LOCUSTATACHYKININ IMMUNOREACTIVITY IN THE BLOWFLY CENTRAL-NERVOUS-SYSTEM AND INTESTINE

An antiserum raised against locustatachykinin I, one of four myotropic peptides that have been isolated from the locust brain and corpora ca rdiaca, was characterized by enzyme-linked immunosorbent assay (ELISA) and used for immunocytochemical detection of neurons and endocrine ce lls in the nervous system and intestine of the blowfly Calliphora vomi toria. The ELISA characterization indicated that the antiserum recogni zes the common C-terminus sequence of the locustatachykinins I-III. He nce, the cross reaction with locustatachykinin TV is less, and in comp etitive ELISAs no cross reaction was detected with a series of vertebr ate tachykinins tested. It was also shown that the antiserum recognize d material in extracts of blowfly heads, as measured in ELISA. In high -performance liquid chromatography the extracted locustatachykinin-lik e immunoreactive (LomTK-LI) material eluted in two different ranges. A fairly large number of LomTK-LI neurons was detected in the blowfly b rain and thoracicoabdominal ganglion. A total of about 160 LomTK-LI ne urons was seen in the proto-, deuto-, and tritocerebrum and subesophag eal ganglion. Immunoreactive processes from these neurons could be tra ced in many neuropil regions of the brain: superior and dorsomedian pr otocerebrum, optic tubercle, fan-shaped body and ventral bodies of the central complex, all the glomeruli of the antennal lobes, and tritoce rebral and subesophageal neuropil. No immunoreactivity was seen in the mushroom bodies or the optic lobes. In the fused thoracicoabdominal g anglion, 46 LomTK-LI neurons could be resolved. The less evolved larva l nervous system was also investigated to obtain additional informatio n on the morphology and projections of immunoreactive neurons. In neit her the larval nor the adult nervous systems could we identify any eff erent or afferent immunoreactive axons or neurosecretory cells. The wi despread distribution of LomTK-LI material in interneurons suggests an important role of the native peptide(s) as a neurotransmitter or neur omodulator within the central nervous system. Additionally a regulator y function in the intestine is indicated by the presence of immunoreac tivity in endocrine cells of the midgut. (C) 1991 Wiley-Liss, Inc.