Characterization and partial purification of different factors with contraction-potentiating activities from neurohaemal organs of the locust.

Phe-Met-Arg-Phe (FMRF-NH2) and structurally related peptides enhance neuromuscular transmission and contraction of the M. extensor tibiae preparations of the locusts Locusta migratoria and Schistocerca gregaria (Walther et al.: Neurosci. Lett. 45:99-104, '84). Similar effects could also be obtained with extracts of locust ganglia (Walther and Schiebe: Neurosci. Lett. 77:209-214, '87). By using two HPLC systems, we have partially purified extracts of the unpaired median nerves (including their neurohaemal organs) of different locust ganglia. The biological activity of the extracts served as an estimate for the degree of purification. Six different bioactive fractions were identified migrating at and close to retention times of known -RFamide peptides with similar bioactivity. No fraction coeluted with authentic FMRF-NH2 or FLRF-NH2. We demonstrate that extensor tibiae muscle contractions were potentiated by HPLC fractions from raw material with -RF-NH2 immunoreactivity, but also by HPLC fractions from raw material without such immunoreactivity.