Experimental change in personality: Overexpression of GDNF in the rat striatum converts the low exploratory phenotype into highly explorative

Major vulnerability factors for psychiatric disorders such as depression, that often prevent complete remission and lead to relapses, are temperamental. In a rat model of clustered persistent high anxiety/low motivation, we have found that overexpression of glial-cell-line-derived neurotrophic factor (GDNF) by intra-striatally administered adeno-associated virus vector strikingly converts the passive coping style of low exploratory rats into an active one, similar to high exploratory rats. This conversion of behavioural strategy developed gradually over repeated testing, and was associated with increased catecholamine metabolism in several brain regions and changes in the regulation of serotonin neurotransmission. An increase in in vivo dopamine transporter availability in the striatum was necessary for the phenotype conversion. Associated changes in striatal gene expression included key players in monoamine storage and epitranscriptomic regulation. The increase in GDNF signalling also caused alterations in levels and regional covariation of oxidative metabolism, indicative of persistent reorganization of neural activity throughout the brain. Thus, neurotrophic factors, GDNF in particular, may play a pivotal role in the development, persistence and alteration of personality traits, and therefore constitute a potential target for treatment of chronic, relapsing psychiatric disorders.