Spontaneous T. gondii neuronal encystment induces structural neuritic network impairment associated with changes of tyrosine hydroxilase expression

•T. gondii Brazilian strain #11 infects and spontaneously encysts in neurons.•Encystment causes enlargement of neuritis and neuritis network impairment.•Infection induces a relative increase in the area of the network expressing TH compared to the intact cultures.•One product of TH enzymatic action, the dopamine, is unchanged along the kinetics.•Our system allows elucidating cystogenesis associated neurotransmitter changes. Two billion people are chronically infected with Toxoplasma gondii worldwide with unknown consequences. Important neurological diseases have been associated to the brain infection, making essential to understand the neurophysiological changes associated with the neuronal encystment. T. gondii may subvert neuronal functions modifying neurotransmitter concentration in chronically infected mice but the molecular mechanisms involved are still unclear. Parasites were observed inside neuronal cells in cultures from 24−192 hs. The rate of infection increased with time. Neurite density decreased affecting network functionality. Neuronal survival was affected and we detected the presence of cysts inside neuronal bodies and dilated portions of neurites in association with a relative increase of TH-positive neuritic area without noticeable changes in DA immunofluorescence pattern. These results advance our knowledge of the interaction between T. gondii and the neuronal network of the host.