Chronic murine toxoplasmosis is defined by subtle changes in neuronal connectivity

Area of Science:

• Neuroscience
• Immunology
• Infectious Diseases

Background:

• Chronic Toxoplasma gondii infection is linked to behavioral changes in rodents and neuropsychiatric conditions in humans.
• The underlying mechanisms connecting T. gondii infection to neurological alterations remain unclear.

Purpose of the Study:

• To investigate the impact of chronic T. gondii infection on synaptic plasticity and brain neuronal circuitry in a murine model.
• To explore the relationship between T. gondii-induced brain lesions and neurobiological changes.

Main Methods:

• Magnetic resonance imaging (MRI) and diffusion-tensor MRI were used to analyze brain lesions and neuronal connectivity.
• Histopathological examination assessed glial activation, immune cell infiltration, and neuronal morphology.
• Levels of synaptic proteins (PSD95, synaptophysin) were measured to evaluate synapse efficacy.

Main Results:

• T. gondii infection caused widespread brain lesions, particularly in the somatosensory cortex (SSC).
• Infected mice exhibited reduced dendritic arbor and spine density in neurons within the SSC and hippocampus.
• Deficits in synaptic proteins indicated impaired synaptic neurotransmission, alongside altered brain connectivity.

Conclusions:

• Persistent T. gondii infection leads to synaptic deficits and altered neuronal morphology in the murine brain.
• These neurobiological changes provide a potential explanation for the behavioral and neuropsychiatric alterations associated with toxoplasmosis.