J. Insect Physiol. Vol. 41, No. 7, pp. 565-570, 1995 zyxwvut 0022-1910(95)00013-5 Copyright c! 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0022-1910195 $9.50 + 0.00 Flight and Running Induce Elevated Levels of FMRFamide-related Peptides in the Haemolymph of the Cockroach, Periplaneta americana (L.) A. J. ELIA,* TOMAS G. A. MONEY,? I. ORCHARD? Received 29 September 1994; revised 8 December 1994 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA The appearance of FMRFamide-related peptides (FaRPs) in the haemolymph of the cockroach, Periplaneta americana (L.), during flight or running/righting behaviour was investigated using radioimmunoassay and reverse phase-HPLC. Both flight and running/righting behaviours caused an increase in the level of FaRPs measured in the haemolymph within the first minute of activity. Elevated levels (up to 18 times greater than control levels) persisted as long as animals continued the enforced activity (tested up to 15 min). After cessation of activity, levels of FaRPs in the haemolymph decreased to near-control levels in about 8-10 min. RP-HPLC indicated that FaRPs found in the haemolymph may have been released from thoracic ganglia or associated neurohaemal tissue. It is suggested that FaRPs released into the haemolymph during physical activity may play a role in modulating the contraction characteristics of heart and/or skeletal muscle. FaRPs Nervous system Skeletal muscle Neurohormones Blood Neuromodulator Neurohaemal INTRODUCTION The number of peptides recognized as members in the family of FMRFamide-related peptides (FaRPs) has grown enormously since the first description of FMRFamide (Phe-Met-Arg-Phe-NH2;Price and Green- berg, 1977). Along with the rapid growth in numbers of identified FaRPs is their acknowledged widespread distribution throughout the animal kingdom. Although several hypotheses have been proposed regarding the roles FaRPs play in both the nervous and muscular systems, one of the most tenable deals with the effects of FaRPs in the control/modulation of muscle contraction. For example, studies have shown that FaRPs have potent effects on contraction of heart muscle (Cuthbert and Evans, 1989; Duve et al., 1993), oviduct (Peeff et al., 1993), hindgut (Holman et al., 1986), and skeletal muscles of the legs (Evans and Myers, 1986; Elia and Orchard, 1995). In some cases, modulation of muscle contraction may be effected by direct innervation of the target tissue *To whom all correspondence should be addressed at Centre for Research in Neurodegenerative Diseases, Tanz Neuroscience Bldg., 6 Queen’s Park Cres. West, University of Toronto, Toronto, Ontario, Canada, M5S 11% TDepartment of Zoology, 25 Harbord Street, University of Toronto, Toronto, Ontario, Canada M5S lA8. (Duve et af., 1993; Elia and Orchard, 1995). However, there is evidence to suggest that FaRPs are also released from neurohaemal areas into the haemolymph from where they circulate as neurohormones to a distant target site (Robb and Evans, 1990; Elia et al., 1993). In the blood sucking insect, Rhodnius prolixus, it was shown that FaRPs were released into the haemolymph at specific times following a blood meal (Elia et al., 1993). In vitro, release of FaRPs from the corpora cardiaca of Manduca has also been demonstrated (Carroll et al., 1986), as well as the stimulation of the non-innervated salivary glands of Calliphora by endogenous calliFMRF- amides (Duve et al., 1992). FaRPs have also been reported present in the haemolymph of locusts at a wide range of concentrations (Robb and Evans, 1990). They suggested a role in modulation of muscle contraction since leg muscles of the locust appear to be sensitive to a variety of FaRPs. Furthermore, the possibility for the release of FaRPs into the haemolymph of the cockroach is suggested by the highly reactive immunopositive neurohaemal areas associated with nerves which emanate from the thoracic (and abdominal) ganglia (unpublished observations). In locust (Walther et ul., 1991), leech (Simon et al., 1994), squid (Cottrell et al., I992), and crayfish (Mercier et al., 1993), FaRPs have been shown to directly affect neuromuscular transmission. 565