Immunochemical detection of Lonomia obliqua caterpillar venom in rats

Severe cases of human envenoming by caterpillars of the saturniid moth Lonomia obliqua in Brazil can result in renal damage, leading to renal failure, and intracerebral hemorrhaging. In this work, we used immunohistochemical staining with rabbit antiserum raised against L. obliqua venom to examine venom distribution in selected tissues of the brain (cerebellum and hippocampus), kidneys, and liver of male Wistar rats injected with a single dose of venom (200 microg/kg, i.v.) and sacrificed 6, 18, 24, and 72 hours later. The immunolabeling of GFAP was also examined to assess the venom effects on perivascular astrocytic end-feet in the microvasculature of the hippocampus and cerebellum. Venom was detected in the kidneys (6 and 18 hours) and in the liver (6 hours) but not in the brain at any of the time intervals examined. In contrast, immunolabeling for GFAP revealed astrogliosis in the cerebellum and enhanced expression of this protein in the glial processes of the cerebellum and hippocampus, with a maximum response from 24 hours onwards. The high immunoreactivity seen in the kidneys agreed with the renal damage and dysfunction reported for some patients. The lack of venom detection in the brain, despite the altered expression of GFAP in astrocytes, suggested either that the venom does not enter this organ or that its entrance is transient and fast. Alternatively, the circulating venom may induce the release of mediators that could serve as second messengers to provoke the late astrocytic reactivity and astrogliosis. It is possible that both of these mechanisms may contribute to the effects observed.