4.1.2. Effects on the Central Nervous and Neuromuscular Systems

Behavior alterations consistent with a neurotoxic activity of Jaburetox in *T. infestans* [84] led our group to further investigate the effects on the insect's central nervous system. Immunohistochemical techniques evidenced the labelled somata of the antennal lobe and of the suboesophageal ganglion 3 h after the injection of the peptide into the hemocoel. Co-immunoprecipitation assays followed by tandem mass spectrometry identified the enzyme UDP-*N*-acetylglucosamine pyrophosphorylase as a Jaburetox-interacting protein in the bug's brain and associated ganglia [84]. This enzyme provides the

activated precursor for the synthesis of chitin and for glycosylation pathways of glycoproteins and other derived products [90].

The central nervous system was also a target for Jaburetox in the triatominae *R. prolixus*, and the interaction between the fluorescently-labeled peptide and the organ could be observed in vitro. Furthermore, the activities of different enzymes in the central nervous system were altered after feeding the peptide to fifth instar nymphs [78].

The interaction of Jaburetox with the nervous cord tissue of *N. cinerea* was observed in vitro [62]. Injection of the peptide into the cockroaches *Phoetalia pallida* and *N. cinerea* led to the blockade of evoked contractions of coxal muscle [58,85]. In *N. cinerea*, this effect was amplified by chloral hydrate, (a drug known to reinforce effects mediated by GABA receptors), suggesting that Jaburetox could be activating the gabaergic neurotransmission [85]. As reported in the kissing bugs, the enzymatic activities of several enzymes were modulated in adult cockroaches upon injection [86].

The effect of Jaburetox was tested on *Xenopus laevis* oocytes overexpressing the Nav 1.1 channels from the cockroach *Blatella germanica* [85]. Voltage-clamp analysis showed a 50% increase in the sodium currents upon Jaburetox treatment while no alteration in the kinetics of the Nav 1.1 channel activation was noticed. Muscle and nerve action potentials recorded in the isolated leg of the locust *Locusta migratoria* decreased transiently about 20% in Jaburetox-treated preparations, returning to basal values after 20 min although by then the contraction of the tarsus has stopped. The absence of a fast decrease in the resting membrane potential during the voltage clamp studies, especially considering the membrane-disturbing effects of Jaburetox, suggested that the main component of its neurotoxicity could involve alteration of the gating properties of sodium channels [85]. These aspects were recently reviewed by Barreto et al. [91].
