Effects Of Selective Antagonism Of Histamine Receptors On Acute Lethality Induced By Tityus serrulatus Scorpion Venom In Mice. 

¹Souza,C.MV.; ¹Pais,K.S; ¹Barbeito;K.D.

1 Assessoria Científica, Instituto Vital Brazil, Niterói, RJ, Brasil

Pulmonary edema is belived the most important cause of human death induced by Tityusserrulatus scorpion stings. In order to evaluate the role of H1 and H2 receptors on acute lethality in a severe experimental scorpionism model, five groups of six male mice (20±2g) were injected with a range (0.33-1.75mg/kg ip) of Tityusserrulatus scorpion crude venom (TSV) and the Lethal Dose 50% (LD50) determined (0.97mg/kg). Another animals were pre-treated (90’) with H1 blocker Prometazine (PRZ) (0.5mg/kg ip), and a third group of mice received Cimetidine (CMT) (10mg/kg ip) as H2 receptor antagonist at the same conditions before venom treatment. Pre-treatment with PRZ moves the TSV lethal curve for left (LD50=0.69 mg/kg ip) and increased the number of dead animals treated with the highest dose of TSV (p<0.05). The latency of venom lethalithy was reduced (p<0.05) in all doses in the presence of PRZ (24.3±5.4min,n=49) when compared to control (48.4± 3.0 min,n=36). Selective antagonism of H2 receptors with CMT moves the venom lethal curve for right (LD50=1.34 mg/kg ip) and reduced (p<0.05) the lethal effects of TSV at 0.5 mg/kg ip and 0.75 mg/kg ip.Our results indicates a deep antagonic role of diferent histaminergic receptors on the development of severe experimental scorpionism and may sugests Cimetidine as agent of choice in Tityusserrulatus scorpion envenoming treatment  and prevention of adverse effects of  antivenom therapy.

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Correspondence to: artropodos@ivb.rj.gov.br