THE EFFECT OF THE 13 DIP-ALLATOSTATINS ON MYOGENIC AND INDUCED CONTRACTIONS OF THE COCKROACH (DIPLOPTERA-PUNCTATA) HINDGUT

The Dip-allatostatins are a group of 13 neuropeptides, ranging in size from 6 to 18 amino acids, identified from a cloned cDNA sequence of D iploptera punctata, All 13 Dip-allatostatins inhibited both myogenic a nd proctolin-induced contractions of the hindgut of D, punctata. Dip-a llatostatins were capable of reducing a 5 x 10(-6) M proctolin-induced contraction in a dose-dependent manner, with ED(50) values ranging fr om 1.7 x 10(-7) M for Dip-allatostatin 7 to greater than 1.3 x 10(-5) M for Dip-allatostatin 12, The effects of the Dip-allatostatins were r eversible upon washing with saline, The free carboxylic acid (non-amid ated) form of Dip-allatostatin 11, callatostatin 3 and callatostatin 5 showed a loss of inhibitory activity, In contrast to the inhibitory a ctions of the Dip-allatostatins on hindgut contractions, selected Dip- allatostatins (Dip-allatostatins 4, 6, 7, 10, 12), at concentrations r anging from 10(-7) M to 2 x 10(-5) M, did not alter the frequency or a mplitude of myogenic contractions or inhibit proctolin-induced contrac tions of the cockroach oviduct muscle, Dip-allatostatins (Dip-allatost atins 1, 2, 4, 5, 6, 7) also had no effect on either myogenic or proct olin-induced contractions of the oviduct of Locusta migratoria.