Constitutive deletion of translin (Tsn) enhances locomotor response to amphetamine: role of developmental effects

The translin/trax microRNA-degrading enzyme mediates activity-induced changes in translation that underlie several long-lasting forms of cellular plasticity. As translin and trax are expressed in dopaminergic and striatal neurons, we investigated whether deletion of Tsn blocks amphetamine sensitization, a long-lasting, translation-dependent form of behavioral plasticity.Although we had hypothesized that constitutive Tsn deletion would impair amphetamine sensitization, we found, instead, that it enhances the hyperlocomotion produced by the initial dose of amphetamine. Since these mice display elevated adiposity, which alters pharmacokinetics of many drugs, we measured brain levels of amphetamine in Tsn knockout mice and found that these are elevated. As conditional Tsn deletion in adulthood does not impact adiposity, we monitored the locomotor response to amphetamine following this manipulation. Acute and sensitized responses to amphetamine are not altered in these mice, indicating that the enhanced amphetamine response displayed by constitutive Tsn knockout mice is due to Tsn absence during development.