Influência Da Urease De Canavalia Ensiformis Sobre O Sistema Cardiovascular De Nauphoeta Cinerea

Abstract

Studies with cockroaches have been motivated by interest in the development of new agents with natural insecticide activity as well as in pharmacological essays for development of new herapeutic agents. Canavalia ensiformis’ Urease (Jack Bean Urease, JBU) has been characterized as a natural insecticide. Although its effect on the peripheral nervous system of insects have already been demonstrated, it has not been demonstrated their activity on other systems as for example, cardiovascular. In this sense, the aim of this study was to investigate the activity induced by JBU on the modulation of heart rate cockroaches of the species Nauphoeta cinerea using the preparation in vivo semi-isolated heart.Thus, in this work were used both sexes of cockroaches, adults from Nauphoeta cinerea species were housed in temperaturecontrolled insectary (22-24ºC), and water and feed ad libitum. To assemble the cockroaches preparation were anesthetized by cooling (-20 ºC for 10 minutes) and affixed with entomological pins on a plate coated with Styrofoam with ventral region facing up. The cuticle that covers the abdomen was removed with the aid of an ophthalmic scissors, visceral organs removed carefully with tweezers to visualize the vascular system. Then, the animal was placed under a magnifying glass with an increase of 60X and heartbeat visually accounted for 30min. In the control experiments only with the addition of saline heart rate of the animals was 120 ± 90 beats / min (n = 9). When JBU (1.5, 3.0 and 6 μg /g animal) was incubated, induced positive chronotropic effect that was 94 ± 5bat. / min and 125 ± 3bat. / min with the administration of JBU (3 μg /g animal) having a mean increase of 20 ± 4% in heart rate when compared with the saline control (p <0.05, n = 9). In this series of experiments the addition of neostigmine mimicked the positive chronotropic effect of urease which was also inhibited by atropine, a known anticholinergic compound. Acetylcholine had a positive chronotropic effect of 35 ± 6% higher compared to the saline control. The results suggest that the urease Canavalia ensiformis is able to modulate the heart rate of N.cinerea. The positive chronotropic effect is counteracted by atropine, an inhibitor of muscarinic receptors, suggesting a peptide interaction with this receptor. Thus, this study reinforces the biotechnological potential of Canavalia ensiformis urease, demonstrating the influence of this compound on the cholinergic system of cockroaches.