Proctolin in the brain and ganglia of Triatoma infestans (Hemiptera : Reduviidae)

The distribution of proctolin in the central nervous system of the hemipter an bug, Triatoma infestans, was studied by immunohistochemistry using the s ensitive avidin-biotin technique combined with nickel salt intensification of the reaction product. Proctolin was present in cells and fibers of the b rain and ganglia. In the brain, protocerebral proctolin-immunoreactive cell bodies were found in the pars intercerebralis, the optic lobes, and the la teral soma rind. The deutocerebrum showed positive somata in relation to th e antennal motor center and the tritocerebrum had intense immunoreactive fi bers but few positive cells. Proctolin-immunoreactive cell bodies of different sizes were observed in th e subesophageal ganglion. Large cell bodies were found mainly rostrally and beaded positive processes were present around the ventral border of the es ophageal foramen and in the rostrolateral neuropil of this ganglion. Small- to medium-sized positive somata were found in the posterior part of the prothoracic ganglion; some of these cells were sending immunoreactive p rocesses to the central neuropil. The meso -metathoracic- abdominal ganglio nic mass showed positive cells in all the neuromeres, where some of them we re large and had thick immunoreactive granules. The results show that the labeling pattern of proctolin-like immunoreactivi ty in Triatoma i. appears to be widespread and unique for its central nervo us system. It is suggested that proctolin may serve neuroendocrine, integra tive, and motor functions in the brain of T infestans. J. Morphol. 240:39-4 7, 1999. (C) 1999 Wiley-Liss, Inc.