THE BLOOD LEVELS OF GLUCAGON, CORTISOL, AND INSULIN FOLLOWING THE INJECTION OF VENOM BY THE SCORPION (Mesobuthus tamulus concanesis, POCOCK) IN DOGS

A Novel Therapeutic Formulation for the Improved Treatment of Indian Red Scorpion (Mesobuthus tamulus) Venom-Induced Toxicity-Tested in Caenorhabditis elegans and Rodent Models

Indian Red Scorpion (Mesobuthus tamulus) stings are a neglected public health problem in tropical and sub-tropical countries, including India. The drawbacks of conventional therapies using commercial anti-scorpion antivenom (ASA) and α1-adrenoreceptor antagonists (AAA) have prompted us to search for an adequate formulation to improve treatment against M. tamulus stings. Novel therapeutic drug formulations (TDF) of low doses of commercial ASA, AAA, and ascorbic acid have remarkably improved in neutralising the in vivo toxic effects of M. tamulus venom (MTV) tested in Caenorhabditis elegans and Wistar strain albino rats in vivo models. The neutralisation of MTV-induced production of free radicals, alteration of the mitochondrial transmembrane potential, and upregulated expression of genes involved in apoptosis, detoxification, and stress response in C. elegans by TDF surpassed the same effect shown by individual components of the TDF. Further, TDF efficiently neutralized the MTV-induced increase in blood glucose level within 30 to 60 min post-treatment, organ tissue damage, necrosis, and pulmonary oedema in Wistar rats, indicating its clinical application for effecting treating M. tamulus envenomation. This study demonstrates for the first time that C. elegans can be a model organism for screening the neutralization potency of the drug molecules against a neurotoxic scorpion venom.

Interleukin-1 Receptor-Induced Nitric Oxide Production in the Pancreas Controls Hyperglycemia Caused by Scorpion Envenomation

Tityus serrulatus causes numerous scorpion envenomation accidents and deaths worldwide. The symptoms vary from local to systemic manifestations, culminating in pulmonary edema and cardiogenic shock. Among these events, transitory hyperglycemia is a severe manifestation that influences pulmonary edema, hemodynamic alterations, and cardiac disturbances. However, the molecular mechanism that leads to increased glucose levels after T. serrulatus envenomation remains unknown. This study aimed to investigate our hypothesis that hyperglycemia due to scorpion envenomation involves inflammatory signaling in the pancreas. The present study showed that T. serrulatus venom induces the production of IL-1α and IL-1β in the pancreas, which signal via IL-1R and provoke nitric oxide (NO) production as well as edema in β-cells in islets. Il1r1^−/− mice were protected from transitory hyperglycemia and did not present disturbances in insulin levels in the serum. These results suggest that the pathway driven by IL-1α/IL-1β-IL-1R-NO inhibits insulin release by β-cells, which increases systemic glucose concentration during severe scorpion envenomation. A supportive therapy that inhibits NO production, combined with antiserum, may help to prevent fatal outcomes of scorpion envenomation. Our findings provide novel insights into the design of supportive therapy with NO inhibitors combined with antiscorpion venom serum to overcome fatal outcomes of scorpion envenomation.

Incidence, mechanisms and impact outcome of hyperglycaemia in severe scorpion-envenomed patients

Hyperglycaemia is often observed in severe scorpion-envenomed patients. It is due to a severe autonomic storm with a massive release of catecholamines, increased glucagon levels, cortisol levels, and either decreased insulin levels or insulin resistance. The presence of hyperglycaemia is an indicator of severity in this specific condition. Indeed, hyperglycaemia was associated with the severity of clinical manifestations of severe scorpion envenomation requiring intensive care unit (ICU) admission. In fact, the presence of hyperglycaemia was associated with the presence of respiratory failure, pulmonary oedema, haemodynamic instability, neurological failure, multisystem organ failure, and an increased mortality and ICU length of stay. As a consequence, we think the presence of hyperglycaemia in scorpion-envenomed patients at the emergency department prompts searching for presence of systemic manifestations or cardiorespiratory manifestations. As a consequence, the presence of hyperglycaemia can help screen severe patients at the emergency department. The current management of severe scorpion envenomation involves the admission and close surveillance in the ICU, where vital signs and continuous monitoring enable early initiation of therapy for life-threatening complications. The use of antivenom for scorpion stings remains controversial. All patients with pulmonary oedema should receive prazosin and possibly dobutamine, according the scorpion's species. Mechanical ventilation is usually used in severe cases. Insulin should be reserved for severe cases with confirmed excessive hyperglycaemia (>10 mmol/l).

