Effects of manganese (Mn2+) on neurotoxic and myotoxic activities induced by Crotalus durissus terrificus and Bothrops jararacussu venoms in chick biventer cervicis preparations

Abstract

In the present study, manganese (Mn2+), a neuromuscular blocker with pre and postsynaptic actions, was used to verify the neurotoxicity and myotoxicity induced by Crotalus durissus terrificus (Cdt) and Bothrops jararacussu (Bjssu) venoms in biventer cervicis preparations (BCp). Preparations pretreated with 0.66 and 1.6mM Mn2+ did not affect Cdt venom-induced blockage nor change KCl-induced contracture but partially reduced ACh-induced contracture. However, both Mn2+ concentrations partially hindered Bjssu venom-induced blockage after washing the preparations with Krebs solution, and only 1.6mM Mn2+ preparations significantly recovered ACh-induced contracture. The effect of Cdt venom myotoxicity on contractile responses was different from that of Bjssu venom myotoxicity. Pretreatment with 1.6mM Mn2+ partially reduced muscle damage percentage and creatine kinase (CK) activity (U/l) induced by both venoms. In conclusion, Mn2+ interfered in ACh-induced contracture of the nicotinic receptor; did not prevent Cdt venom neurotoxicity but partially reduced its myotoxicity in vitro due to the stabilizing action of this venom on the sarcolemmal membrane; and partially attenuated myotoxicity and neuromuscular blockage induced by Bjssu venom. The Mn2+ dual action (pre and postsynaptic) is useful to study snake venoms since most of them present one or both of these actions; besides, Mn2+ allowed recovering coherent interpretation of experimental versus clinical results

Heparin and commercial bothropic antivenom against the paralyzing effect of Bothrops jararacussu snake venom

“…As examples of venom or toxin neutralization, many other substances have been assayed, ranging from manganese salt, which provides significant protection against Bjssu venom and its toxin neurotoxicity, to medicinal plants, as shown by hydroalcoholic extract of Casearia sylvestris against the neuromuscular paralyzing effect of BThTX-I (31)(32)(33). Therefore, new therapies in parallel with the antivenom treatment would be fundamental in minimizing local effects induced by snake venoms, specially those from the Bothrops genus (30).…”

A Comparison between Neuromuscular Effects of Parathion and Paraoxon on Chick Biventer Cervicis Nerve-Muscle and the Reversal of their Effects by Pralidoxime

“…The modified Krebs-Henseleit solution was composed of (mM): NaCl, 118.4; KH2PO4, 1.2; glucose, 11.1; NaHCO3, 25; CaCl2, 2.5; MgSO4, 1.4 and KCl, 4.7 (14). As described by Khodaei et al (2004), in twitch tension recording, twitches were evoked by stimulating the motor nerve at 0.1 Hz with pulses 0.2 msec duration and a voltage greater than that required to produce the maximum response (15).…”

Insights of the effects of polyethylene glycol 400 on mammalian and avian nerve terminals

“…Two‐micron‐thick sections, obtained using a microtome (RM 2035; Leica Instruments GmbH, Nubloch/Heidelberg, Germany), were stained with 0.5% toluidine blue for examination under light microscopy (Olympus Optical Co., Ltd., Tokyo, Japan). The extent of muscle damage was qualitatively and quantitatively assessed by counting 70 fibers (normal and damaged) in four non‐overlapping areas from a total of 280 fibers per preparation in control and treated preparations ( n = 3 each) 13. Morphological changes, such as dark edematous, hypercontracted cells with sarcolemma rupture, or ghost cells, were considered myofibers affected by the treatment.…”