thin the neuropile of both species, suggesting a neurotransmitted neur omodulator function. In the cockroach, there is clear evidence of dire ct distribution of sulfakinin-like peptides along axons to the foregut tissue, and a plexus of retrocerebral nerves is likely to serve as a neurohaemal release site. Neurohaemal release into the dorsal aorta is also postulated. Sulfakinin-immunoreactive axons do not innervate the hindgut in either cockroaches or crickets. Sulfakinin may function as a gut myotropin in the Blattodea, in addition to functioning as a neu rotransmitter within the central nervous system. This latter function appears to be general across insect orders, while the neurohaemal dist ribution and myotropic activity are restricted to the Blattodea.