Impact of scorpion venom as an acute stressor on the neuroendocrine-immunological network

Although immunomodulatory property and many other pharmaceutical applications of scorpion venom have been addressed before, no studies were reported about its application as a neuroimmunomodulator at therapeutic dose. In this study, we conceptualized the property of scorpion venom, capable of inducing the acute pain and neurotoxicity can cause acute stress resulting in the modulation of immune cells through HPA axis. The whole venom from Hottentotta rugiscutis, a widely seen scorpion in the region of eastern Karnataka, was extracted and injected a single dose of 1 mg/kg b.w. to Swiss albino mice and then erythrocytes and leukogram were measured. Whole brain AChE activity, corticosterone, cytokines and NO levels in plasma were also evaluated at various time points. Hrv didn't show any histopathological changes in the lymphoid organs and at the site of injection. However, lymphocytes and neutrophils did get altered at 2 h post-injection. Plasma corticosterone, cytokine levels such as IL-1β, IL-6, TNF-α and IL-10 and the AChE activity were significantly increased in a time-dependent manner. Based on these results, it may be predicted, Hrv's ability to cause acute stress resulted in the activation of HPA axis, which stimulates the release of glucocorticoid hormones which in turn elicits the immunomodulation of leukocytes by altering the levels of pro and anti-inflammatory cytokines. Thus, we can conclude, the impact of acute stress induced by Hrv can intercommunicate the signals between neuroendocrine-immune systems.

Tityus serrulatus envenoming in non-obese diabetic mice: a risk factor for severity

BACKGROUND

In Brazil, accidents with venomous animals are considered a public health problem. Tityus serrulatus (Ts), popularly known as the yellow scorpion, is most frequently responsible for the severe accidents in the country. Ts envenoming can cause several signs and symptoms classified according to their clinical manifestations as mild, moderate or severe. Furthermore, the victims usually present biochemical alterations, including hyperglycemia. Nevertheless, Ts envenoming and its induced hyperglycemia were never studied or documented in a patient with diabetes mellitus (DM). Therefore, this is the first study to evaluate the glycemia during Ts envenoming using a diabetic animal model (NOD, non-obese diabetic).

METHODS

Female mice (BALB/c or NOD) were challenged with a non-lethal dose of Ts venom. Blood glucose level was measured (tail blood using a glucose meter) over a 24-h period. The total glycosylated hemoglobin (HbA1c) levels were measured 30 days after Ts venom injection. Moreover, the insulin levels were analyzed at the glycemia peak.

RESULTS

The results demonstrated that the envenomed NOD animals presented a significant increase of glycemia, glycosylated hemoglobin (HbA1c) and insulin levels compared to the envenomed BALB/c control group, corroborating that DM victims present great risk of developing severe envenoming. Moreover, the envenomed NOD animals presented highest risk of death and sequelae.

CONCLUSIONS

This study demonstrated that the diabetic victims stung by Ts scorpion should be always considered a risk group for scorpion envenoming severity.

Mesobuthus tamulus venom induces acute respiratory distress syndrome in rats involving additional mechanisms as compared to oleic acid model

The present study was undertaken to determine whether acute respiratory distress syndrome (ARDS) is produced after Mesobuthus tamulus (MBT) envenomation and compared it with oleic acid (OA)-induced ARDS. The trachea, jugular vein and femoral artery were cannulated in anesthetized adult rats. Lethal dose of MBT venom (5 mg/kg) or OA (75 μL) was administered intravenously and the time-dependent changes in respiratory frequency (RF), heart rate (HR) and mean arterial pressure (MAP) were recorded. Minute ventilation (MV) and the PaO2/FiO2 (P/F) ratio were also determined. At the end lungs were excised, one lung was used for histopathological examination and the other was used for determination of pulmonary water content physically. MBT venom or OA produced hypoxemia, pulmonary pathology (alveolar damage, infiltration of inflammatory cells, capillary damage and exudation) and pulmonary edema implicating for ARDS. However, the hypoxemia in MBT venom group was associated with decreased MV, apnea/bradypnea, and bradycardia whereas, in OA group it was seen with increased MV, tachypnea, and tachycardia. Lack of effect of hypoxemic drive on RF/MV or HR in MBT venom group unlike OA group, suggests the involvement of medullary centers. The present results demonstrate that MBT venom produces ARDS. However MBT venom-induced ARDS involves pulmonary as well as extrapulmonary mechanisms.

