Effect of Indian red scorpion (Mesobuthus tamulus concanesis, Pocock) venom on thyroxine and triiodothyronine in experimental acute myocarditis and its reversal by species specific antivenom.

Acute myocarditis was induced in dogs and rabbits by injection of scorpion (M. tamulus concanesis, earlier called Buthus tamulus) venom by s.c., i.m. or i.v. routes. A decrease in thyroxine (T4) levels was observed following i.v. injection of venom in dogs. In rabbits the venom (i.m.) did not elicit any change in T4 levels. Envenomation (s.c.) resulted in a reduction in triiodothyronine (T3) levels in dogs. Venom injection (s.c.) along with i.v. administration of the species specific antivenom (AScVS) did not cause any change in T3 and T4 levels in general. However an increase in T3 levels following AScVS was observed in envenomated dogs. The results suggest that scorpion envenomation caused an autonomic storm releasing massive amounts of catecholamines, angiotensin II, suppressed insulin secretion and reduced circulating T4 and T3 levels. Decrease in thyroid hormones results in fall in body temperature. Changes in the body temperature may increase the sensitivity of the scorpion venom and influence the course of toxicity.