/ 2x10 2272 Mp 145 Tuesday Mar 25 01:32 PM EL–PEP (v.18#1) 2272 145 Peptides, Vol. 18, No. 1, pp. 145–156, 1997 Copyright  1997 Elsevier Science Inc. Printed in the USA. All rights reserved 0196-9781/97 $17.00 / .00 PII S0196-9781( 96 ) 00236-7 REVIEW Peptides in the Locusts, Locusta migratoria and Schistocerca gregaria 1 LILIANE SCHOOFS, 2 DIRK VEELAERT, JOZEF VANDEN BROECK AND ARNOLD DE LOOF Zoological Institute, Katholieke Universiteit Leuven, Naamsestraat 59, 3000 Leuven, Belgium Received 1 May 1996; Accepted 29 July 1996 SCHOOFS, L., D. VEELAERT, J. VANDEN BROECK AND A. DE LOOF. Peptides in the locusts, Locusta migratoria and Schistocerca gregaria: A review. PEPTIDES 18 (1) 145–156, 1997.—The first peptide identified in locusts was adipokinetic hormone I ( AKH-I ) , a neurohormone mobilizing lipids from the fat body. No other locust peptides were isolated until 1985. From then on peptide identification started to boom at such a tremendously fast rate that even specialists in the field could hardly keep track. At this moment the total number of different insect neuropeptide sequences exceeds 100. Currently, the locusts Locusta migratoria and Schistocerca gregaria are the species from which the largest number of neuropeptides has been isolated and sequenced, namely 56. Myotropic bioassays have played a major role in the isolation and subsequent structural characterization of locust neuropeptides. They have been responsible for the discovery of locustamyotropins [4], locustapyrokinins [2], locusta- tachykinins [5], locustakinin [1], locusta accessory gland myotropins [2], locustasulfakinin [1], cardioactive peptide [1], and locustamyoinhibiting peptides [ 4 ] . Members of the myotropin peptide families have been associated with a variety of physiological activities such as myotropic activities, pheromonotropic activities, diapause induction, stimulation of cuticular melanization, di- uresis, pupariation, and allatostatic activities. Recently, we have identified in Schistocerca 10 peptides belonging to the allatostatin peptide family, which inhibit peristaltic movements of the oviduct. Some of the myotropins appear to be important neurotrans- mitters or modulators innervating the locust oviduct, the salivary glands, the male accessory glands, and the heart, whereas others are stored in neurohemal organs until release in the hemolymph. Some myotropic peptides have been found to be releasing factors of neurohormones from the corpora cardiaca. Several peptides isolated in locusts appear to be unique to insects or arthropods; others seem to be members of peptide families spanning across phyla: two vasopressin-like peptides, FMRFamide-related peptides, Locusta diuretic hormone ( CRF-like ) , Locusta insulin-related peptide, locustatachykinins, locustasulfakinin ( gastrin / CCK-like ) . In a systematic structural study of neuropeptides in Locusta , several novel peptides have been isolated from the corpora cardiaca and the pars intercerebralis. They include the neuroparsins, two 6-kDa dimeric peptides, and three proteinase inhibitors. Ovary maturating parsin is the first gonadotropin identified in insects. The isolation of a peptide from an ovary extract that inhibits ovary maturation in Schistocerca gregaria is currently underway in our lab. The proteinase inhibitors, recently found to be mainly transcribed in the fat body, are believed to play a role in defense reactions of insects. Finally, a locust ion transport peptide and a peptide stimulating salivation recently identified can be added to this extensive list of locust peptides.  1997 Elsevier Science Inc. Locusta migratoria Schistocerca gregaria Peptides Neuropeptides Insect Endocrinology 1 Taken in part from a paper presented at a satellite symposium on Insect Neuropeptides during the Seventh Annual Neuropeptide Conference, February 1–6, 1996, Breckenridge, CO. 2 Requests for reprints should be addressed to Dr. Liliane Schoofs. Zoological Institute, Naamsestraat, 59, 3000, Leuven, Belgium ABOUT half a century ago Ernst and Berta Scharrer, the dis- coverers of neurosecretory cells, pointed to the structural sim- ilarity between the hypothalamo–hypophysial system of mammals and the pars intercerebralis–corpora cardiaca–cor- pora allata system of insects (102). Cauterization, implanta- tion, and stimulation of the pars intercerebralis unequivocally demonstrated the importance of neurosecretory cells in con- trolling a variety of physiological functions. Specific histolog- ical staining protocols such as Gomori and paraldehyde fuch- sin, allowed to distinguish different cell types. Electron microscopic investigations revealed that such cells contain neurosecretory vesicles. But the isolation and structural iden- tification of the active molecules contained in such vesicles remained very difficult for a long time. Only after major im- provements were realized in high performance liquid chro- matography and in peptide sequencing methods could the pu- rification of insect peptides be envisaged. Brown and Starrat realized in 1975 the first identification of an insect peptide, the pentapeptide proctolin (9). It was found to stimulate the motility of the proctodeum of Periplaneta americana . The second identified insect neuropeptide was adipokinetic hor- mone I (AKH I) from L. migratoria (130). This peptide is