Effects of a cyanobacterial extract containing-anatoxin-a(s) on the cardiac rhythm of Leurolestes circunvagans

Abstract

This work presents the effects of an anatoxin-a(s) containing extract on a cockroach semi-isolated heart preparation and the results supporting the extract's biological activity on acetylcholinesterase (purifi ed from eel). The presence of the toxin in cyanobacterial strains Anabaena spiroides (ITEP-024, ITEP-025 and ITEP-026) isolated from the Tapacurá reservoir in Pernambuco, Brazil, was confi rmed by means of liquid chromatography coupled to an ion-trap mass spectrometer. The anticholinesterase activity was assessed biochemically by the Ellman test and was confi rmed by measuring the cockroach's heart rate. The concentration of the extract containing the tested anatoxina(s) (antx-a(s)) (10, 16 and 100 μg.μL -1 ) inhibited the eel acetylcholinesterase (AChE) by more than 90%. The cockroach cardiac frequency increased by a maximum of about 20% within 29 min after the addition of 2.5x10 3 μg of extract containing antx-a(s).g -1 bw (n=9, p<0.05). Our results strongly indicate that antx-a(s) is capable of exerting biological effects on cockroach, indicating that more research might be conducted to determine its role in the environment, especially on insects.

Central and peripheral neurotoxicity induced by the Jack Bean Urease (JBU) in Nauphoeta cinerea cockroaches

“…In Periplaneta americana, the heart rate is determined by a neurogenic pace-maker with cholinergic properties (Wigglesworth, 1972), stimulated by ACh and by AChE inhibitors (Husmark and Ottoson, 1971a) (Husmark and Ottoson, 1971a) (Dahm, 1971;Husmark and Ottoson, 1971b). In a previous study, our group has demonstrated the increase of heart rate in Leurolestes circunvagans cockroaches by naturally occurring inhibitors of AChE (Rodríguez et al, 2012). The molecular mechanism(s) by which JBU leads to AChE inhibition was not investigated in the present work.…”

“…A semi-isolated cockroach heart bioassay was mounted essentially as described by Rodríguez et al, 2012. Briefly adult male cockroaches were anesthetized by chilling (5-7min) until immobile and placed ventral side up.…”

Entomotoxic Activity of Prasiola crispa (Antarctic Algae) in Nauphoeta cinerea Cockroaches: Identification of Main Steroidal Compounds

“…On the other hand, octopamine 1 receptors evokes the inhibition of cardiac rhythmic in insects [33,34]. Acetylcholine and AChE inhibitors also affect the heart rate in insects, inducing an increase or decrease of heart-beats, depending on the concentration [35,36,37]. Recently, our group have demonstrated the striking interaction between cholinergic-octopaminergic neurotransmission in N. cinerea [38].…”

The Insecticidal Activity of Rhinella schneideri (Werner, 1894) Paratoid Secretion in Nauphoeta cinerea Cocroaches

“…The activity of RSPS upon Nauphoeta cinerea cardiac rhythm was evaluated as described by Rodríguez et al [ 47 ], with a few modifications. Animals were previously anesthetized by chilling (5–7 min) and then fixed ventral side up on a dissection plate, were their viscera were carefully moved, allowing for cardiovascular system visualization.…”