Hematological and biochemical profiles of rats submitted to experimental poisoning with Tityus serrulatus venom

The hematological and biochemical profiles of newly weaned rats submitted to experimental poisoning with T. serrulatus venom were evaluated. Fifteen recently weaned male Wistar rats (mean weight 130g) were distributed into three equal groups (n = 5). Animals in the control group (group A) received a subcutaneous injection of 400μL of ultra-pure water, while those in the experimental groups received, by identical route, 400μL of a solution containing 100μg (group B) or 450μg (group C) of scorpion venom dissolved in ultra-pure water. Red blood cells indexes, and differential leukocyte and total platelet counts were determined, together with levels of serum glucose, urea, creatinine, lactic dehydrogenase, aspartate aminotransferase, amylase, insulin, and cortisol. No significant differences between the control and experimental groups regarding red blood cells indexes were found. In contrast, significant increases (P<0.05) in neutrophils, lymphocytes, and monocytes were observed in animals from groups B and C compared with the control group, while the number of platelets decreased. Serum glucose concentration remained unchanged in all groups, but important alterations were observed in the values of urea and creatinine. The results show that scorpion venom was detrimental to renal function as demonstrated by the altered urea and creatinine levels. Pancreatic function was also impaired, as revealed by the increase in amylase activity and the reduction in insulin levels.

Effects of Tityus serrulatus scorpion venom on lung mechanics and inflammation in mice

The present study evaluated the effects of an intramuscular injection of Tityus serrulatus venom (TsV) (0.67 miocrog/g) on lung mechanics and lung inflammation at 15, 30, 60 and 180 min after inoculation. TsV inoculation resulted in increased lung elastance when compared with the control group (p < 0.001); these values were significantly higher at 60 min than at 15 and 180 min (p < 0.05). Resistive pressure (DeltaP1) values decreased significantly at 30, 60 and 180 min after TsV injection (p < 0.001). TsV inoculation resulted in increased lung inflammation, characterised by an increased density of mononuclear cells at 15, 30, 60 and 180 min after TsV injection when compared with the control group (p < 0.001). TsV inoculation also resulted in an increased pulmonary density of polymorphonuclear cells at 15, 30 and 60 min following injection when compared to the control group (p < 0.001). In conclusion, T. serrulatus venom leads to acute lung injury, characterised by altered lung mechanics and increased pulmonary inflammation.

Insulin-like effects of Bauhinia forficata aqueous extract upon Tityus serrulatus scorpion envenoming

Scorpion envenoming causes an intense autonomic discharge, leading to a massive release of neurotransmitters, giving rise to several pathophysiological effects. In this work we report the effects of a Bauhinia forficata aqueous extract (BfAE) upon hyperglycemia, glycogenolysis, increase of plasma catecholamines, lethality and changes in serum insulin and plasma electrolytes induced by Tityus serrulatus scorpion venom (TSV). We compare them with the effects of the regular insulin therapy. The following treatments were performed: TSV (500 microg/kg, i.p.); BfAE (1g/kg, p.o.), 24, 12 and 1 h before and immediately after TSV or saline and insulin in a single dose (1.5 IU/kg, s.c.) after TSV. BfAE reduces the fast hyperglycemia induced by TSV, but it is deprived of hypoglycemic activity. The extract also did not reduce either the intense glycogenolysis or the release of catecholamines and did not stimulate the release of endogenous insulin, although causing changes in the electrolyte plasma levels similarly to insulin. Although BfAE and insulin antagonize some effects of TSV, they should be avoided in the treatment of Tityus serrulatus envenoming, since they enhance the lethality of the venom.