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Updated: Jun 28, 2026
Electrophysiology of Scorpion Peg Sensilla
Published on: April 13, 2011
Electroencephalographic evidence of brainstem recruitment during scorpion envenomation
Patrícia Alves Maia Guidine1, Michel Bernanos Soares Mesquita, Tasso Moraes-Santos
1Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270 901 Belo Horizonte, Minas Gerais, Brazil.
Insights
Scorpion venom toxin (TsTX) primarily affects the brainstem
Area of Science:
- Neuroscience
- Toxicology
- Public Health
Background:
- Scorpion envenomation, particularly by Tityus serrulatus scorpion venom (TSSV), poses a significant public health risk, especially for young children.
- The central nervous system's role in scorpion envenomation morbidity is debated, despite reported electroencephalogram (EEG) alterations in severe pediatric cases.
- Toxic fractions of TSSV exhibit greater blood-brain barrier permeability in young rats compared to adults.
Purpose of the Study:
- To investigate the hypothesis that neural substrates crucial for morbidity generate activity undetectable by scalp EEG leads.
- To explore the early central nervous system (CNS) effects of tityustoxin (TsTX), a potent toxin from TSSV.
- To assess the impact of carbamazepine (CBZ) on TsTX-induced neural and cardiac alterations.
Main Methods:
- Twenty-one-day-old rats were injected with TsTX (2xDL50).
- EEG leads were stereotaxically implanted in the nucleus of the solitary tract (NTS) and parietal cortex.
- Continuous EEG and electrocardiogram (ECG) monitoring was performed, with a carbamazepine-treated group included.
Main Results:
- High-amplitude NTS discharges, correlating with cardiac alterations, were observed shortly after TsTX administration.
- Cortical abnormal electrographic activity emerged later, indicating initial brainstem involvement.
- Carbamazepine treatment delayed epileptiform discharges, reduced EEG/ECG alterations, and prolonged survival.
Conclusions:
- Peripheral TsTX inoculation activates brainstem areas involved in cardiovascular control.
- Early electrographic activity related to TsTX envenomation is primarily brainstem-mediated and undetectable by cortical electrodes.
- These findings highlight the critical role of the brainstem in the pathophysiology of severe scorpion envenomation.
Abstract:
Scorpion envenomation is a public health problem in Brazil, with most severe cases occuring in children under the age of 5 years (0.6% lethality). In fact, the toxic fractions of the Tityus serrulatus scorpion venom (TSSV) have greater permeability across the BBB of weanling rats when compared to adults. Although EEG alterations have been reported in up to 75% of pediatric severe cases, the role of the CNS in envenomation morbidity is still in debate. Our working hypothesis is that the neural substrates that play a major role in morbidity generate activity undetectable from EEG scalp leads. Twenty one-day-old rats (n=18) were injected s.c. with the deadliest toxic fraction of the TSSV, tityustoxin (TsTX; 2xDL50=6 mg/kg). EEG leads were stereotaxicaly implanted in the nucleus of the solitary tract (NTS) and left parietal cortex. EEG and ECG were continuously monitored by a video EEG system until death or for a maximum period of 240 min. An experimental group pre-treated with carbamazepine (CBZ) was added in order to better access the cause-effect relationship between neural discharges and the systemic ECG alterations. High amplitude discharges in the NTS, which correlated to cardiac alterations, were recorded soon after administration of TsTX. Abnormal electrographic activity spread throughout the cortex only later in the recording. As expected, the CBZ treatment increased the latency for the first epileptiform discharge, decreased EEG/ECG alterations and increased the general survival time. In summary: peripheral scorpion toxin inoculation recruits brainstem involved in cardiovascular control and initial electrographic activity was undetectable from the cortical electrode.
