Acute toxicity of βγ-CAT, a naturally existing non-lens βγ-crystallin and trefoil factor complex from frog Bombina maxima skin secretions

In vertebrates, non-lens beta gamma-crystallins are widely expressed in various tissues, but their functions are unknown. The molecular mechanisms of trefoil factors, initiators of mucosal healing and being greatly involved in tumorigenesis, have remained elusive. beta gamma-CAT is the first example of a naturally existing multifunctional protein complex of a non-lens beta gamma-crystallin and a trefoil factor from frog Bombina maxima skin secretions. Here we report the investigation of its in vivo toxic effects on mice and rabbits. The LD(50) values of beta gamma-CAT on mice were determined to be 0.4 mg/kg and 20 mu g/kg under intraperitoneal (i.p.) and intravenous (i.v.) injection, respectively. The mice subcutaneously injected with beta gamma-CAT (6 mu g/g body weight) showed strong hyperaemia of subcutaneous capillary vessel, but no hemorrhagic spots were observed. Intravenous injection of beta gamma-CAT in rabbits (8-22 mu g/kg body weight) caused a rapidly hypotensive effect and followed with cardiovascular collapse. Injection with beta gamma-CAT (22 mu g/kg, i.v.) significantly decreased hematocrit (P < 0.05) and mean corpuscular volume (P < 0.05) of the rabbits in 5 min. At the same time, the counts of platelets and white blood cells were significantly decreased (P < 0.05), while the blood levels of glucose, lactate dehydrogenase and serum glutamic-oxaloacetic transaminase were significantly increased (P < 0.05). Furthermore, serials of tissues edema and damages were also observed. These results indicate that beta gamma-CAT rapidly caused several in vivo toxic effects on mammals and its lethal toxic potency was mainly contributed by hypotension and cardiovascular collapse, providing new clues for the understanding of the patho-physiological roles of non-lens beta gamma-crystallins and trefoil factors. (C) 2008 Elsevier Ltd. All rights reserved.