Differentialin vitroeffects of insulin onTaenia crassicepsandTaenia soliumcysticerci

Abstract

AbstractHormones play a significant role in murine cysticercosis (Taenia crassiceps), and increase the frequency of porcine cysticercosis caused byTaenia solium. In the present study, we report thein vitroeffect of insulin on the larval stages ofT. crassiceps(ORF strain) andT. solium.In vitroexposure ofT. crassicepscysticerci to insulin was found to stimulate this parasite's reproduction twofold with respect to control values, while the same treatment had no effect onT. soliumcysticerci. Moreover, normal female mice (BALB/cAnN) infected withT. crassicepscysticerci previously exposed to insulin presented larger parasite loads than mice inoculated with vehicle-treated cysticerci. To determine the possible molecular mechanisms by which insulin affectsT. crassiceps, the insulin receptor was amplified by means of reverse transcriptase-polymerase chain reaction (RT-PCR). Interestingly, bothT. crassicepsandT. soliumexpressed the insulin receptor, although insulin had effects only onT. crassiceps. These results demonstrate that insulin has a dichotomistic effect; it acts directly only onT. crassicepscysticerci reproduction, possibly through its binding to a specific insulin receptor synthesized by the parasite. Thus, insulin may be recognized byT. crassicepscysticercus cells as a mitogenic factor, and contribute to parasite proliferation inside the host, as well as to the female mouse susceptibility toT.crassiceps. This phenomenon has not been reported for cysticercosis caused byT. solium, which could, in part, be related to the poor effect of insulin upon the human parasite.