A forward to optimization of antivenom therapy: An in vivo study upon the effectiveness of the antivenom against early and delayed nephrotoxicity induced by the venom of the Iranian scorpion Hemiscorpius lepturus in rat.

The aim of the present in vivo study was to identify the optimal effective dose, the most favorable time and the route of administration of the available polyvalent scorpion antivenom against the toxic effects induced by Hemiscorpius lepturus (H. lepturus) venom in rat. The end point for assessment included measurement of alanin-amino-peptidase (AAP) and N-acetyl-b-d-glucosaminidase (NAG), biochemical urine analysis and histopathological assessment. The results showed that a single subcutaneous 50 µg of the venom produced significant increase in the AAP and NAG enzyme activity, urinary biochemical parameters and induced histopathological structural abnormalities in the renal system. The optimal effective co-administered dose of the antivenom was 0.5 ml, which when administered 1 and 2 h of envenomation by intravenous (IV) and subcutaneous (SC) routes respectively produced significant protection against these toxic effects. Prudently, the significance of these findings need to be assessed in further clinical studies.

In vitro and in vivo studies on some toxic effects of the venom from Hemiscorpious lepturus scorpion.

The aim of this laboratory-based study was to investigate some of the toxic effects induced by the venom from Hemiscorpious lepturus (H. lepturus). For this aim, pharmacological, histological, biochemical methods as well as complete blood cell count were used to assess these toxic actions. In addition, in vitro haemolysis studies on human washed blood suspension and cytotoxicity on cultured fibroblasts were also undertaken. In vitro pharmacological test was made on rat isolated ileal segment. To this end, the effects of the venom on the contractile responsiveness to acetylcholine were recorded using F30 transducer and Darco chart recorder. For assessment of the haemolytic potency, varying concentrations (2, 10, 20 and 40 microg/ml) of the venom were added to 0.5 ml of 5% washed human blood and after 30 min, 2, 4, 8, 12 and 24h of exposure, the degree of lysis (extent of redness developed in the supernatant solution after centrifugation) were measured by ELISA method. Cytotoxicity potential of the venom was assessed by trypan blue exclusion test. The venom (0.1, 1 and 10 microg/ml) was mixed with confluent fibroblast cell culture and the extent cytotoxicity was assessed microscopically. In vivo studies were conducted by a subcutaneous administration of sub-lethal dose (10 microg) of the venom and after 7 days the skin, at the site of injection, and kidney samples were stained by H & E method and examined microscopically. In addition, biochemical assessments including measurement of serum aspartate aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and amylase levels and urine analysis were made. The results showed that the venom prevented the relaxation phase of the acetylcholine-induced contractions on the isolated ileal segments and finally produced sustained spasmodic contractions. This spasmodic action was abolished by 1 microM atropine. The venom produced haemolysis of red blood cells in a concentration-dependent and duration-of-exposure manner, with 100% of haemolysis produced after 24h following exposure to 40 microg/ml of venom. While cultured fibroblasts cells were more sensitive and disintegrated after 15 min of exposure to 1 microg/ml of the venom. Histological findings showed evidences of excessive inflammatory responses accompanied with signs of necrosis in the skin at the site of injection as well as structural damage in the nephrones. There was a significant rise in the serum enzymes. In addition, the number of the RBCs were reduced. The urine showed positive readings for proteinuria, blood and intact RBCs. The overall results suggest that the venom from H. lepturus primarily is a cytotoxic agent and has haemolytic, nephrotoxic and to some extent hepatotoxic activity.