Entomotoxic activity of Rhinella icterica (Spix, 1824) toad skin secretion in Nauphoeta cinerea cockroaches: An octopamine-like modulation.
Pestic Biochem Physiol
; 148: 175-181, 2018 Jun.
Article
de En
| MEDLINE
| ID: mdl-29891370
ABSTRACT
Rhinella icterica is a poisonous toad whose toxic secretion has never been studied against entomotoxic potential. Sublethal doses of Rhinella icterica toxic secretion (RITS) were assayed in Nauphoeta cinerea cockroaches, in order to understand the physiological and behavioral parameters, over the insect central and peripheral nervous system. RITS (10⯵g/g) injections, induced behavioral impairment as evidenced by a significant decrease (38⯱â¯14%) in the distance traveled (pâ¯<â¯.05), followed by an increase (90⯱â¯6%) of immobile episodes (pâ¯<â¯.001, nâ¯=â¯28, respectively). In cockroaches semi-isolated heart preparations, RITS (16⯵g/200⯵l) induced a significant irreversible dose-dependent negative chronotropism, reaching ~40% decrease in heart rate in 20â¯min incubation. In in vivo cockroach neuromuscular preparations, RITS (20, 50 and 100⯵g/g of animal weight) induced a time-dependent inhibition of twitch tension that was complete for 20⯵g/g, in 120â¯min recordings. RITS (10⯵g/g) also induced a significant increase in the insect leg grooming activity (128⯱â¯10%, nâ¯=â¯29, pâ¯<â¯.01), but not in the antennae counterparts. The RITS increase in leg grooming activity was prevented in 90% by the pretreatment of cockroaches with phentolamine (0.1⯵g/g). The electrophysiological recordings of spontaneous neural compound action potentials showed that RITS (20⯵g/g) induced a significant increase in the number of events, as well as in the rise time and duration of the potentials. In conclusion, RITS showed to be entomotoxic, being the neuromuscular failure and cardiotoxic activity considered the main deleterious effects. The disturbance of the cockroaches' behavior together with the electrophysiological alterations, may unveil the presence of some toxic components present in the poison with inherent biotechnological potentials.
Mots clés
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Peau
/
Toxines biologiques
/
Bufonidae
/
Octopamine
/
Blattes
Limites:
Animals
Langue:
En
Journal:
Pestic Biochem Physiol
Année:
2018
Type de document:
Article
Pays d'affiliation:
Brésil