Led-NPF-1 stimulates ovarian development in locusts

For more than a decade, immunohistochemical results on FMRFamide related pe ptides (FaRP's) have been reported extensively, suggesting many possible ro les for these peptides associated with behavioural and physiological events as well as reproduction. This study provides a clear effect in vivo of mem bers of this family of insect neuropeptides. The effect of two neuropeptide F-related peptides from the Colorado potato beetle, Leptinotarsa decemline ata, Led-NPF-1 and Led-NPF-2 as well as the locusts myotropins, Lom-PK-1, L om-PK-2 and Lom-SK, was screened in an ovarian development assay in the Afr ican migratory locust and the grey fleshfly, Neobellieria bullata. Led-NPF- 1 (Ala-Arg-Gly-Pro-Gln-Leu-Arg-Leu-Arg-Phe-NH2) was shown to be a potent go nadostimulin in Locusta migratoria, but not in Neobellieria bullata. A mini mal dose of 0.05 mu g of Led-NPF-1 per animal, every 12 h, during 5 consecu tive injections into 6 day old virgin females, could accelerate egg develop ment. Higher doses of prolonged injections were demonstrated to be even mor e potent in the ovarian development assay. Led-NPF-2 (Ala-Pro-Ser-Leu-Arg-L eu-Arg-Phe-NH2) was far less active. The other tested peptides scored no re producible effect what so ever on ovarian growth, in locusts, nor in flies. The gonadotropic action of a NPF-like peptide on oocyte growth implies a c omplex regulation of oogenesis in the locust and adds to our knowledge of i nsect neuroendocrinology in general. The results also suggest that a peptid e of similar sequence also resides in the locust. (C) 1999 by Elsevier Scie nce Inc.